[PATCH v7 00/10] Small-sized THP for anonymous memory

[PATCH v7 00/10] Small-sized THP for anonymous memory

[Ryan Roberts]

Hi All,

This is v7 of a series to implement small-sized THP for anonymous memory
(previously called "large anonymous folios"). The objective of this is to
improve performance by allocating larger chunks of memory during anonymous page
faults:

1) Since SW (the kernel) is dealing with larger chunks of memory than base
   pages, there are efficiency savings to be had; fewer page faults, batched PTE
   and RMAP manipulation, reduced lru list, etc. In short, we reduce kernel
   overhead. This should benefit all architectures.
2) Since we are now mapping physically contiguous chunks of memory, we can take
   advantage of HW TLB compression techniques. A reduction in TLB pressure
   speeds up kernel and user space. arm64 systems have 2 mechanisms to coalesce
   TLB entries; "the contiguous bit" (architectural) and HPA (uarch).

The major change in this revision is the migration to a new sysfs interface as
recommended by David Hildenbrand - thanks to David for the suggestion! This
interface is inspired by the existing per-hugepage-size sysfs interface used by
hugetlb, provides full backwards compatibility with the existing PMD-size THP
interface, and provides a base for future extensibility. See [7] for detailed
discussion of the interface.

By default, the existing behaviour (and performance) is maintained. The user
must explicitly enable small-sized THP to see the performance benefit.

The series has also become heavy with mm selftest changes: These all relate to
enlightenment of cow and khugepaged tests to explicitly test with small-sized
THP.

This series is based on mm-unstable (60df8b4235f5).


Prerequisites
=============

Some work items identified as being prerequisites are listed on page 3 at [8].
The summary is:

| item                          | status                  |
|:------------------------------|:------------------------|
| mlock                         | In mainline (v6.7)      |
| madvise                       | In mainline (v6.6)      |
| compaction                    | v1 posted [9]           |
| numa balancing                | Investigated: see below |
| user-triggered page migration | In mainline (v6.7)      |
| khugepaged collapse           | In mainline (NOP)       |

On NUMA balancing, which currently ignores any PTE-mapped THPs it encounters,
John Hubbard has investigated this and concluded that it is A) not clear at the
moment what a better policy might be for PTE-mapped THP and B) questions whether
this should really be considered a prerequisite given no regression is caused
for the default "small-sized THP disabled" case, and there is no correctness
issue when it is enabled - its just a potential for non-optimal performance.
(John please do elaborate if I haven't captured this correctly!)

If there are no disagreements about removing numa balancing from the list, then
that just leaves compaction which is in review on list at the moment.

I really would like to get this series (and its remaining comapction
prerequisite) in for v6.8. I accept that it may be a bit optimistic at this
point, but lets see where we get to with review?


Testing
=======

The series includes patches for mm selftests to enlighten the cow and khugepaged
tests to explicitly test with small-order THP, in the same way that PMD-order
THP is tested. The new tests all pass, and no regressions are observed in the mm
selftest suite. I've also run my usual kernel compilation and java script
benchmarks without any issues.

Refer to my performance numbers posted with v6 [6]. (These are for small-sized
THP only - they do not include the arm64 contpte follow-on series).

John Hubbard at Nvidia has indicated dramatic 10x performance improvements for
some workloads at [10]. (Observed using v6 of this series as well as the arm64
contpte series).

Kefeng Wang at Huawei has also indicated he sees improvements at [11] although
there are some latency regressions also.


Changes since v6 [6]
====================

  - Refactored vmf_pte_range_changed() to remove uffd special-case (suggested by
    JohnH)
  - Dropped accounting patch (#3 in v6) (suggested by DavidH)
      - Continue to account *PMD-sized* THP only for now
      - Can add more counters in future if needed
      - Page cache large folios haven't needed any new counters yet
  - Pivot to sysfs ABI proposed by DavidH
      - per-size directories in a similar shape to that used by hugetlb
  - Dropped "recommend" keyword patch (#6 in v6) (suggested by DavidH, Yu Zhou)
      - For now, users need to understand implicitly which sizes are beneficial
        to their HW/SW
  - Dropped arch_wants_pte_order() patch (#7 in v6)
      - No longer needed due to dropping patch "recommend" keyword patch
  - Enlightened khugepaged mm selftest to explicitly test with small-size THP
  - Scrubbed commit logs to use "small-sized THP" consistently (suggested by
    DavidH)


Changes since v5 [5]
====================

  - Added accounting for PTE-mapped THPs (patch 3)
  - Added runtime control mechanism via sysfs as extension to THP (patch 4)
  - Minor refactoring of alloc_anon_folio() to integrate with runtime controls
  - Stripped out hardcoded policy for allocation order; its now all user space
    controlled (although user space can request "recommend" which will configure
    the HW-preferred order)


Changes since v4 [4]
====================

  - Removed "arm64: mm: Override arch_wants_pte_order()" patch; arm64
    now uses the default order-3 size. I have moved this patch over to
    the contpte series.
  - Added "mm: Allow deferred splitting of arbitrary large anon folios" back
    into series. I originally removed this at v2 to add to a separate series,
    but that series has transformed significantly and it no longer fits, so
    bringing it back here.
  - Reintroduced dependency on set_ptes(); Originally dropped this at v2, but
    set_ptes() is in mm-unstable now.
  - Updated policy for when to allocate LAF; only fallback to order-0 if
    MADV_NOHUGEPAGE is present or if THP disabled via prctl; no longer rely on
    sysfs's never/madvise/always knob.
  - Fallback to order-0 whenever uffd is armed for the vma, not just when
    uffd-wp is set on the pte.
  - alloc_anon_folio() now returns `struct folio *`, where errors are encoded
    with ERR_PTR().

  The last 3 changes were proposed by Yu Zhao - thanks!


Changes since v3 [3]
====================

  - Renamed feature from FLEXIBLE_THP to LARGE_ANON_FOLIO.
  - Removed `flexthp_unhinted_max` boot parameter. Discussion concluded that a
    sysctl is preferable but we will wait until real workload needs it.
  - Fixed uninitialized `addr` on read fault path in do_anonymous_page().
  - Added mm selftests for large anon folios in cow test suite.


Changes since v2 [2]
====================

  - Dropped commit "Allow deferred splitting of arbitrary large anon folios"
      - Huang, Ying suggested the "batch zap" work (which I dropped from this
        series after v1) is a prerequisite for merging FLXEIBLE_THP, so I've
        moved the deferred split patch to a separate series along with the batch
        zap changes. I plan to submit this series early next week.
  - Changed folio order fallback policy
      - We no longer iterate from preferred to 0 looking for acceptable policy
      - Instead we iterate through preferred, PAGE_ALLOC_COSTLY_ORDER and 0 only
  - Removed vma parameter from arch_wants_pte_order()
  - Added command line parameter `flexthp_unhinted_max`
      - clamps preferred order when vma hasn't explicitly opted-in to THP
  - Never allocate large folio for MADV_NOHUGEPAGE vma (or when THP is disabled
    for process or system).
  - Simplified implementation and integration with do_anonymous_page()
  - Removed dependency on set_ptes()


Changes since v1 [1]
====================

  - removed changes to arch-dependent vma_alloc_zeroed_movable_folio()
  - replaced with arch-independent alloc_anon_folio()
      - follows THP allocation approach
  - no longer retry with intermediate orders if allocation fails
      - fallback directly to order-0
  - remove folio_add_new_anon_rmap_range() patch
      - instead add its new functionality to folio_add_new_anon_rmap()
  - remove batch-zap pte mappings optimization patch
      - remove enabler folio_remove_rmap_range() patch too
      - These offer real perf improvement so will submit separately
  - simplify Kconfig
      - single FLEXIBLE_THP option, which is independent of arch
      - depends on TRANSPARENT_HUGEPAGE
      - when enabled default to max anon folio size of 64K unless arch
        explicitly overrides
  - simplify changes to do_anonymous_page():
      - no more retry loop


[1] https://lore.kernel.org/linux-mm/20230626171430.3167004-1-ryan.roberts@arm.com/
[2] https://lore.kernel.org/linux-mm/20230703135330.1865927-1-ryan.roberts@arm.com/
[3] https://lore.kernel.org/linux-mm/20230714160407.4142030-1-ryan.roberts@arm.com/
[4] https://lore.kernel.org/linux-mm/20230726095146.2826796-1-ryan.roberts@arm.com/
[5] https://lore.kernel.org/linux-mm/20230810142942.3169679-1-ryan.roberts@arm.com/
[6] https://lore.kernel.org/linux-mm/20230929114421.3761121-1-ryan.roberts@arm.com/
[7] https://lore.kernel.org/linux-mm/6d89fdc9-ef55-d44e-bf12-fafff318aef8@redhat.com/
[8] https://drive.google.com/file/d/1GnfYFpr7_c1kA41liRUW5YtCb8Cj18Ud/view?usp=sharing&resourcekey=0-U1Mj3-RhLD1JV6EThpyPyA
[9] https://lore.kernel.org/linux-mm/20231113170157.280181-1-zi.yan@sent.com/
[10] https://lore.kernel.org/linux-mm/c507308d-bdd4-5f9e-d4ff-e96e4520be85@nvidia.com/
[11] https://lore.kernel.org/linux-mm/479b3e2b-456d-46c1-9677-38f6c95a0be8@huawei.com/


Thanks,
Ryan

Ryan Roberts (10):
  mm: Allow deferred splitting of arbitrary anon large folios
  mm: Non-pmd-mappable, large folios for folio_add_new_anon_rmap()
  mm: thp: Introduce per-size thp sysfs interface
  mm: thp: Support allocation of anonymous small-sized THP
  selftests/mm/kugepaged: Restore thp settings at exit
  selftests/mm: Factor out thp settings management
  selftests/mm: Support small-sized THP interface in thp_settings
  selftests/mm/khugepaged: Enlighten for small-sized THP
  selftests/mm/cow: Generalize do_run_with_thp() helper
  selftests/mm/cow: Add tests for anonymous small-sized THP

 Documentation/admin-guide/mm/transhuge.rst |  74 +++-
 Documentation/filesystems/proc.rst         |   6 +-
 fs/proc/task_mmu.c                         |   3 +-
 include/linux/huge_mm.h                    | 102 +++--
 mm/huge_memory.c                           | 263 +++++++++++--
 mm/khugepaged.c                            |  16 +-
 mm/memory.c                                | 112 +++++-
 mm/page_vma_mapped.c                       |   3 +-
 mm/rmap.c                                  |  32 +-
 tools/testing/selftests/mm/Makefile        |   4 +-
 tools/testing/selftests/mm/cow.c           | 215 +++++++----
 tools/testing/selftests/mm/khugepaged.c    | 410 ++++-----------------
 tools/testing/selftests/mm/run_vmtests.sh  |   2 +
 tools/testing/selftests/mm/thp_settings.c  | 349 ++++++++++++++++++
 tools/testing/selftests/mm/thp_settings.h  |  80 ++++
 15 files changed, 1160 insertions(+), 511 deletions(-)
 create mode 100644 tools/testing/selftests/mm/thp_settings.c
 create mode 100644 tools/testing/selftests/mm/thp_settings.h

--
2.25.1

[PATCH v7 01/10] mm: Allow deferred splitting of arbitrary anon large folios

[Ryan Roberts]

In preparation for the introduction of anonymous small-sized THP, we
would like to be able to split them when they have unmapped subpages, in
order to free those unused pages under memory pressure. So remove the
artificial requirement that the large folio needed to be at least
PMD-sized.

Reviewed-by: Yu Zhao <yuzhao@google.com>
Reviewed-by: Yin Fengwei <fengwei.yin@intel.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
---
 mm/rmap.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/rmap.c b/mm/rmap.c
index 7a27a2b41802..49e4d86a4f70 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1488,11 +1488,11 @@ void page_remove_rmap(struct page *page, struct vm_area_struct *vma,
 		__lruvec_stat_mod_folio(folio, idx, -nr);
 
 		/*
-		 * Queue anon THP for deferred split if at least one
+		 * Queue anon large folio for deferred split if at least one
 		 * page of the folio is unmapped and at least one page
 		 * is still mapped.
 		 */
-		if (folio_test_pmd_mappable(folio) && folio_test_anon(folio))
+		if (folio_test_large(folio) && folio_test_anon(folio))
 			if (!compound || nr < nr_pmdmapped)
 				deferred_split_folio(folio);
 	}
-- 
2.25.1

[PATCH v7 02/10] mm: Non-pmd-mappable, large folios for folio_add_new_anon_rmap()

[Ryan Roberts]

In preparation for supporting anonymous small-sized THP, improve
folio_add_new_anon_rmap() to allow a non-pmd-mappable, large folio to be
passed to it. In this case, all contained pages are accounted using the
order-0 folio (or base page) scheme.

Reviewed-by: Yu Zhao <yuzhao@google.com>
Reviewed-by: Yin Fengwei <fengwei.yin@intel.com>
Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
---
 mm/rmap.c | 28 ++++++++++++++++++++--------
 1 file changed, 20 insertions(+), 8 deletions(-)

diff --git a/mm/rmap.c b/mm/rmap.c
index 49e4d86a4f70..b086dc957b0c 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1305,32 +1305,44 @@ void page_add_anon_rmap(struct page *page, struct vm_area_struct *vma,
  * This means the inc-and-test can be bypassed.
  * The folio does not have to be locked.
  *
- * If the folio is large, it is accounted as a THP.  As the folio
+ * If the folio is pmd-mappable, it is accounted as a THP.  As the folio
  * is new, it's assumed to be mapped exclusively by a single process.
  */
 void folio_add_new_anon_rmap(struct folio *folio, struct vm_area_struct *vma,
 		unsigned long address)
 {
-	int nr;
+	int nr = folio_nr_pages(folio);
 
-	VM_BUG_ON_VMA(address < vma->vm_start || address >= vma->vm_end, vma);
+	VM_BUG_ON_VMA(address < vma->vm_start ||
+			address + (nr << PAGE_SHIFT) > vma->vm_end, vma);
 	__folio_set_swapbacked(folio);
+	__folio_set_anon(folio, vma, address, true);
 
-	if (likely(!folio_test_pmd_mappable(folio))) {
+	if (likely(!folio_test_large(folio))) {
 		/* increment count (starts at -1) */
 		atomic_set(&folio->_mapcount, 0);
-		nr = 1;
+		SetPageAnonExclusive(&folio->page);
+	} else if (!folio_test_pmd_mappable(folio)) {
+		int i;
+
+		for (i = 0; i < nr; i++) {
+			struct page *page = folio_page(folio, i);
+
+			/* increment count (starts at -1) */
+			atomic_set(&page->_mapcount, 0);
+			SetPageAnonExclusive(page);
+		}
+
+		atomic_set(&folio->_nr_pages_mapped, nr);
 	} else {
 		/* increment count (starts at -1) */
 		atomic_set(&folio->_entire_mapcount, 0);
 		atomic_set(&folio->_nr_pages_mapped, COMPOUND_MAPPED);
-		nr = folio_nr_pages(folio);
+		SetPageAnonExclusive(&folio->page);
 		__lruvec_stat_mod_folio(folio, NR_ANON_THPS, nr);
 	}
 
 	__lruvec_stat_mod_folio(folio, NR_ANON_MAPPED, nr);
-	__folio_set_anon(folio, vma, address, true);
-	SetPageAnonExclusive(&folio->page);
 }
 
 /**
-- 
2.25.1

[PATCH v7 03/10] mm: thp: Introduce per-size thp sysfs interface

[Ryan Roberts]

In preparation for adding support for anonymous small-sized THP,
introduce new sysfs structure that will be used to control the new
behaviours. A new directory is added under transparent_hugepage for each
supported THP size, and contains an `enabled` file, which can be set to
"global" (to inherrit the global setting), "always", "madvise" or
"never". For now, the kernel still only supports PMD-sized anonymous
THP, so only 1 directory is populated.

The first half of the change converts transhuge_vma_suitable() and
hugepage_vma_check() so that they take a bitfield of orders for which
the user wants to determine support, and the functions filter out all
the orders that can't be supported, given the current sysfs
configuration and the VMA dimensions. If there is only 1 order set in
the input then the output can continue to be treated like a boolean;
this is the case for most call sites.

The second half of the change implements the new sysfs interface. It has
been done so that each supported THP size has a `struct thpsize`, which
describes the relevant metadata and is itself a kobject. This is pretty
minimal for now, but should make it easy to add new per-thpsize files to
the interface if needed in future (e.g. per-size defrag). Rather than
keep the `enabled` state directly in the struct thpsize, I've elected to
directly encode it into huge_anon_orders_[always|madvise|global]
bitfields since this reduces the amount of work required in
transhuge_vma_suitable() which is called for every page fault.

The remainder is copied from Documentation/admin-guide/mm/transhuge.rst,
as modified by this commit. See that file for further details.

Transparent Hugepage Support for anonymous memory can be entirely
disabled (mostly for debugging purposes) or only enabled inside
MADV_HUGEPAGE regions (to avoid the risk of consuming more memory
resources) or enabled system wide. This can be achieved
per-supported-THP-size with one of::

	echo always >/sys/kernel/mm/transparent_hugepage/hugepages-<size>kB/enabled
	echo madvise >/sys/kernel/mm/transparent_hugepage/hugepages-<size>kB/enabled
	echo never >/sys/kernel/mm/transparent_hugepage/hugepages-<size>kB/enabled

where <size> is the hugepage size being addressed, the available sizes
for which vary by system. Alternatively it is possible to specify that
a given hugepage size will inherrit the global enabled setting::

	echo global >/sys/kernel/mm/transparent_hugepage/hugepages-<size>kB/enabled

The global (legacy) enabled setting can be set as follows::

	echo always >/sys/kernel/mm/transparent_hugepage/enabled
	echo madvise >/sys/kernel/mm/transparent_hugepage/enabled
	echo never >/sys/kernel/mm/transparent_hugepage/enabled

By default, PMD-sized hugepages have enabled="global" and all other
hugepage sizes have enabled="never". If enabling multiple hugepage
sizes, the kernel will select the most appropriate enabled size for a
given allocation.

Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
---
 Documentation/admin-guide/mm/transhuge.rst |  74 ++++--
 Documentation/filesystems/proc.rst         |   6 +-
 fs/proc/task_mmu.c                         |   3 +-
 include/linux/huge_mm.h                    | 100 +++++---
 mm/huge_memory.c                           | 263 +++++++++++++++++++--
 mm/khugepaged.c                            |  16 +-
 mm/memory.c                                |   6 +-
 mm/page_vma_mapped.c                       |   3 +-
 8 files changed, 387 insertions(+), 84 deletions(-)

diff --git a/Documentation/admin-guide/mm/transhuge.rst b/Documentation/admin-guide/mm/transhuge.rst
index b0cc8243e093..52565e0bd074 100644
--- a/Documentation/admin-guide/mm/transhuge.rst
+++ b/Documentation/admin-guide/mm/transhuge.rst
@@ -45,10 +45,23 @@ components:
    the two is using hugepages just because of the fact the TLB miss is
    going to run faster.
 
+As well as PMD-sized THP described above, it is also possible to
+configure the system to allocate "small-sized THP" to back anonymous
+memory (for example 16K, 32K, 64K, etc). These THPs continue to be
+PTE-mapped, but in many cases can still provide similar benefits to
+those outlined above: Page faults are significantly reduced (by a
+factor of e.g. 4, 8, 16, etc), but latency spikes are much less
+prominent because the size of each page isn't as huge as the PMD-sized
+variant and there is less memory to clear in each page fault. Some
+architectures also employ TLB compression mechanisms to squeeze more
+entries in when a set of PTEs are virtually and physically contiguous
+and approporiately aligned. In this case, TLB misses will occur less
+often.
+
 THP can be enabled system wide or restricted to certain tasks or even
 memory ranges inside task's address space. Unless THP is completely
 disabled, there is ``khugepaged`` daemon that scans memory and
-collapses sequences of basic pages into huge pages.
+collapses sequences of basic pages into PMD-sized huge pages.
 
 The THP behaviour is controlled via :ref:`sysfs <thp_sysfs>`
 interface and using madvise(2) and prctl(2) system calls.
@@ -95,12 +108,29 @@ Global THP controls
 Transparent Hugepage Support for anonymous memory can be entirely disabled
 (mostly for debugging purposes) or only enabled inside MADV_HUGEPAGE
 regions (to avoid the risk of consuming more memory resources) or enabled
-system wide. This can be achieved with one of::
+system wide. This can be achieved per-supported-THP-size with one of::
+
+	echo always >/sys/kernel/mm/transparent_hugepage/hugepages-<size>kB/enabled
+	echo madvise >/sys/kernel/mm/transparent_hugepage/hugepages-<size>kB/enabled
+	echo never >/sys/kernel/mm/transparent_hugepage/hugepages-<size>kB/enabled
+
+where <size> is the hugepage size being addressed, the available sizes
+for which vary by system. Alternatively it is possible to specify that
+a given hugepage size will inherrit the global enabled setting::
+
+	echo global >/sys/kernel/mm/transparent_hugepage/hugepages-<size>kB/enabled
+
+The global (legacy) enabled setting can be set as follows::
 
 	echo always >/sys/kernel/mm/transparent_hugepage/enabled
 	echo madvise >/sys/kernel/mm/transparent_hugepage/enabled
 	echo never >/sys/kernel/mm/transparent_hugepage/enabled
 
+By default, PMD-sized hugepages have enabled="global" and all other
+hugepage sizes have enabled="never". If enabling multiple hugepage
+sizes, the kernel will select the most appropriate enabled size for a
+given allocation.
+
 It's also possible to limit defrag efforts in the VM to generate
 anonymous hugepages in case they're not immediately free to madvise
 regions or to never try to defrag memory and simply fallback to regular
@@ -146,25 +176,34 @@ madvise
 never
 	should be self-explanatory.
 
-By default kernel tries to use huge zero page on read page fault to
-anonymous mapping. It's possible to disable huge zero page by writing 0
-or enable it back by writing 1::
+By default kernel tries to use huge, PMD-mappable zero page on read
+page fault to anonymous mapping. It's possible to disable huge zero
+page by writing 0 or enable it back by writing 1::
 
 	echo 0 >/sys/kernel/mm/transparent_hugepage/use_zero_page
 	echo 1 >/sys/kernel/mm/transparent_hugepage/use_zero_page
 
-Some userspace (such as a test program, or an optimized memory allocation
-library) may want to know the size (in bytes) of a transparent hugepage::
+Some userspace (such as a test program, or an optimized memory
+allocation library) may want to know the size (in bytes) of a
+PMD-mappable transparent hugepage::
 
 	cat /sys/kernel/mm/transparent_hugepage/hpage_pmd_size
 
-khugepaged will be automatically started when
-transparent_hugepage/enabled is set to "always" or "madvise, and it'll
-be automatically shutdown if it's set to "never".
+khugepaged will be automatically started when one or more hugepage
+sizes are enabled (either by directly setting "always" or "madvise",
+or by setting "global" while the global enabled is set to "always" or
+"madvise"), and it'll be automatically shutdown when the last hugepage
+size is disabled (either by directly setting "never", or by setting
+"global" while the global enabled is set to "never").
 
 Khugepaged controls
 -------------------
 
+.. note::
+   khugepaged currently only searches for opportunities to collapse to
+   PMD-sized THP and no attempt is made to collapse to small-sized
+   THP.
+
 khugepaged runs usually at low frequency so while one may not want to
 invoke defrag algorithms synchronously during the page faults, it
 should be worth invoking defrag at least in khugepaged. However it's
@@ -282,10 +321,11 @@ force
 Need of application restart
 ===========================
 
-The transparent_hugepage/enabled values and tmpfs mount option only affect
-future behavior. So to make them effective you need to restart any
-application that could have been using hugepages. This also applies to the
-regions registered in khugepaged.
+The transparent_hugepage/enabled and
+transparent_hugepage/hugepages-<size>kB/enabled values and tmpfs mount
+option only affect future behavior. So to make them effective you need
+to restart any application that could have been using hugepages. This
+also applies to the regions registered in khugepaged.
 
 Monitoring usage
 ================
@@ -308,6 +348,10 @@ frequently will incur overhead.
 There are a number of counters in ``/proc/vmstat`` that may be used to
 monitor how successfully the system is providing huge pages for use.
 
+.. note::
+   Currently the below counters only record events relating to
+   PMD-sized THP. Events relating to small-sized THP are not included.
+
 thp_fault_alloc
 	is incremented every time a huge page is successfully
 	allocated to handle a page fault.
@@ -413,7 +457,7 @@ for huge pages.
 Optimizing the applications
 ===========================
 
-To be guaranteed that the kernel will map a 2M page immediately in any
+To be guaranteed that the kernel will map a THP immediately in any
 memory region, the mmap region has to be hugepage naturally
 aligned. posix_memalign() can provide that guarantee.
 
diff --git a/Documentation/filesystems/proc.rst b/Documentation/filesystems/proc.rst
index 49ef12df631b..f8e8dd1fd148 100644
--- a/Documentation/filesystems/proc.rst
+++ b/Documentation/filesystems/proc.rst
@@ -528,9 +528,9 @@ replaced by copy-on-write) part of the underlying shmem object out on swap.
 does not take into account swapped out page of underlying shmem objects.
 "Locked" indicates whether the mapping is locked in memory or not.
 
-"THPeligible" indicates whether the mapping is eligible for allocating THP
-pages as well as the THP is PMD mappable or not - 1 if true, 0 otherwise.
-It just shows the current status.
+"THPeligible" indicates whether the mapping is eligible for allocating
+naturally aligned THP pages of any currently enabled size. 1 if true, 0
+otherwise. It just shows the current status.
 
 "VmFlags" field deserves a separate description. This member represents the
 kernel flags associated with the particular virtual memory area in two letter
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 51e0ec658457..2e25362ca9fa 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -865,7 +865,8 @@ static int show_smap(struct seq_file *m, void *v)
 	__show_smap(m, &mss, false);
 
 	seq_printf(m, "THPeligible:    %8u\n",
-		   hugepage_vma_check(vma, vma->vm_flags, true, false, true));
+		   !!hugepage_vma_check(vma, vma->vm_flags, true, false, true,
+					THP_ORDERS_ALL));
 
 	if (arch_pkeys_enabled())
 		seq_printf(m, "ProtectionKey:  %8u\n", vma_pkey(vma));
diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index fa0350b0812a..7d6f7d96b039 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -67,6 +67,21 @@ extern struct kobj_attribute shmem_enabled_attr;
 #define HPAGE_PMD_ORDER (HPAGE_PMD_SHIFT-PAGE_SHIFT)
 #define HPAGE_PMD_NR (1<<HPAGE_PMD_ORDER)
 
+/*
+ * Mask of all large folio orders supported for anonymous THP.
+ */
+#define THP_ORDERS_ALL_ANON	BIT(PMD_ORDER)
+
+/*
+ * Mask of all large folio orders supported for file THP.
+ */
+#define THP_ORDERS_ALL_FILE	(BIT(PMD_ORDER) | BIT(PUD_ORDER))
+
+/*
+ * Mask of all large folio orders supported for THP.
+ */
+#define THP_ORDERS_ALL		(THP_ORDERS_ALL_ANON | THP_ORDERS_ALL_FILE)
+
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 #define HPAGE_PMD_SHIFT PMD_SHIFT
 #define HPAGE_PMD_SIZE	((1UL) << HPAGE_PMD_SHIFT)
@@ -78,13 +93,18 @@ extern struct kobj_attribute shmem_enabled_attr;
 
 extern unsigned long transparent_hugepage_flags;
 
-#define hugepage_flags_enabled()					       \
-	(transparent_hugepage_flags &				       \
-	 ((1<<TRANSPARENT_HUGEPAGE_FLAG) |		       \
-	  (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)))
-#define hugepage_flags_always()				\
-	(transparent_hugepage_flags &			\
-	 (1<<TRANSPARENT_HUGEPAGE_FLAG))
+bool hugepage_flags_enabled(void);
+
+static inline int first_order(unsigned long orders)
+{
+	return fls_long(orders) - 1;
+}
+
+static inline int next_order(unsigned long *orders, int prev)
+{
+	*orders &= ~BIT(prev);
+	return first_order(*orders);
+}
 
 /*
  * Do the below checks:
@@ -97,23 +117,39 @@ extern unsigned long transparent_hugepage_flags;
  *   - For all vmas, check if the haddr is in an aligned HPAGE_PMD_SIZE
  *     area.
  */
-static inline bool transhuge_vma_suitable(struct vm_area_struct *vma,
-		unsigned long addr)
-{
-	unsigned long haddr;
-
-	/* Don't have to check pgoff for anonymous vma */
-	if (!vma_is_anonymous(vma)) {
-		if (!IS_ALIGNED((vma->vm_start >> PAGE_SHIFT) - vma->vm_pgoff,
-				HPAGE_PMD_NR))
-			return false;
+static inline unsigned long transhuge_vma_suitable(struct vm_area_struct *vma,
+		unsigned long addr, unsigned long orders)
+{
+	int order;
+
+	/*
+	 * Iterate over orders, highest to lowest, removing orders that don't
+	 * meet alignment requirements from the set. Exit loop at first order
+	 * that meets requirements, since all lower orders must also meet
+	 * requirements.
+	 */
+
+	order = first_order(orders);
+
+	while (orders) {
+		unsigned long hpage_size = PAGE_SIZE << order;
+		unsigned long haddr = ALIGN_DOWN(addr, hpage_size);
+
+		if (haddr >= vma->vm_start &&
+		    haddr + hpage_size <= vma->vm_end) {
+			if (!vma_is_anonymous(vma)) {
+				if (IS_ALIGNED((vma->vm_start >> PAGE_SHIFT) -
+						vma->vm_pgoff,
+						hpage_size >> PAGE_SHIFT))
+					break;
+			} else
+				break;
+		}
+
+		order = next_order(&orders, order);
 	}
 
-	haddr = addr & HPAGE_PMD_MASK;
-
-	if (haddr < vma->vm_start || haddr + HPAGE_PMD_SIZE > vma->vm_end)
-		return false;
-	return true;
+	return orders;
 }
 
 static inline bool file_thp_enabled(struct vm_area_struct *vma)
@@ -130,8 +166,9 @@ static inline bool file_thp_enabled(struct vm_area_struct *vma)
 	       !inode_is_open_for_write(inode) && S_ISREG(inode->i_mode);
 }
 
-bool hugepage_vma_check(struct vm_area_struct *vma, unsigned long vm_flags,
-			bool smaps, bool in_pf, bool enforce_sysfs);
+unsigned long hugepage_vma_check(struct vm_area_struct *vma,
+				 unsigned long vm_flags, bool smaps, bool in_pf,
+				 bool enforce_sysfs, unsigned long orders);
 
 #define transparent_hugepage_use_zero_page()				\
 	(transparent_hugepage_flags &					\
@@ -267,17 +304,18 @@ static inline bool folio_test_pmd_mappable(struct folio *folio)
 	return false;
 }
 
-static inline bool transhuge_vma_suitable(struct vm_area_struct *vma,
-		unsigned long addr)
+static inline unsigned long transhuge_vma_suitable(struct vm_area_struct *vma,
+		unsigned long addr, unsigned long orders)
 {
-	return false;
+	return 0;
 }
 
-static inline bool hugepage_vma_check(struct vm_area_struct *vma,
-				      unsigned long vm_flags, bool smaps,
-				      bool in_pf, bool enforce_sysfs)
+static inline unsigned long hugepage_vma_check(struct vm_area_struct *vma,
+					unsigned long vm_flags, bool smaps,
+					bool in_pf, bool enforce_sysfs,
+					unsigned long orders)
 {
-	return false;
+	return 0;
 }
 
 static inline void folio_prep_large_rmappable(struct folio *folio) {}
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 6eb55f97a3d2..0b545d56420c 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -74,12 +74,60 @@ static unsigned long deferred_split_scan(struct shrinker *shrink,
 static atomic_t huge_zero_refcount;
 struct page *huge_zero_page __read_mostly;
 unsigned long huge_zero_pfn __read_mostly = ~0UL;
+static unsigned long huge_anon_orders_always __read_mostly;
+static unsigned long huge_anon_orders_madvise __read_mostly;
+static unsigned long huge_anon_orders_global __read_mostly;
 
-bool hugepage_vma_check(struct vm_area_struct *vma, unsigned long vm_flags,
-			bool smaps, bool in_pf, bool enforce_sysfs)
+#define hugepage_global_enabled()			\
+	(transparent_hugepage_flags &			\
+	 ((1<<TRANSPARENT_HUGEPAGE_FLAG) |		\
+	  (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)))
+
+#define hugepage_global_always()			\
+	(transparent_hugepage_flags &			\
+	 (1<<TRANSPARENT_HUGEPAGE_FLAG))
+
+bool hugepage_flags_enabled(void)
 {
+	/*
+	 * We cover both the anon and the file-backed case here; we must return
+	 * true if globally enabled, even when all anon sizes are set to never.
+	 * So we don't need to look at huge_anon_orders_global.
+	 */
+	return hugepage_global_enabled() ||
+	       huge_anon_orders_always ||
+	       huge_anon_orders_madvise;
+}
+
+/**
+ * hugepage_vma_check - determine which hugepage orders can be applied to vma
+ * @vma:  the vm area to check
+ * @vm_flags: use these vm_flags instead of vma->vm_flags
+ * @smaps: whether answer will be used for smaps file
+ * @in_pf: whether answer will be used by page fault handler
+ * @enforce_sysfs: whether sysfs config should be taken into account
+ * @orders: bitfield of all orders to consider
+ *
+ * Calculates the intersection of the requested hugepage orders and the allowed
+ * hugepage orders for the provided vma. Permitted orders are encoded as a set
+ * bit at the corresponding bit position (bit-2 corresponds to order-2, bit-3
+ * corresponds to order-3, etc). Order-0 is never considered a hugepage order.
+ *
+ * Return: bitfield of orders allowed for hugepage in the vma. 0 if no hugepage
+ * orders are allowed.
+ */
+unsigned long hugepage_vma_check(struct vm_area_struct *vma,
+				 unsigned long vm_flags, bool smaps, bool in_pf,
+				 bool enforce_sysfs, unsigned long orders)
+{
+	/* Check the intersection of requested and supported orders. */
+	orders &= vma_is_anonymous(vma) ?
+			THP_ORDERS_ALL_ANON : THP_ORDERS_ALL_FILE;
+	if (!orders)
+		return 0;
+
 	if (!vma->vm_mm)		/* vdso */
-		return false;
+		return 0;
 
 	/*
 	 * Explicitly disabled through madvise or prctl, or some
@@ -88,16 +136,16 @@ bool hugepage_vma_check(struct vm_area_struct *vma, unsigned long vm_flags,
 	 * */
 	if ((vm_flags & VM_NOHUGEPAGE) ||
 	    test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags))
-		return false;
+		return 0;
 	/*
 	 * If the hardware/firmware marked hugepage support disabled.
 	 */
 	if (transparent_hugepage_flags & (1 << TRANSPARENT_HUGEPAGE_UNSUPPORTED))
-		return false;
+		return 0;
 
 	/* khugepaged doesn't collapse DAX vma, but page fault is fine. */
 	if (vma_is_dax(vma))
-		return in_pf;
+		return in_pf ? orders : 0;
 
 	/*
 	 * khugepaged special VMA and hugetlb VMA.
@@ -105,17 +153,29 @@ bool hugepage_vma_check(struct vm_area_struct *vma, unsigned long vm_flags,
 	 * VM_MIXEDMAP set.
 	 */
 	if (!in_pf && !smaps && (vm_flags & VM_NO_KHUGEPAGED))
-		return false;
+		return 0;
 
 	/*
-	 * Check alignment for file vma and size for both file and anon vma.
+	 * Check alignment for file vma and size for both file and anon vma by
+	 * filtering out the unsuitable orders.
 	 *
 	 * Skip the check for page fault. Huge fault does the check in fault
-	 * handlers. And this check is not suitable for huge PUD fault.
+	 * handlers.
 	 */
-	if (!in_pf &&
-	    !transhuge_vma_suitable(vma, (vma->vm_end - HPAGE_PMD_SIZE)))
-		return false;
+	if (!in_pf) {
+		int order = first_order(orders);
+		unsigned long addr;
+
+		while (orders) {
+			addr = vma->vm_end - (PAGE_SIZE << order);
+			if (transhuge_vma_suitable(vma, addr, BIT(order)))
+				break;
+			order = next_order(&orders, order);
+		}
+
+		if (!orders)
+			return 0;
+	}
 
 	/*
 	 * Enabled via shmem mount options or sysfs settings.
@@ -124,13 +184,27 @@ bool hugepage_vma_check(struct vm_area_struct *vma, unsigned long vm_flags,
 	 */
 	if (!in_pf && shmem_file(vma->vm_file))
 		return shmem_is_huge(file_inode(vma->vm_file), vma->vm_pgoff,
-				     !enforce_sysfs, vma->vm_mm, vm_flags);
+				     !enforce_sysfs, vma->vm_mm, vm_flags)
+			? orders : 0;
 
 	/* Enforce sysfs THP requirements as necessary */
-	if (enforce_sysfs &&
-	    (!hugepage_flags_enabled() || (!(vm_flags & VM_HUGEPAGE) &&
-					   !hugepage_flags_always())))
-		return false;
+	if (enforce_sysfs) {
+		if (vma_is_anonymous(vma)) {
+			unsigned long mask = READ_ONCE(huge_anon_orders_always);
+
+			if (vm_flags & VM_HUGEPAGE)
+				mask |= READ_ONCE(huge_anon_orders_madvise);
+			if (hugepage_global_always() ||
+			   ((vm_flags & VM_HUGEPAGE) && hugepage_global_enabled()))
+				mask |= READ_ONCE(huge_anon_orders_global);
+
+			orders &= mask;
+			if (!orders)
+				return 0;
+		} else if (!hugepage_global_enabled() ||
+			  (!(vm_flags & VM_HUGEPAGE) && !hugepage_global_always()))
+			return 0;
+	}
 
 	if (!vma_is_anonymous(vma)) {
 		/*
@@ -138,15 +212,15 @@ bool hugepage_vma_check(struct vm_area_struct *vma, unsigned long vm_flags,
 		 * in fault path.
 		 */
 		if (((in_pf || smaps)) && vma->vm_ops->huge_fault)
-			return true;
+			return orders;
 		/* Only regular file is valid in collapse path */
 		if (((!in_pf || smaps)) && file_thp_enabled(vma))
-			return true;
-		return false;
+			return orders;
+		return 0;
 	}
 
 	if (vma_is_temporary_stack(vma))
-		return false;
+		return 0;
 
 	/*
 	 * THPeligible bit of smaps should show 1 for proper VMAs even
@@ -156,9 +230,9 @@ bool hugepage_vma_check(struct vm_area_struct *vma, unsigned long vm_flags,
 	 * the first page fault.
 	 */
 	if (!vma->anon_vma)
-		return (smaps || in_pf);
+		return (smaps || in_pf) ? orders : 0;
 
-	return true;
+	return orders;
 }
 
 static bool get_huge_zero_page(void)
@@ -412,9 +486,127 @@ static const struct attribute_group hugepage_attr_group = {
 	.attrs = hugepage_attr,
 };
 
+static void hugepage_exit_sysfs(struct kobject *hugepage_kobj);
+static void thpsize_release(struct kobject *kobj);
+static LIST_HEAD(thpsize_list);
+
+struct thpsize {
+	struct kobject kobj;
+	struct list_head node;
+	int order;
+};
+
+#define to_thpsize(kobj) container_of(kobj, struct thpsize, kobj)
+
+static ssize_t thpsize_enabled_show(struct kobject *kobj,
+				    struct kobj_attribute *attr, char *buf)
+{
+	int order = to_thpsize(kobj)->order;
+	const char *output;
+
+	if (test_bit(order, &huge_anon_orders_always))
+		output = "[always] global madvise never";
+	else if (test_bit(order, &huge_anon_orders_global))
+		output = "always [global] madvise never";
+	else if (test_bit(order, &huge_anon_orders_madvise))
+		output = "always global [madvise] never";
+	else
+		output = "always global madvise [never]";
+
+	return sysfs_emit(buf, "%s\n", output);
+}
+
+static ssize_t thpsize_enabled_store(struct kobject *kobj,
+				     struct kobj_attribute *attr,
+				     const char *buf, size_t count)
+{
+	int order = to_thpsize(kobj)->order;
+	ssize_t ret = count;
+
+	if (sysfs_streq(buf, "always")) {
+		set_bit(order, &huge_anon_orders_always);
+		clear_bit(order, &huge_anon_orders_global);
+		clear_bit(order, &huge_anon_orders_madvise);
+	} else if (sysfs_streq(buf, "global")) {
+		set_bit(order, &huge_anon_orders_global);
+		clear_bit(order, &huge_anon_orders_always);
+		clear_bit(order, &huge_anon_orders_madvise);
+	} else if (sysfs_streq(buf, "madvise")) {
+		set_bit(order, &huge_anon_orders_madvise);
+		clear_bit(order, &huge_anon_orders_always);
+		clear_bit(order, &huge_anon_orders_global);
+	} else if (sysfs_streq(buf, "never")) {
+		clear_bit(order, &huge_anon_orders_always);
+		clear_bit(order, &huge_anon_orders_global);
+		clear_bit(order, &huge_anon_orders_madvise);
+	} else
+		ret = -EINVAL;
+
+	return ret;
+}
+
+static struct kobj_attribute thpsize_enabled_attr =
+	__ATTR(enabled, 0644, thpsize_enabled_show, thpsize_enabled_store);
+
+static struct attribute *thpsize_attrs[] = {
+	&thpsize_enabled_attr.attr,
+	NULL,
+};
+
+static const struct attribute_group thpsize_attr_group = {
+	.attrs = thpsize_attrs,
+};
+
+static const struct kobj_type thpsize_ktype = {
+	.release = &thpsize_release,
+	.sysfs_ops = &kobj_sysfs_ops,
+};
+
+static struct thpsize *thpsize_create(int order, struct kobject *parent)
+{
+	unsigned long size = (PAGE_SIZE << order) / SZ_1K;
+	struct thpsize *thpsize;
+	int ret;
+
+	thpsize = kzalloc(sizeof(*thpsize), GFP_KERNEL);
+	if (!thpsize)
+		return ERR_PTR(-ENOMEM);
+
+	ret = kobject_init_and_add(&thpsize->kobj, &thpsize_ktype, parent,
+				   "hugepages-%lukB", size);
+	if (ret) {
+		kfree(thpsize);
+		return ERR_PTR(ret);
+	}
+
+	ret = sysfs_create_group(&thpsize->kobj, &thpsize_attr_group);
+	if (ret) {
+		kobject_put(&thpsize->kobj);
+		return ERR_PTR(ret);
+	}
+
+	thpsize->order = order;
+	return thpsize;
+}
+
+static void thpsize_release(struct kobject *kobj)
+{
+	kfree(to_thpsize(kobj));
+}
+
 static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj)
 {
 	int err;
+	struct thpsize *thpsize;
+	unsigned long orders;
+	int order;
+
+	/*
+	 * Default to setting PMD-sized THP to follow the global setting and
+	 * disable all other sizes. powerpc's PMD_ORDER isn't a compile-time
+	 * constant so we have to do this here.
+	 */
+	huge_anon_orders_global = BIT(PMD_ORDER);
 
 	*hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj);
 	if (unlikely(!*hugepage_kobj)) {
@@ -434,8 +626,24 @@ static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj)
 		goto remove_hp_group;
 	}
 
+	orders = THP_ORDERS_ALL_ANON;
+	order = first_order(orders);
+	while (orders) {
+		thpsize = thpsize_create(order, *hugepage_kobj);
+		if (IS_ERR(thpsize)) {
+			pr_err("failed to create thpsize for order %d\n", order);
+			err = PTR_ERR(thpsize);
+			goto remove_all;
+		}
+		list_add(&thpsize->node, &thpsize_list);
+		order = next_order(&orders, order);
+	}
+
 	return 0;
 
+remove_all:
+	hugepage_exit_sysfs(*hugepage_kobj);
+	return err;
 remove_hp_group:
 	sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group);
 delete_obj:
@@ -445,6 +653,13 @@ static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj)
 
 static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj)
 {
+	struct thpsize *thpsize, *tmp;
+
+	list_for_each_entry_safe(thpsize, tmp, &thpsize_list, node) {
+		list_del(&thpsize->node);
+		kobject_put(&thpsize->kobj);
+	}
+
 	sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group);
 	sysfs_remove_group(hugepage_kobj, &hugepage_attr_group);
 	kobject_put(hugepage_kobj);
@@ -811,7 +1026,7 @@ vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf)
 	struct folio *folio;
 	unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
 
-	if (!transhuge_vma_suitable(vma, haddr))
+	if (!transhuge_vma_suitable(vma, haddr, BIT(PMD_ORDER)))
 		return VM_FAULT_FALLBACK;
 	if (unlikely(anon_vma_prepare(vma)))
 		return VM_FAULT_OOM;
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 064654717843..c3a874c0d601 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -446,7 +446,8 @@ void khugepaged_enter_vma(struct vm_area_struct *vma,
 {
 	if (!test_bit(MMF_VM_HUGEPAGE, &vma->vm_mm->flags) &&
 	    hugepage_flags_enabled()) {
-		if (hugepage_vma_check(vma, vm_flags, false, false, true))
+		if (hugepage_vma_check(vma, vm_flags, false, false, true,
+				       BIT(PMD_ORDER)))
 			__khugepaged_enter(vma->vm_mm);
 	}
 }
@@ -922,10 +923,10 @@ static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address,
 	if (!vma)
 		return SCAN_VMA_NULL;
 
-	if (!transhuge_vma_suitable(vma, address))
+	if (!transhuge_vma_suitable(vma, address, BIT(PMD_ORDER)))
 		return SCAN_ADDRESS_RANGE;
 	if (!hugepage_vma_check(vma, vma->vm_flags, false, false,
-				cc->is_khugepaged))
+				cc->is_khugepaged, BIT(PMD_ORDER)))
 		return SCAN_VMA_CHECK;
 	/*
 	 * Anon VMA expected, the address may be unmapped then
@@ -1503,7 +1504,8 @@ int collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr,
 	 * and map it by a PMD, regardless of sysfs THP settings. As such, let's
 	 * analogously elide sysfs THP settings here.
 	 */
-	if (!hugepage_vma_check(vma, vma->vm_flags, false, false, false))
+	if (!hugepage_vma_check(vma, vma->vm_flags, false, false, false,
+				BIT(PMD_ORDER)))
 		return SCAN_VMA_CHECK;
 
 	/* Keep pmd pgtable for uffd-wp; see comment in retract_page_tables() */
@@ -2368,7 +2370,8 @@ static unsigned int khugepaged_scan_mm_slot(unsigned int pages, int *result,
 			progress++;
 			break;
 		}
-		if (!hugepage_vma_check(vma, vma->vm_flags, false, false, true)) {
+		if (!hugepage_vma_check(vma, vma->vm_flags, false, false, true,
+					BIT(PMD_ORDER))) {
 skip:
 			progress++;
 			continue;
@@ -2705,7 +2708,8 @@ int madvise_collapse(struct vm_area_struct *vma, struct vm_area_struct **prev,
 
 	*prev = vma;
 
-	if (!hugepage_vma_check(vma, vma->vm_flags, false, false, false))
+	if (!hugepage_vma_check(vma, vma->vm_flags, false, false, false,
+				BIT(PMD_ORDER)))
 		return -EINVAL;
 
 	cc = kmalloc(sizeof(*cc), GFP_KERNEL);
diff --git a/mm/memory.c b/mm/memory.c
index c32954e16b28..9d5e61d6d859 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -4319,7 +4319,7 @@ vm_fault_t do_set_pmd(struct vm_fault *vmf, struct page *page)
 	pmd_t entry;
 	vm_fault_t ret = VM_FAULT_FALLBACK;
 
-	if (!transhuge_vma_suitable(vma, haddr))
+	if (!transhuge_vma_suitable(vma, haddr, BIT(PMD_ORDER)))
 		return ret;
 
 	page = compound_head(page);
@@ -5117,7 +5117,7 @@ static vm_fault_t __handle_mm_fault(struct vm_area_struct *vma,
 		return VM_FAULT_OOM;
 retry_pud:
 	if (pud_none(*vmf.pud) &&
-	    hugepage_vma_check(vma, vm_flags, false, true, true)) {
+	    hugepage_vma_check(vma, vm_flags, false, true, true, BIT(PUD_ORDER))) {
 		ret = create_huge_pud(&vmf);
 		if (!(ret & VM_FAULT_FALLBACK))
 			return ret;
@@ -5151,7 +5151,7 @@ static vm_fault_t __handle_mm_fault(struct vm_area_struct *vma,
 		goto retry_pud;
 
 	if (pmd_none(*vmf.pmd) &&
-	    hugepage_vma_check(vma, vm_flags, false, true, true)) {
+	    hugepage_vma_check(vma, vm_flags, false, true, true, BIT(PMD_ORDER))) {
 		ret = create_huge_pmd(&vmf);
 		if (!(ret & VM_FAULT_FALLBACK))
 			return ret;
diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c
index e0b368e545ed..5f7e89c5b595 100644
--- a/mm/page_vma_mapped.c
+++ b/mm/page_vma_mapped.c
@@ -268,7 +268,8 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw)
 			 * cleared *pmd but not decremented compound_mapcount().
 			 */
 			if ((pvmw->flags & PVMW_SYNC) &&
-			    transhuge_vma_suitable(vma, pvmw->address) &&
+			    transhuge_vma_suitable(vma, pvmw->address,
+						   BIT(PMD_ORDER)) &&
 			    (pvmw->nr_pages >= HPAGE_PMD_NR)) {
 				spinlock_t *ptl = pmd_lock(mm, pvmw->pmd);
 
-- 
2.25.1

[PATCH v7 04/10] mm: thp: Support allocation of anonymous small-sized THP

[Ryan Roberts]

Introduce the logic to allow THP to be configured (through the new sysfs
interface we just added) to allocate large folios to back anonymous
memory, which are smaller than PMD-size. We call this new THP type
"small-sized THP".

These small-sized THPs continue to be PTE-mapped, but in many cases can
still provide similar benefits to traditional PMD-sized THP: Page faults
are significantly reduced (by a factor of e.g. 4, 8, 16, etc. depending
on the configured order), but latency spikes are much less prominent
because the size of each page isn't as huge as the PMD-sized variant and
there is less memory to clear in each page fault. The number of per-page
operations (e.g. ref counting, rmap management, lru list management) are
also significantly reduced since those ops now become per-folio.

Some architectures also employ TLB compression mechanisms to squeeze
more entries in when a set of PTEs are virtually and physically
contiguous and approporiately aligned. In this case, TLB misses will
occur less often.

The new behaviour is disabled by default, but can be enabled at runtime
by writing to /sys/kernel/mm/transparent_hugepage/hugepage-XXkb/enabled
(see documentation in previous commit). The long term aim is to change
the default to include suitable lower orders, but there are some risks
around internal fragmentation that need to be better understood first.

Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
---
 include/linux/huge_mm.h |   6 ++-
 mm/memory.c             | 106 ++++++++++++++++++++++++++++++++++++----
 2 files changed, 101 insertions(+), 11 deletions(-)

diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index 7d6f7d96b039..edc302351971 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -68,9 +68,11 @@ extern struct kobj_attribute shmem_enabled_attr;
 #define HPAGE_PMD_NR (1<<HPAGE_PMD_ORDER)
 
 /*
- * Mask of all large folio orders supported for anonymous THP.
+ * Mask of all large folio orders supported for anonymous THP; all orders up to
+ * and including PMD_ORDER, except order-0 (which is not "huge") and order-1
+ * (which is a limitation of the THP implementation).
  */
-#define THP_ORDERS_ALL_ANON	BIT(PMD_ORDER)
+#define THP_ORDERS_ALL_ANON	((BIT(PMD_ORDER + 1) - 1) & ~(BIT(0) | BIT(1)))
 
 /*
  * Mask of all large folio orders supported for file THP.
diff --git a/mm/memory.c b/mm/memory.c
index 9d5e61d6d859..8fbe302aac3f 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -4122,6 +4122,84 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
 	return ret;
 }
 
+static bool pte_range_none(pte_t *pte, int nr_pages)
+{
+	int i;
+
+	for (i = 0; i < nr_pages; i++) {
+		if (!pte_none(ptep_get_lockless(pte + i)))
+			return false;
+	}
+
+	return true;
+}
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+static struct folio *alloc_anon_folio(struct vm_fault *vmf)
+{
+	gfp_t gfp;
+	pte_t *pte;
+	unsigned long addr;
+	struct folio *folio;
+	struct vm_area_struct *vma = vmf->vma;
+	unsigned long orders;
+	int order;
+
+	/*
+	 * If uffd is active for the vma we need per-page fault fidelity to
+	 * maintain the uffd semantics.
+	 */
+	if (userfaultfd_armed(vma))
+		goto fallback;
+
+	/*
+	 * Get a list of all the (large) orders below PMD_ORDER that are enabled
+	 * for this vma. Then filter out the orders that can't be allocated over
+	 * the faulting address and still be fully contained in the vma.
+	 */
+	orders = hugepage_vma_check(vma, vma->vm_flags, false, true, true,
+				    BIT(PMD_ORDER) - 1);
+	orders = transhuge_vma_suitable(vma, vmf->address, orders);
+
+	if (!orders)
+		goto fallback;
+
+	pte = pte_offset_map(vmf->pmd, vmf->address & PMD_MASK);
+	if (!pte)
+		return ERR_PTR(-EAGAIN);
+
+	order = first_order(orders);
+	while (orders) {
+		addr = ALIGN_DOWN(vmf->address, PAGE_SIZE << order);
+		vmf->pte = pte + pte_index(addr);
+		if (pte_range_none(vmf->pte, 1 << order))
+			break;
+		order = next_order(&orders, order);
+	}
+
+	vmf->pte = NULL;
+	pte_unmap(pte);
+
+	gfp = vma_thp_gfp_mask(vma);
+
+	while (orders) {
+		addr = ALIGN_DOWN(vmf->address, PAGE_SIZE << order);
+		folio = vma_alloc_folio(gfp, order, vma, addr, true);
+		if (folio) {
+			clear_huge_page(&folio->page, addr, 1 << order);
+			return folio;
+		}
+		order = next_order(&orders, order);
+	}
+
+fallback:
+	return vma_alloc_zeroed_movable_folio(vma, vmf->address);
+}
+#else
+#define alloc_anon_folio(vmf) \
+		vma_alloc_zeroed_movable_folio((vmf)->vma, (vmf)->address)
+#endif
+
 /*
  * We enter with non-exclusive mmap_lock (to exclude vma changes,
  * but allow concurrent faults), and pte mapped but not yet locked.
@@ -4129,6 +4207,9 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
  */
 static vm_fault_t do_anonymous_page(struct vm_fault *vmf)
 {
+	int i;
+	int nr_pages = 1;
+	unsigned long addr = vmf->address;
 	bool uffd_wp = vmf_orig_pte_uffd_wp(vmf);
 	struct vm_area_struct *vma = vmf->vma;
 	struct folio *folio;
@@ -4173,10 +4254,15 @@ static vm_fault_t do_anonymous_page(struct vm_fault *vmf)
 	/* Allocate our own private page. */
 	if (unlikely(anon_vma_prepare(vma)))
 		goto oom;
-	folio = vma_alloc_zeroed_movable_folio(vma, vmf->address);
+	folio = alloc_anon_folio(vmf);
+	if (IS_ERR(folio))
+		return 0;
 	if (!folio)
 		goto oom;
 
+	nr_pages = folio_nr_pages(folio);
+	addr = ALIGN_DOWN(vmf->address, nr_pages * PAGE_SIZE);
+
 	if (mem_cgroup_charge(folio, vma->vm_mm, GFP_KERNEL))
 		goto oom_free_page;
 	folio_throttle_swaprate(folio, GFP_KERNEL);
@@ -4193,12 +4279,13 @@ static vm_fault_t do_anonymous_page(struct vm_fault *vmf)
 	if (vma->vm_flags & VM_WRITE)
 		entry = pte_mkwrite(pte_mkdirty(entry), vma);
 
-	vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
-			&vmf->ptl);
+	vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, addr, &vmf->ptl);
 	if (!vmf->pte)
 		goto release;
-	if (vmf_pte_changed(vmf)) {
-		update_mmu_tlb(vma, vmf->address, vmf->pte);
+	if ((nr_pages == 1 && vmf_pte_changed(vmf)) ||
+	    (nr_pages  > 1 && !pte_range_none(vmf->pte, nr_pages))) {
+		for (i = 0; i < nr_pages; i++)
+			update_mmu_tlb(vma, addr + PAGE_SIZE * i, vmf->pte + i);
 		goto release;
 	}
 
@@ -4213,16 +4300,17 @@ static vm_fault_t do_anonymous_page(struct vm_fault *vmf)
 		return handle_userfault(vmf, VM_UFFD_MISSING);
 	}
 
-	inc_mm_counter(vma->vm_mm, MM_ANONPAGES);
-	folio_add_new_anon_rmap(folio, vma, vmf->address);
+	folio_ref_add(folio, nr_pages - 1);
+	add_mm_counter(vma->vm_mm, MM_ANONPAGES, nr_pages);
+	folio_add_new_anon_rmap(folio, vma, addr);
 	folio_add_lru_vma(folio, vma);
 setpte:
 	if (uffd_wp)
 		entry = pte_mkuffd_wp(entry);
-	set_pte_at(vma->vm_mm, vmf->address, vmf->pte, entry);
+	set_ptes(vma->vm_mm, addr, vmf->pte, entry, nr_pages);
 
 	/* No need to invalidate - it was non-present before */
-	update_mmu_cache_range(vmf, vma, vmf->address, vmf->pte, 1);
+	update_mmu_cache_range(vmf, vma, addr, vmf->pte, nr_pages);
 unlock:
 	if (vmf->pte)
 		pte_unmap_unlock(vmf->pte, vmf->ptl);
-- 
2.25.1

[PATCH v7 05/10] selftests/mm/kugepaged: Restore thp settings at exit

[Ryan Roberts]

Previously, the saved thp settings would be restored upon a signal or at
the natural end of the test suite. But there are some tests that
directly call exit() upon failure. In this case, the thp settings were
not being restored, which could then influence other tests.

Fix this by installing an atexit() handler to do the actual restore. The
signal handler can now just call exit() and the atexit handler is
invoked.

Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
---
 tools/testing/selftests/mm/khugepaged.c | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/tools/testing/selftests/mm/khugepaged.c b/tools/testing/selftests/mm/khugepaged.c
index 030667cb5533..fc47a1c4944c 100644
--- a/tools/testing/selftests/mm/khugepaged.c
+++ b/tools/testing/selftests/mm/khugepaged.c
@@ -374,18 +374,22 @@ static void pop_settings(void)
 	write_settings(current_settings());
 }
 
-static void restore_settings(int sig)
+static void restore_settings_atexit(void)
 {
 	if (skip_settings_restore)
-		goto out;
+		return;
 
 	printf("Restore THP and khugepaged settings...");
 	write_settings(&saved_settings);
 	success("OK");
-	if (sig)
-		exit(EXIT_FAILURE);
-out:
-	exit(exit_status);
+
+	skip_settings_restore = true;
+}
+
+static void restore_settings(int sig)
+{
+	/* exit() will invoke the restore_settings_atexit handler. */
+	exit(sig ? EXIT_FAILURE : exit_status);
 }
 
 static void save_settings(void)
@@ -415,6 +419,7 @@ static void save_settings(void)
 
 	success("OK");
 
+	atexit(restore_settings_atexit);
 	signal(SIGTERM, restore_settings);
 	signal(SIGINT, restore_settings);
 	signal(SIGHUP, restore_settings);
-- 
2.25.1

[PATCH v7 06/10] selftests/mm: Factor out thp settings management

[Ryan Roberts]

The khugepaged test has a useful framework for save/restore/pop/push of
all thp settings via the sysfs interface. This will be useful to
explicitly control small-sized THP settings in other tests, so let's
move it out of khugepaged and into its own thp_settings.[c|h] utility.

Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
---
 tools/testing/selftests/mm/Makefile       |   4 +-
 tools/testing/selftests/mm/khugepaged.c   | 346 ++--------------------
 tools/testing/selftests/mm/thp_settings.c | 296 ++++++++++++++++++
 tools/testing/selftests/mm/thp_settings.h |  71 +++++
 4 files changed, 391 insertions(+), 326 deletions(-)
 create mode 100644 tools/testing/selftests/mm/thp_settings.c
 create mode 100644 tools/testing/selftests/mm/thp_settings.h

diff --git a/tools/testing/selftests/mm/Makefile b/tools/testing/selftests/mm/Makefile
index 78dfec8bc676..a3eb20c186e7 100644
--- a/tools/testing/selftests/mm/Makefile
+++ b/tools/testing/selftests/mm/Makefile
@@ -117,8 +117,8 @@ TEST_FILES += va_high_addr_switch.sh
 
 include ../lib.mk
 
-$(TEST_GEN_PROGS): vm_util.c
-$(TEST_GEN_FILES): vm_util.c
+$(TEST_GEN_PROGS): vm_util.c thp_settings.c
+$(TEST_GEN_FILES): vm_util.c thp_settings.c
 
 $(OUTPUT)/uffd-stress: uffd-common.c
 $(OUTPUT)/uffd-unit-tests: uffd-common.c
diff --git a/tools/testing/selftests/mm/khugepaged.c b/tools/testing/selftests/mm/khugepaged.c
index fc47a1c4944c..b15e7fd70176 100644
--- a/tools/testing/selftests/mm/khugepaged.c
+++ b/tools/testing/selftests/mm/khugepaged.c
@@ -22,13 +22,13 @@
 #include "linux/magic.h"
 
 #include "vm_util.h"
+#include "thp_settings.h"
 
 #define BASE_ADDR ((void *)(1UL << 30))
 static unsigned long hpage_pmd_size;
 static unsigned long page_size;
 static int hpage_pmd_nr;
 
-#define THP_SYSFS "/sys/kernel/mm/transparent_hugepage/"
 #define PID_SMAPS "/proc/self/smaps"
 #define TEST_FILE "collapse_test_file"
 
@@ -71,78 +71,7 @@ struct file_info {
 };
 
 static struct file_info finfo;
-
-enum thp_enabled {
-	THP_ALWAYS,
-	THP_MADVISE,
-	THP_NEVER,
-};
-
-static const char *thp_enabled_strings[] = {
-	"always",
-	"madvise",
-	"never",
-	NULL
-};
-
-enum thp_defrag {
-	THP_DEFRAG_ALWAYS,
-	THP_DEFRAG_DEFER,
-	THP_DEFRAG_DEFER_MADVISE,
-	THP_DEFRAG_MADVISE,
-	THP_DEFRAG_NEVER,
-};
-
-static const char *thp_defrag_strings[] = {
-	"always",
-	"defer",
-	"defer+madvise",
-	"madvise",
-	"never",
-	NULL
-};
-
-enum shmem_enabled {
-	SHMEM_ALWAYS,
-	SHMEM_WITHIN_SIZE,
-	SHMEM_ADVISE,
-	SHMEM_NEVER,
-	SHMEM_DENY,
-	SHMEM_FORCE,
-};
-
-static const char *shmem_enabled_strings[] = {
-	"always",
-	"within_size",
-	"advise",
-	"never",
-	"deny",
-	"force",
-	NULL
-};
-
-struct khugepaged_settings {
-	bool defrag;
-	unsigned int alloc_sleep_millisecs;
-	unsigned int scan_sleep_millisecs;
-	unsigned int max_ptes_none;
-	unsigned int max_ptes_swap;
-	unsigned int max_ptes_shared;
-	unsigned long pages_to_scan;
-};
-
-struct settings {
-	enum thp_enabled thp_enabled;
-	enum thp_defrag thp_defrag;
-	enum shmem_enabled shmem_enabled;
-	bool use_zero_page;
-	struct khugepaged_settings khugepaged;
-	unsigned long read_ahead_kb;
-};
-
-static struct settings saved_settings;
 static bool skip_settings_restore;
-
 static int exit_status;
 
 static void success(const char *msg)
@@ -161,226 +90,13 @@ static void skip(const char *msg)
 	printf(" \e[33m%s\e[0m\n", msg);
 }
 
-static int read_file(const char *path, char *buf, size_t buflen)
-{
-	int fd;
-	ssize_t numread;
-
-	fd = open(path, O_RDONLY);
-	if (fd == -1)
-		return 0;
-
-	numread = read(fd, buf, buflen - 1);
-	if (numread < 1) {
-		close(fd);
-		return 0;
-	}
-
-	buf[numread] = '\0';
-	close(fd);
-
-	return (unsigned int) numread;
-}
-
-static int write_file(const char *path, const char *buf, size_t buflen)
-{
-	int fd;
-	ssize_t numwritten;
-
-	fd = open(path, O_WRONLY);
-	if (fd == -1) {
-		printf("open(%s)\n", path);
-		exit(EXIT_FAILURE);
-		return 0;
-	}
-
-	numwritten = write(fd, buf, buflen - 1);
-	close(fd);
-	if (numwritten < 1) {
-		printf("write(%s)\n", buf);
-		exit(EXIT_FAILURE);
-		return 0;
-	}
-
-	return (unsigned int) numwritten;
-}
-
-static int read_string(const char *name, const char *strings[])
-{
-	char path[PATH_MAX];
-	char buf[256];
-	char *c;
-	int ret;
-
-	ret = snprintf(path, PATH_MAX, THP_SYSFS "%s", name);
-	if (ret >= PATH_MAX) {
-		printf("%s: Pathname is too long\n", __func__);
-		exit(EXIT_FAILURE);
-	}
-
-	if (!read_file(path, buf, sizeof(buf))) {
-		perror(path);
-		exit(EXIT_FAILURE);
-	}
-
-	c = strchr(buf, '[');
-	if (!c) {
-		printf("%s: Parse failure\n", __func__);
-		exit(EXIT_FAILURE);
-	}
-
-	c++;
-	memmove(buf, c, sizeof(buf) - (c - buf));
-
-	c = strchr(buf, ']');
-	if (!c) {
-		printf("%s: Parse failure\n", __func__);
-		exit(EXIT_FAILURE);
-	}
-	*c = '\0';
-
-	ret = 0;
-	while (strings[ret]) {
-		if (!strcmp(strings[ret], buf))
-			return ret;
-		ret++;
-	}
-
-	printf("Failed to parse %s\n", name);
-	exit(EXIT_FAILURE);
-}
-
-static void write_string(const char *name, const char *val)
-{
-	char path[PATH_MAX];
-	int ret;
-
-	ret = snprintf(path, PATH_MAX, THP_SYSFS "%s", name);
-	if (ret >= PATH_MAX) {
-		printf("%s: Pathname is too long\n", __func__);
-		exit(EXIT_FAILURE);
-	}
-
-	if (!write_file(path, val, strlen(val) + 1)) {
-		perror(path);
-		exit(EXIT_FAILURE);
-	}
-}
-
-static const unsigned long _read_num(const char *path)
-{
-	char buf[21];
-
-	if (read_file(path, buf, sizeof(buf)) < 0) {
-		perror("read_file(read_num)");
-		exit(EXIT_FAILURE);
-	}
-
-	return strtoul(buf, NULL, 10);
-}
-
-static const unsigned long read_num(const char *name)
-{
-	char path[PATH_MAX];
-	int ret;
-
-	ret = snprintf(path, PATH_MAX, THP_SYSFS "%s", name);
-	if (ret >= PATH_MAX) {
-		printf("%s: Pathname is too long\n", __func__);
-		exit(EXIT_FAILURE);
-	}
-	return _read_num(path);
-}
-
-static void _write_num(const char *path, unsigned long num)
-{
-	char buf[21];
-
-	sprintf(buf, "%ld", num);
-	if (!write_file(path, buf, strlen(buf) + 1)) {
-		perror(path);
-		exit(EXIT_FAILURE);
-	}
-}
-
-static void write_num(const char *name, unsigned long num)
-{
-	char path[PATH_MAX];
-	int ret;
-
-	ret = snprintf(path, PATH_MAX, THP_SYSFS "%s", name);
-	if (ret >= PATH_MAX) {
-		printf("%s: Pathname is too long\n", __func__);
-		exit(EXIT_FAILURE);
-	}
-	_write_num(path, num);
-}
-
-static void write_settings(struct settings *settings)
-{
-	struct khugepaged_settings *khugepaged = &settings->khugepaged;
-
-	write_string("enabled", thp_enabled_strings[settings->thp_enabled]);
-	write_string("defrag", thp_defrag_strings[settings->thp_defrag]);
-	write_string("shmem_enabled",
-			shmem_enabled_strings[settings->shmem_enabled]);
-	write_num("use_zero_page", settings->use_zero_page);
-
-	write_num("khugepaged/defrag", khugepaged->defrag);
-	write_num("khugepaged/alloc_sleep_millisecs",
-			khugepaged->alloc_sleep_millisecs);
-	write_num("khugepaged/scan_sleep_millisecs",
-			khugepaged->scan_sleep_millisecs);
-	write_num("khugepaged/max_ptes_none", khugepaged->max_ptes_none);
-	write_num("khugepaged/max_ptes_swap", khugepaged->max_ptes_swap);
-	write_num("khugepaged/max_ptes_shared", khugepaged->max_ptes_shared);
-	write_num("khugepaged/pages_to_scan", khugepaged->pages_to_scan);
-
-	if (file_ops && finfo.type == VMA_FILE)
-		_write_num(finfo.dev_queue_read_ahead_path,
-			   settings->read_ahead_kb);
-}
-
-#define MAX_SETTINGS_DEPTH 4
-static struct settings settings_stack[MAX_SETTINGS_DEPTH];
-static int settings_index;
-
-static struct settings *current_settings(void)
-{
-	if (!settings_index) {
-		printf("Fail: No settings set");
-		exit(EXIT_FAILURE);
-	}
-	return settings_stack + settings_index - 1;
-}
-
-static void push_settings(struct settings *settings)
-{
-	if (settings_index >= MAX_SETTINGS_DEPTH) {
-		printf("Fail: Settings stack exceeded");
-		exit(EXIT_FAILURE);
-	}
-	settings_stack[settings_index++] = *settings;
-	write_settings(current_settings());
-}
-
-static void pop_settings(void)
-{
-	if (settings_index <= 0) {
-		printf("Fail: Settings stack empty");
-		exit(EXIT_FAILURE);
-	}
-	--settings_index;
-	write_settings(current_settings());
-}
-
 static void restore_settings_atexit(void)
 {
 	if (skip_settings_restore)
 		return;
 
 	printf("Restore THP and khugepaged settings...");
-	write_settings(&saved_settings);
+	thp_restore_settings();
 	success("OK");
 
 	skip_settings_restore = true;
@@ -395,27 +111,9 @@ static void restore_settings(int sig)
 static void save_settings(void)
 {
 	printf("Save THP and khugepaged settings...");
-	saved_settings = (struct settings) {
-		.thp_enabled = read_string("enabled", thp_enabled_strings),
-		.thp_defrag = read_string("defrag", thp_defrag_strings),
-		.shmem_enabled =
-			read_string("shmem_enabled", shmem_enabled_strings),
-		.use_zero_page = read_num("use_zero_page"),
-	};
-	saved_settings.khugepaged = (struct khugepaged_settings) {
-		.defrag = read_num("khugepaged/defrag"),
-		.alloc_sleep_millisecs =
-			read_num("khugepaged/alloc_sleep_millisecs"),
-		.scan_sleep_millisecs =
-			read_num("khugepaged/scan_sleep_millisecs"),
-		.max_ptes_none = read_num("khugepaged/max_ptes_none"),
-		.max_ptes_swap = read_num("khugepaged/max_ptes_swap"),
-		.max_ptes_shared = read_num("khugepaged/max_ptes_shared"),
-		.pages_to_scan = read_num("khugepaged/pages_to_scan"),
-	};
 	if (file_ops && finfo.type == VMA_FILE)
-		saved_settings.read_ahead_kb =
-				_read_num(finfo.dev_queue_read_ahead_path);
+		thp_set_read_ahead_path(finfo.dev_queue_read_ahead_path);
+	thp_save_settings();
 
 	success("OK");
 
@@ -798,7 +496,7 @@ static void __madvise_collapse(const char *msg, char *p, int nr_hpages,
 			       struct mem_ops *ops, bool expect)
 {
 	int ret;
-	struct settings settings = *current_settings();
+	struct thp_settings settings = *thp_current_settings();
 
 	printf("%s...", msg);
 
@@ -808,7 +506,7 @@ static void __madvise_collapse(const char *msg, char *p, int nr_hpages,
 	 */
 	settings.thp_enabled = THP_NEVER;
 	settings.shmem_enabled = SHMEM_NEVER;
-	push_settings(&settings);
+	thp_push_settings(&settings);
 
 	/* Clear VM_NOHUGEPAGE */
 	madvise(p, nr_hpages * hpage_pmd_size, MADV_HUGEPAGE);
@@ -820,7 +518,7 @@ static void __madvise_collapse(const char *msg, char *p, int nr_hpages,
 	else
 		success("OK");
 
-	pop_settings();
+	thp_pop_settings();
 }
 
 static void madvise_collapse(const char *msg, char *p, int nr_hpages,
@@ -850,13 +548,13 @@ static bool wait_for_scan(const char *msg, char *p, int nr_hpages,
 	madvise(p, nr_hpages * hpage_pmd_size, MADV_HUGEPAGE);
 
 	/* Wait until the second full_scan completed */
-	full_scans = read_num("khugepaged/full_scans") + 2;
+	full_scans = thp_read_num("khugepaged/full_scans") + 2;
 
 	printf("%s...", msg);
 	while (timeout--) {
 		if (ops->check_huge(p, nr_hpages))
 			break;
-		if (read_num("khugepaged/full_scans") >= full_scans)
+		if (thp_read_num("khugepaged/full_scans") >= full_scans)
 			break;
 		printf(".");
 		usleep(TICK);
@@ -911,11 +609,11 @@ static bool is_tmpfs(struct mem_ops *ops)
 
 static void alloc_at_fault(void)
 {
-	struct settings settings = *current_settings();
+	struct thp_settings settings = *thp_current_settings();
 	char *p;
 
 	settings.thp_enabled = THP_ALWAYS;
-	push_settings(&settings);
+	thp_push_settings(&settings);
 
 	p = alloc_mapping(1);
 	*p = 1;
@@ -925,7 +623,7 @@ static void alloc_at_fault(void)
 	else
 		fail("Fail");
 
-	pop_settings();
+	thp_pop_settings();
 
 	madvise(p, page_size, MADV_DONTNEED);
 	printf("Split huge PMD on MADV_DONTNEED...");
@@ -973,11 +671,11 @@ static void collapse_single_pte_entry(struct collapse_context *c, struct mem_ops
 static void collapse_max_ptes_none(struct collapse_context *c, struct mem_ops *ops)
 {
 	int max_ptes_none = hpage_pmd_nr / 2;
-	struct settings settings = *current_settings();
+	struct thp_settings settings = *thp_current_settings();
 	void *p;
 
 	settings.khugepaged.max_ptes_none = max_ptes_none;
-	push_settings(&settings);
+	thp_push_settings(&settings);
 
 	p = ops->setup_area(1);
 
@@ -1002,7 +700,7 @@ static void collapse_max_ptes_none(struct collapse_context *c, struct mem_ops *o
 	}
 skip:
 	ops->cleanup_area(p, hpage_pmd_size);
-	pop_settings();
+	thp_pop_settings();
 }
 
 static void collapse_swapin_single_pte(struct collapse_context *c, struct mem_ops *ops)
@@ -1033,7 +731,7 @@ static void collapse_swapin_single_pte(struct collapse_context *c, struct mem_op
 
 static void collapse_max_ptes_swap(struct collapse_context *c, struct mem_ops *ops)
 {
-	int max_ptes_swap = read_num("khugepaged/max_ptes_swap");
+	int max_ptes_swap = thp_read_num("khugepaged/max_ptes_swap");
 	void *p;
 
 	p = ops->setup_area(1);
@@ -1250,11 +948,11 @@ static void collapse_fork_compound(struct collapse_context *c, struct mem_ops *o
 			fail("Fail");
 		ops->fault(p, 0, page_size);
 
-		write_num("khugepaged/max_ptes_shared", hpage_pmd_nr - 1);
+		thp_write_num("khugepaged/max_ptes_shared", hpage_pmd_nr - 1);
 		c->collapse("Collapse PTE table full of compound pages in child",
 			    p, 1, ops, true);
-		write_num("khugepaged/max_ptes_shared",
-			  current_settings()->khugepaged.max_ptes_shared);
+		thp_write_num("khugepaged/max_ptes_shared",
+			  thp_current_settings()->khugepaged.max_ptes_shared);
 
 		validate_memory(p, 0, hpage_pmd_size);
 		ops->cleanup_area(p, hpage_pmd_size);
@@ -1275,7 +973,7 @@ static void collapse_fork_compound(struct collapse_context *c, struct mem_ops *o
 
 static void collapse_max_ptes_shared(struct collapse_context *c, struct mem_ops *ops)
 {
-	int max_ptes_shared = read_num("khugepaged/max_ptes_shared");
+	int max_ptes_shared = thp_read_num("khugepaged/max_ptes_shared");
 	int wstatus;
 	void *p;
 
@@ -1443,7 +1141,7 @@ static void parse_test_type(int argc, const char **argv)
 
 int main(int argc, const char **argv)
 {
-	struct settings default_settings = {
+	struct thp_settings default_settings = {
 		.thp_enabled = THP_MADVISE,
 		.thp_defrag = THP_DEFRAG_ALWAYS,
 		.shmem_enabled = SHMEM_ADVISE,
@@ -1484,7 +1182,7 @@ int main(int argc, const char **argv)
 	default_settings.khugepaged.pages_to_scan = hpage_pmd_nr * 8;
 
 	save_settings();
-	push_settings(&default_settings);
+	thp_push_settings(&default_settings);
 
 	alloc_at_fault();
 
diff --git a/tools/testing/selftests/mm/thp_settings.c b/tools/testing/selftests/mm/thp_settings.c
new file mode 100644
index 000000000000..5e8ec792cac7
--- /dev/null
+++ b/tools/testing/selftests/mm/thp_settings.c
@@ -0,0 +1,296 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <fcntl.h>
+#include <limits.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "thp_settings.h"
+
+#define THP_SYSFS "/sys/kernel/mm/transparent_hugepage/"
+#define MAX_SETTINGS_DEPTH 4
+static struct thp_settings settings_stack[MAX_SETTINGS_DEPTH];
+static int settings_index;
+static struct thp_settings saved_settings;
+static char dev_queue_read_ahead_path[PATH_MAX];
+
+static const char * const thp_enabled_strings[] = {
+	"always",
+	"madvise",
+	"never",
+	NULL
+};
+
+static const char * const thp_defrag_strings[] = {
+	"always",
+	"defer",
+	"defer+madvise",
+	"madvise",
+	"never",
+	NULL
+};
+
+static const char * const shmem_enabled_strings[] = {
+	"always",
+	"within_size",
+	"advise",
+	"never",
+	"deny",
+	"force",
+	NULL
+};
+
+int read_file(const char *path, char *buf, size_t buflen)
+{
+	int fd;
+	ssize_t numread;
+
+	fd = open(path, O_RDONLY);
+	if (fd == -1)
+		return 0;
+
+	numread = read(fd, buf, buflen - 1);
+	if (numread < 1) {
+		close(fd);
+		return 0;
+	}
+
+	buf[numread] = '\0';
+	close(fd);
+
+	return (unsigned int) numread;
+}
+
+int write_file(const char *path, const char *buf, size_t buflen)
+{
+	int fd;
+	ssize_t numwritten;
+
+	fd = open(path, O_WRONLY);
+	if (fd == -1) {
+		printf("open(%s)\n", path);
+		exit(EXIT_FAILURE);
+		return 0;
+	}
+
+	numwritten = write(fd, buf, buflen - 1);
+	close(fd);
+	if (numwritten < 1) {
+		printf("write(%s)\n", buf);
+		exit(EXIT_FAILURE);
+		return 0;
+	}
+
+	return (unsigned int) numwritten;
+}
+
+const unsigned long read_num(const char *path)
+{
+	char buf[21];
+
+	if (read_file(path, buf, sizeof(buf)) < 0) {
+		perror("read_file()");
+		exit(EXIT_FAILURE);
+	}
+
+	return strtoul(buf, NULL, 10);
+}
+
+void write_num(const char *path, unsigned long num)
+{
+	char buf[21];
+
+	sprintf(buf, "%ld", num);
+	if (!write_file(path, buf, strlen(buf) + 1)) {
+		perror(path);
+		exit(EXIT_FAILURE);
+	}
+}
+
+int thp_read_string(const char *name, const char * const strings[])
+{
+	char path[PATH_MAX];
+	char buf[256];
+	char *c;
+	int ret;
+
+	ret = snprintf(path, PATH_MAX, THP_SYSFS "%s", name);
+	if (ret >= PATH_MAX) {
+		printf("%s: Pathname is too long\n", __func__);
+		exit(EXIT_FAILURE);
+	}
+
+	if (!read_file(path, buf, sizeof(buf))) {
+		perror(path);
+		exit(EXIT_FAILURE);
+	}
+
+	c = strchr(buf, '[');
+	if (!c) {
+		printf("%s: Parse failure\n", __func__);
+		exit(EXIT_FAILURE);
+	}
+
+	c++;
+	memmove(buf, c, sizeof(buf) - (c - buf));
+
+	c = strchr(buf, ']');
+	if (!c) {
+		printf("%s: Parse failure\n", __func__);
+		exit(EXIT_FAILURE);
+	}
+	*c = '\0';
+
+	ret = 0;
+	while (strings[ret]) {
+		if (!strcmp(strings[ret], buf))
+			return ret;
+		ret++;
+	}
+
+	printf("Failed to parse %s\n", name);
+	exit(EXIT_FAILURE);
+}
+
+void thp_write_string(const char *name, const char *val)
+{
+	char path[PATH_MAX];
+	int ret;
+
+	ret = snprintf(path, PATH_MAX, THP_SYSFS "%s", name);
+	if (ret >= PATH_MAX) {
+		printf("%s: Pathname is too long\n", __func__);
+		exit(EXIT_FAILURE);
+	}
+
+	if (!write_file(path, val, strlen(val) + 1)) {
+		perror(path);
+		exit(EXIT_FAILURE);
+	}
+}
+
+const unsigned long thp_read_num(const char *name)
+{
+	char path[PATH_MAX];
+	int ret;
+
+	ret = snprintf(path, PATH_MAX, THP_SYSFS "%s", name);
+	if (ret >= PATH_MAX) {
+		printf("%s: Pathname is too long\n", __func__);
+		exit(EXIT_FAILURE);
+	}
+	return read_num(path);
+}
+
+void thp_write_num(const char *name, unsigned long num)
+{
+	char path[PATH_MAX];
+	int ret;
+
+	ret = snprintf(path, PATH_MAX, THP_SYSFS "%s", name);
+	if (ret >= PATH_MAX) {
+		printf("%s: Pathname is too long\n", __func__);
+		exit(EXIT_FAILURE);
+	}
+	write_num(path, num);
+}
+
+void thp_read_settings(struct thp_settings *settings)
+{
+	*settings = (struct thp_settings) {
+		.thp_enabled = thp_read_string("enabled", thp_enabled_strings),
+		.thp_defrag = thp_read_string("defrag", thp_defrag_strings),
+		.shmem_enabled =
+			thp_read_string("shmem_enabled", shmem_enabled_strings),
+		.use_zero_page = thp_read_num("use_zero_page"),
+	};
+	settings->khugepaged = (struct khugepaged_settings) {
+		.defrag = thp_read_num("khugepaged/defrag"),
+		.alloc_sleep_millisecs =
+			thp_read_num("khugepaged/alloc_sleep_millisecs"),
+		.scan_sleep_millisecs =
+			thp_read_num("khugepaged/scan_sleep_millisecs"),
+		.max_ptes_none = thp_read_num("khugepaged/max_ptes_none"),
+		.max_ptes_swap = thp_read_num("khugepaged/max_ptes_swap"),
+		.max_ptes_shared = thp_read_num("khugepaged/max_ptes_shared"),
+		.pages_to_scan = thp_read_num("khugepaged/pages_to_scan"),
+	};
+	if (dev_queue_read_ahead_path[0])
+		settings->read_ahead_kb = read_num(dev_queue_read_ahead_path);
+}
+
+void thp_write_settings(struct thp_settings *settings)
+{
+	struct khugepaged_settings *khugepaged = &settings->khugepaged;
+
+	thp_write_string("enabled", thp_enabled_strings[settings->thp_enabled]);
+	thp_write_string("defrag", thp_defrag_strings[settings->thp_defrag]);
+	thp_write_string("shmem_enabled",
+			shmem_enabled_strings[settings->shmem_enabled]);
+	thp_write_num("use_zero_page", settings->use_zero_page);
+
+	thp_write_num("khugepaged/defrag", khugepaged->defrag);
+	thp_write_num("khugepaged/alloc_sleep_millisecs",
+			khugepaged->alloc_sleep_millisecs);
+	thp_write_num("khugepaged/scan_sleep_millisecs",
+			khugepaged->scan_sleep_millisecs);
+	thp_write_num("khugepaged/max_ptes_none", khugepaged->max_ptes_none);
+	thp_write_num("khugepaged/max_ptes_swap", khugepaged->max_ptes_swap);
+	thp_write_num("khugepaged/max_ptes_shared", khugepaged->max_ptes_shared);
+	thp_write_num("khugepaged/pages_to_scan", khugepaged->pages_to_scan);
+
+	if (dev_queue_read_ahead_path[0])
+		write_num(dev_queue_read_ahead_path, settings->read_ahead_kb);
+}
+
+struct thp_settings *thp_current_settings(void)
+{
+	if (!settings_index) {
+		printf("Fail: No settings set");
+		exit(EXIT_FAILURE);
+	}
+	return settings_stack + settings_index - 1;
+}
+
+void thp_push_settings(struct thp_settings *settings)
+{
+	if (settings_index >= MAX_SETTINGS_DEPTH) {
+		printf("Fail: Settings stack exceeded");
+		exit(EXIT_FAILURE);
+	}
+	settings_stack[settings_index++] = *settings;
+	thp_write_settings(thp_current_settings());
+}
+
+void thp_pop_settings(void)
+{
+	if (settings_index <= 0) {
+		printf("Fail: Settings stack empty");
+		exit(EXIT_FAILURE);
+	}
+	--settings_index;
+	thp_write_settings(thp_current_settings());
+}
+
+void thp_restore_settings(void)
+{
+	thp_write_settings(&saved_settings);
+}
+
+void thp_save_settings(void)
+{
+	thp_read_settings(&saved_settings);
+}
+
+void thp_set_read_ahead_path(char *path)
+{
+	if (!path) {
+		dev_queue_read_ahead_path[0] = '\0';
+		return;
+	}
+
+	strncpy(dev_queue_read_ahead_path, path,
+		sizeof(dev_queue_read_ahead_path));
+	dev_queue_read_ahead_path[sizeof(dev_queue_read_ahead_path) - 1] = '\0';
+}
diff --git a/tools/testing/selftests/mm/thp_settings.h b/tools/testing/selftests/mm/thp_settings.h
new file mode 100644
index 000000000000..ff3d98c30617
--- /dev/null
+++ b/tools/testing/selftests/mm/thp_settings.h
@@ -0,0 +1,71 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __THP_SETTINGS_H__
+#define __THP_SETTINGS_H__
+
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+
+enum thp_enabled {
+	THP_ALWAYS,
+	THP_MADVISE,
+	THP_NEVER,
+};
+
+enum thp_defrag {
+	THP_DEFRAG_ALWAYS,
+	THP_DEFRAG_DEFER,
+	THP_DEFRAG_DEFER_MADVISE,
+	THP_DEFRAG_MADVISE,
+	THP_DEFRAG_NEVER,
+};
+
+enum shmem_enabled {
+	SHMEM_ALWAYS,
+	SHMEM_WITHIN_SIZE,
+	SHMEM_ADVISE,
+	SHMEM_NEVER,
+	SHMEM_DENY,
+	SHMEM_FORCE,
+};
+
+struct khugepaged_settings {
+	bool defrag;
+	unsigned int alloc_sleep_millisecs;
+	unsigned int scan_sleep_millisecs;
+	unsigned int max_ptes_none;
+	unsigned int max_ptes_swap;
+	unsigned int max_ptes_shared;
+	unsigned long pages_to_scan;
+};
+
+struct thp_settings {
+	enum thp_enabled thp_enabled;
+	enum thp_defrag thp_defrag;
+	enum shmem_enabled shmem_enabled;
+	bool use_zero_page;
+	struct khugepaged_settings khugepaged;
+	unsigned long read_ahead_kb;
+};
+
+int read_file(const char *path, char *buf, size_t buflen);
+int write_file(const char *path, const char *buf, size_t buflen);
+const unsigned long read_num(const char *path);
+void write_num(const char *path, unsigned long num);
+
+int thp_read_string(const char *name, const char * const strings[]);
+void thp_write_string(const char *name, const char *val);
+const unsigned long thp_read_num(const char *name);
+void thp_write_num(const char *name, unsigned long num);
+
+void thp_write_settings(struct thp_settings *settings);
+void thp_read_settings(struct thp_settings *settings);
+struct thp_settings *thp_current_settings(void);
+void thp_push_settings(struct thp_settings *settings);
+void thp_pop_settings(void);
+void thp_restore_settings(void);
+void thp_save_settings(void);
+
+void thp_set_read_ahead_path(char *path);
+
+#endif /* __THP_SETTINGS_H__ */
-- 
2.25.1

[PATCH v7 07/10] selftests/mm: Support small-sized THP interface in thp_settings

[Ryan Roberts]

Save and restore the new per-size hugepage enabled setting, if available
on the running kernel.

Since the number of per-size directories is not fixed, solve this as
simply as possible by catering for a maximum number in the thp_settings
struct (20). Each array index is the order. The value of THP_NEVER is
changed to 0 so that all of these new settings default to THP_NEVER and
the user only needs to fill in the ones they want to enable.

Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
---
 tools/testing/selftests/mm/khugepaged.c   |  3 ++
 tools/testing/selftests/mm/thp_settings.c | 55 ++++++++++++++++++++++-
 tools/testing/selftests/mm/thp_settings.h | 11 ++++-
 3 files changed, 67 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/mm/khugepaged.c b/tools/testing/selftests/mm/khugepaged.c
index b15e7fd70176..473ba095cffd 100644
--- a/tools/testing/selftests/mm/khugepaged.c
+++ b/tools/testing/selftests/mm/khugepaged.c
@@ -1141,6 +1141,7 @@ static void parse_test_type(int argc, const char **argv)
 
 int main(int argc, const char **argv)
 {
+	int hpage_pmd_order;
 	struct thp_settings default_settings = {
 		.thp_enabled = THP_MADVISE,
 		.thp_defrag = THP_DEFRAG_ALWAYS,
@@ -1175,11 +1176,13 @@ int main(int argc, const char **argv)
 		exit(EXIT_FAILURE);
 	}
 	hpage_pmd_nr = hpage_pmd_size / page_size;
+	hpage_pmd_order = __builtin_ctz(hpage_pmd_nr);
 
 	default_settings.khugepaged.max_ptes_none = hpage_pmd_nr - 1;
 	default_settings.khugepaged.max_ptes_swap = hpage_pmd_nr / 8;
 	default_settings.khugepaged.max_ptes_shared = hpage_pmd_nr / 2;
 	default_settings.khugepaged.pages_to_scan = hpage_pmd_nr * 8;
+	default_settings.hugepages[hpage_pmd_order].enabled = THP_GLOBAL;
 
 	save_settings();
 	thp_push_settings(&default_settings);
diff --git a/tools/testing/selftests/mm/thp_settings.c b/tools/testing/selftests/mm/thp_settings.c
index 5e8ec792cac7..3296995c8e4b 100644
--- a/tools/testing/selftests/mm/thp_settings.c
+++ b/tools/testing/selftests/mm/thp_settings.c
@@ -16,9 +16,10 @@ static struct thp_settings saved_settings;
 static char dev_queue_read_ahead_path[PATH_MAX];
 
 static const char * const thp_enabled_strings[] = {
+	"never",
 	"always",
+	"global",
 	"madvise",
-	"never",
 	NULL
 };
 
@@ -198,6 +199,10 @@ void thp_write_num(const char *name, unsigned long num)
 
 void thp_read_settings(struct thp_settings *settings)
 {
+	unsigned long orders = thp_supported_orders();
+	char path[PATH_MAX];
+	int i;
+
 	*settings = (struct thp_settings) {
 		.thp_enabled = thp_read_string("enabled", thp_enabled_strings),
 		.thp_defrag = thp_read_string("defrag", thp_defrag_strings),
@@ -218,11 +223,26 @@ void thp_read_settings(struct thp_settings *settings)
 	};
 	if (dev_queue_read_ahead_path[0])
 		settings->read_ahead_kb = read_num(dev_queue_read_ahead_path);
+
+	for (i = 0; i < NR_ORDERS; i++) {
+		if (!((1 << i) & orders)) {
+			settings->hugepages[i].enabled = THP_NEVER;
+			continue;
+		}
+		snprintf(path, PATH_MAX, "hugepages-%ukB/enabled",
+			(getpagesize() >> 10) << i);
+		settings->hugepages[i].enabled =
+			thp_read_string(path, thp_enabled_strings);
+	}
 }
 
 void thp_write_settings(struct thp_settings *settings)
 {
 	struct khugepaged_settings *khugepaged = &settings->khugepaged;
+	unsigned long orders = thp_supported_orders();
+	char path[PATH_MAX];
+	int enabled;
+	int i;
 
 	thp_write_string("enabled", thp_enabled_strings[settings->thp_enabled]);
 	thp_write_string("defrag", thp_defrag_strings[settings->thp_defrag]);
@@ -242,6 +262,15 @@ void thp_write_settings(struct thp_settings *settings)
 
 	if (dev_queue_read_ahead_path[0])
 		write_num(dev_queue_read_ahead_path, settings->read_ahead_kb);
+
+	for (i = 0; i < NR_ORDERS; i++) {
+		if (!((1 << i) & orders))
+			continue;
+		snprintf(path, PATH_MAX, "hugepages-%ukB/enabled",
+			(getpagesize() >> 10) << i);
+		enabled = settings->hugepages[i].enabled;
+		thp_write_string(path, thp_enabled_strings[enabled]);
+	}
 }
 
 struct thp_settings *thp_current_settings(void)
@@ -294,3 +323,27 @@ void thp_set_read_ahead_path(char *path)
 		sizeof(dev_queue_read_ahead_path));
 	dev_queue_read_ahead_path[sizeof(dev_queue_read_ahead_path) - 1] = '\0';
 }
+
+unsigned long thp_supported_orders(void)
+{
+	unsigned long orders = 0;
+	char path[PATH_MAX];
+	char buf[256];
+	int ret;
+	int i;
+
+	for (i = 0; i < NR_ORDERS; i++) {
+		ret = snprintf(path, PATH_MAX, THP_SYSFS "hugepages-%ukB/enabled",
+			(getpagesize() >> 10) << i);
+		if (ret >= PATH_MAX) {
+			printf("%s: Pathname is too long\n", __func__);
+			exit(EXIT_FAILURE);
+		}
+
+		ret = read_file(path, buf, sizeof(buf));
+		if (ret)
+			orders |= 1UL << i;
+	}
+
+	return orders;
+}
diff --git a/tools/testing/selftests/mm/thp_settings.h b/tools/testing/selftests/mm/thp_settings.h
index ff3d98c30617..8e71e323546c 100644
--- a/tools/testing/selftests/mm/thp_settings.h
+++ b/tools/testing/selftests/mm/thp_settings.h
@@ -7,9 +7,10 @@
 #include <stdint.h>
 
 enum thp_enabled {
+	THP_NEVER,
 	THP_ALWAYS,
+	THP_GLOBAL,
 	THP_MADVISE,
-	THP_NEVER,
 };
 
 enum thp_defrag {
@@ -29,6 +30,12 @@ enum shmem_enabled {
 	SHMEM_FORCE,
 };
 
+#define NR_ORDERS 20
+
+struct hugepages_settings {
+	enum thp_enabled enabled;
+};
+
 struct khugepaged_settings {
 	bool defrag;
 	unsigned int alloc_sleep_millisecs;
@@ -46,6 +53,7 @@ struct thp_settings {
 	bool use_zero_page;
 	struct khugepaged_settings khugepaged;
 	unsigned long read_ahead_kb;
+	struct hugepages_settings hugepages[NR_ORDERS];
 };
 
 int read_file(const char *path, char *buf, size_t buflen);
@@ -67,5 +75,6 @@ void thp_restore_settings(void);
 void thp_save_settings(void);
 
 void thp_set_read_ahead_path(char *path);
+unsigned long thp_supported_orders(void);
 
 #endif /* __THP_SETTINGS_H__ */
-- 
2.25.1

[PATCH v7 08/10] selftests/mm/khugepaged: Enlighten for small-sized THP

[Ryan Roberts]

The `collapse_max_ptes_none` test was previously failing when
small-sized THP had enabled="always". The root cause is because the test
faults in 1 page less than the threshold it set for collapsing. But when
using small-sized THP we "over allocate" and therefore the threshold is
passed, and collapse unexpectedly succeeds.

Solve this by enlightening khugepaged selftest. Add a command line
option to pass in the desired small-sized THP that should be used for
all anonymous allocations. The harness will then explicitly configure
small-sized THP as requested and modify the `collapse_max_ptes_none`
test so that it faults in the threshold minus the number of pages in the
configured small-sized THP. If no command line option is provided,
default to order 0, as per previous behaviour.

I chose to use an order in the command line interface, since this makes
the interface agnostic of base page size, making it easier to invoke
from run_vmtests.sh.

Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
---
 tools/testing/selftests/mm/khugepaged.c   | 48 +++++++++++++++++------
 tools/testing/selftests/mm/run_vmtests.sh |  2 +
 2 files changed, 39 insertions(+), 11 deletions(-)

diff --git a/tools/testing/selftests/mm/khugepaged.c b/tools/testing/selftests/mm/khugepaged.c
index 473ba095cffd..4d24f2eb158e 100644
--- a/tools/testing/selftests/mm/khugepaged.c
+++ b/tools/testing/selftests/mm/khugepaged.c
@@ -28,6 +28,7 @@
 static unsigned long hpage_pmd_size;
 static unsigned long page_size;
 static int hpage_pmd_nr;
+static int anon_order;
 
 #define PID_SMAPS "/proc/self/smaps"
 #define TEST_FILE "collapse_test_file"
@@ -607,6 +608,11 @@ static bool is_tmpfs(struct mem_ops *ops)
 	return ops == &__file_ops && finfo.type == VMA_SHMEM;
 }
 
+static bool is_anon(struct mem_ops *ops)
+{
+	return ops == &__anon_ops;
+}
+
 static void alloc_at_fault(void)
 {
 	struct thp_settings settings = *thp_current_settings();
@@ -673,6 +679,7 @@ static void collapse_max_ptes_none(struct collapse_context *c, struct mem_ops *o
 	int max_ptes_none = hpage_pmd_nr / 2;
 	struct thp_settings settings = *thp_current_settings();
 	void *p;
+	int fault_nr_pages = is_anon(ops) ? 1 << anon_order : 1;
 
 	settings.khugepaged.max_ptes_none = max_ptes_none;
 	thp_push_settings(&settings);
@@ -686,10 +693,10 @@ static void collapse_max_ptes_none(struct collapse_context *c, struct mem_ops *o
 		goto skip;
 	}
 
-	ops->fault(p, 0, (hpage_pmd_nr - max_ptes_none - 1) * page_size);
+	ops->fault(p, 0, (hpage_pmd_nr - max_ptes_none - fault_nr_pages) * page_size);
 	c->collapse("Maybe collapse with max_ptes_none exceeded", p, 1,
 		    ops, !c->enforce_pte_scan_limits);
-	validate_memory(p, 0, (hpage_pmd_nr - max_ptes_none - 1) * page_size);
+	validate_memory(p, 0, (hpage_pmd_nr - max_ptes_none - fault_nr_pages) * page_size);
 
 	if (c->enforce_pte_scan_limits) {
 		ops->fault(p, 0, (hpage_pmd_nr - max_ptes_none) * page_size);
@@ -1076,7 +1083,7 @@ static void madvise_retracted_page_tables(struct collapse_context *c,
 
 static void usage(void)
 {
-	fprintf(stderr, "\nUsage: ./khugepaged <test type> [dir]\n\n");
+	fprintf(stderr, "\nUsage: ./khugepaged [OPTIONS] <test type> [dir]\n\n");
 	fprintf(stderr, "\t<test type>\t: <context>:<mem_type>\n");
 	fprintf(stderr, "\t<context>\t: [all|khugepaged|madvise]\n");
 	fprintf(stderr, "\t<mem_type>\t: [all|anon|file|shmem]\n");
@@ -1085,15 +1092,34 @@ static void usage(void)
 	fprintf(stderr,	"\tCONFIG_READ_ONLY_THP_FOR_FS=y\n");
 	fprintf(stderr, "\n\tif [dir] is a (sub)directory of a tmpfs mount, tmpfs must be\n");
 	fprintf(stderr,	"\tmounted with huge=madvise option for khugepaged tests to work\n");
+	fprintf(stderr,	"\n\tSupported Options:\n");
+	fprintf(stderr,	"\t\t-h: This help message.\n");
+	fprintf(stderr,	"\t\t-s: Small-sized THP size, expressed as page order.\n");
+	fprintf(stderr,	"\t\t    Defaults to 0. Use this size for anon allocations.\n");
 	exit(1);
 }
 
-static void parse_test_type(int argc, const char **argv)
+static void parse_test_type(int argc, char **argv)
 {
+	int opt;
 	char *buf;
 	const char *token;
 
-	if (argc == 1) {
+	while ((opt = getopt(argc, argv, "s:h")) != -1) {
+		switch (opt) {
+		case 's':
+			anon_order = atoi(optarg);
+			break;
+		case 'h':
+		default:
+			usage();
+		}
+	}
+
+	argv += optind;
+	argc -= optind;
+
+	if (argc == 0) {
 		/* Backwards compatibility */
 		khugepaged_context =  &__khugepaged_context;
 		madvise_context =  &__madvise_context;
@@ -1101,7 +1127,7 @@ static void parse_test_type(int argc, const char **argv)
 		return;
 	}
 
-	buf = strdup(argv[1]);
+	buf = strdup(argv[0]);
 	token = strsep(&buf, ":");
 
 	if (!strcmp(token, "all")) {
@@ -1135,11 +1161,13 @@ static void parse_test_type(int argc, const char **argv)
 	if (!file_ops)
 		return;
 
-	if (argc != 3)
+	if (argc != 2)
 		usage();
+
+	get_finfo(argv[1]);
 }
 
-int main(int argc, const char **argv)
+int main(int argc, char **argv)
 {
 	int hpage_pmd_order;
 	struct thp_settings default_settings = {
@@ -1164,9 +1192,6 @@ int main(int argc, const char **argv)
 
 	parse_test_type(argc, argv);
 
-	if (file_ops)
-		get_finfo(argv[2]);
-
 	setbuf(stdout, NULL);
 
 	page_size = getpagesize();
@@ -1183,6 +1208,7 @@ int main(int argc, const char **argv)
 	default_settings.khugepaged.max_ptes_shared = hpage_pmd_nr / 2;
 	default_settings.khugepaged.pages_to_scan = hpage_pmd_nr * 8;
 	default_settings.hugepages[hpage_pmd_order].enabled = THP_GLOBAL;
+	default_settings.hugepages[anon_order].enabled = THP_ALWAYS;
 
 	save_settings();
 	thp_push_settings(&default_settings);
diff --git a/tools/testing/selftests/mm/run_vmtests.sh b/tools/testing/selftests/mm/run_vmtests.sh
index 00757445278e..f3fa2238daef 100755
--- a/tools/testing/selftests/mm/run_vmtests.sh
+++ b/tools/testing/selftests/mm/run_vmtests.sh
@@ -359,6 +359,8 @@ CATEGORY="cow" run_test ./cow
 
 CATEGORY="thp" run_test ./khugepaged
 
+CATEGORY="thp" run_test ./khugepaged -s 2
+
 CATEGORY="thp" run_test ./transhuge-stress -d 20
 
 CATEGORY="thp" run_test ./split_huge_page_test
-- 
2.25.1

[PATCH v7 09/10] selftests/mm/cow: Generalize do_run_with_thp() helper

[Ryan Roberts]

do_run_with_thp() prepares (PMD-sized) THP memory into different states
before running tests. With the introduction of small-sized THP, we would
like to reuse this logic to also test those smaller THP sizes. So let's
add a size parameter which tells the function what size THP it should
operate on.

A separate commit will utilize this change to add new tests for
small-sized THP, where available.

Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
---
 tools/testing/selftests/mm/cow.c | 146 +++++++++++++++++--------------
 1 file changed, 79 insertions(+), 67 deletions(-)

diff --git a/tools/testing/selftests/mm/cow.c b/tools/testing/selftests/mm/cow.c
index 7324ce5363c0..d03c453cfd5c 100644
--- a/tools/testing/selftests/mm/cow.c
+++ b/tools/testing/selftests/mm/cow.c
@@ -32,7 +32,7 @@
 
 static size_t pagesize;
 static int pagemap_fd;
-static size_t thpsize;
+static size_t pmdsize;
 static int nr_hugetlbsizes;
 static size_t hugetlbsizes[10];
 static int gup_fd;
@@ -734,14 +734,14 @@ enum thp_run {
 	THP_RUN_PARTIAL_SHARED,
 };
 
-static void do_run_with_thp(test_fn fn, enum thp_run thp_run)
+static void do_run_with_thp(test_fn fn, enum thp_run thp_run, size_t size)
 {
 	char *mem, *mmap_mem, *tmp, *mremap_mem = MAP_FAILED;
-	size_t size, mmap_size, mremap_size;
+	size_t mmap_size, mremap_size;
 	int ret;
 
-	/* For alignment purposes, we need twice the thp size. */
-	mmap_size = 2 * thpsize;
+	/* For alignment purposes, we need twice the requested size. */
+	mmap_size = 2 * size;
 	mmap_mem = mmap(NULL, mmap_size, PROT_READ | PROT_WRITE,
 			MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
 	if (mmap_mem == MAP_FAILED) {
@@ -749,36 +749,40 @@ static void do_run_with_thp(test_fn fn, enum thp_run thp_run)
 		return;
 	}
 
-	/* We need a THP-aligned memory area. */
-	mem = (char *)(((uintptr_t)mmap_mem + thpsize) & ~(thpsize - 1));
+	/* We need to naturally align the memory area. */
+	mem = (char *)(((uintptr_t)mmap_mem + size) & ~(size - 1));
 
-	ret = madvise(mem, thpsize, MADV_HUGEPAGE);
+	ret = madvise(mem, size, MADV_HUGEPAGE);
 	if (ret) {
 		ksft_test_result_fail("MADV_HUGEPAGE failed\n");
 		goto munmap;
 	}
 
 	/*
-	 * Try to populate a THP. Touch the first sub-page and test if we get
-	 * another sub-page populated automatically.
+	 * Try to populate a THP. Touch the first sub-page and test if
+	 * we get the last sub-page populated automatically.
 	 */
 	mem[0] = 0;
-	if (!pagemap_is_populated(pagemap_fd, mem + pagesize)) {
+	if (!pagemap_is_populated(pagemap_fd, mem + size - pagesize)) {
 		ksft_test_result_skip("Did not get a THP populated\n");
 		goto munmap;
 	}
-	memset(mem, 0, thpsize);
+	memset(mem, 0, size);
 
-	size = thpsize;
 	switch (thp_run) {
 	case THP_RUN_PMD:
 	case THP_RUN_PMD_SWAPOUT:
+		if (size != pmdsize) {
+			ksft_test_result_fail("test bug: can't PMD-map size\n");
+			goto munmap;
+		}
 		break;
 	case THP_RUN_PTE:
 	case THP_RUN_PTE_SWAPOUT:
 		/*
 		 * Trigger PTE-mapping the THP by temporarily mapping a single
-		 * subpage R/O.
+		 * subpage R/O. This is a noop if the THP is not pmdsize (and
+		 * therefore already PTE-mapped).
 		 */
 		ret = mprotect(mem + pagesize, pagesize, PROT_READ);
 		if (ret) {
@@ -797,7 +801,7 @@ static void do_run_with_thp(test_fn fn, enum thp_run thp_run)
 		 * Discard all but a single subpage of that PTE-mapped THP. What
 		 * remains is a single PTE mapping a single subpage.
 		 */
-		ret = madvise(mem + pagesize, thpsize - pagesize, MADV_DONTNEED);
+		ret = madvise(mem + pagesize, size - pagesize, MADV_DONTNEED);
 		if (ret) {
 			ksft_test_result_fail("MADV_DONTNEED failed\n");
 			goto munmap;
@@ -809,7 +813,7 @@ static void do_run_with_thp(test_fn fn, enum thp_run thp_run)
 		 * Remap half of the THP. We need some new memory location
 		 * for that.
 		 */
-		mremap_size = thpsize / 2;
+		mremap_size = size / 2;
 		mremap_mem = mmap(NULL, mremap_size, PROT_NONE,
 				  MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
 		if (mem == MAP_FAILED) {
@@ -830,7 +834,7 @@ static void do_run_with_thp(test_fn fn, enum thp_run thp_run)
 		 * child. This will result in some parts of the THP never
 		 * have been shared.
 		 */
-		ret = madvise(mem + pagesize, thpsize - pagesize, MADV_DONTFORK);
+		ret = madvise(mem + pagesize, size - pagesize, MADV_DONTFORK);
 		if (ret) {
 			ksft_test_result_fail("MADV_DONTFORK failed\n");
 			goto munmap;
@@ -844,7 +848,7 @@ static void do_run_with_thp(test_fn fn, enum thp_run thp_run)
 		}
 		wait(&ret);
 		/* Allow for sharing all pages again. */
-		ret = madvise(mem + pagesize, thpsize - pagesize, MADV_DOFORK);
+		ret = madvise(mem + pagesize, size - pagesize, MADV_DOFORK);
 		if (ret) {
 			ksft_test_result_fail("MADV_DOFORK failed\n");
 			goto munmap;
@@ -875,52 +879,60 @@ static void do_run_with_thp(test_fn fn, enum thp_run thp_run)
 		munmap(mremap_mem, mremap_size);
 }
 
-static void run_with_thp(test_fn fn, const char *desc)
+static void run_with_thp(test_fn fn, const char *desc, size_t size)
 {
-	ksft_print_msg("[RUN] %s ... with THP\n", desc);
-	do_run_with_thp(fn, THP_RUN_PMD);
+	ksft_print_msg("[RUN] %s ... with THP (%zu kB)\n",
+		desc, size / 1024);
+	do_run_with_thp(fn, THP_RUN_PMD, size);
 }
 
-static void run_with_thp_swap(test_fn fn, const char *desc)
+static void run_with_thp_swap(test_fn fn, const char *desc, size_t size)
 {
-	ksft_print_msg("[RUN] %s ... with swapped-out THP\n", desc);
-	do_run_with_thp(fn, THP_RUN_PMD_SWAPOUT);
+	ksft_print_msg("[RUN] %s ... with swapped-out THP (%zu kB)\n",
+		desc, size / 1024);
+	do_run_with_thp(fn, THP_RUN_PMD_SWAPOUT, size);
 }
 
-static void run_with_pte_mapped_thp(test_fn fn, const char *desc)
+static void run_with_pte_mapped_thp(test_fn fn, const char *desc, size_t size)
 {
-	ksft_print_msg("[RUN] %s ... with PTE-mapped THP\n", desc);
-	do_run_with_thp(fn, THP_RUN_PTE);
+	ksft_print_msg("[RUN] %s ... with PTE-mapped THP (%zu kB)\n",
+		desc, size / 1024);
+	do_run_with_thp(fn, THP_RUN_PTE, size);
 }
 
-static void run_with_pte_mapped_thp_swap(test_fn fn, const char *desc)
+static void run_with_pte_mapped_thp_swap(test_fn fn, const char *desc, size_t size)
 {
-	ksft_print_msg("[RUN] %s ... with swapped-out, PTE-mapped THP\n", desc);
-	do_run_with_thp(fn, THP_RUN_PTE_SWAPOUT);
+	ksft_print_msg("[RUN] %s ... with swapped-out, PTE-mapped THP (%zu kB)\n",
+		desc, size / 1024);
+	do_run_with_thp(fn, THP_RUN_PTE_SWAPOUT, size);
 }
 
-static void run_with_single_pte_of_thp(test_fn fn, const char *desc)
+static void run_with_single_pte_of_thp(test_fn fn, const char *desc, size_t size)
 {
-	ksft_print_msg("[RUN] %s ... with single PTE of THP\n", desc);
-	do_run_with_thp(fn, THP_RUN_SINGLE_PTE);
+	ksft_print_msg("[RUN] %s ... with single PTE of THP (%zu kB)\n",
+		desc, size / 1024);
+	do_run_with_thp(fn, THP_RUN_SINGLE_PTE, size);
 }
 
-static void run_with_single_pte_of_thp_swap(test_fn fn, const char *desc)
+static void run_with_single_pte_of_thp_swap(test_fn fn, const char *desc, size_t size)
 {
-	ksft_print_msg("[RUN] %s ... with single PTE of swapped-out THP\n", desc);
-	do_run_with_thp(fn, THP_RUN_SINGLE_PTE_SWAPOUT);
+	ksft_print_msg("[RUN] %s ... with single PTE of swapped-out THP (%zu kB)\n",
+		desc, size / 1024);
+	do_run_with_thp(fn, THP_RUN_SINGLE_PTE_SWAPOUT, size);
 }
 
-static void run_with_partial_mremap_thp(test_fn fn, const char *desc)
+static void run_with_partial_mremap_thp(test_fn fn, const char *desc, size_t size)
 {
-	ksft_print_msg("[RUN] %s ... with partially mremap()'ed THP\n", desc);
-	do_run_with_thp(fn, THP_RUN_PARTIAL_MREMAP);
+	ksft_print_msg("[RUN] %s ... with partially mremap()'ed THP (%zu kB)\n",
+		desc, size / 1024);
+	do_run_with_thp(fn, THP_RUN_PARTIAL_MREMAP, size);
 }
 
-static void run_with_partial_shared_thp(test_fn fn, const char *desc)
+static void run_with_partial_shared_thp(test_fn fn, const char *desc, size_t size)
 {
-	ksft_print_msg("[RUN] %s ... with partially shared THP\n", desc);
-	do_run_with_thp(fn, THP_RUN_PARTIAL_SHARED);
+	ksft_print_msg("[RUN] %s ... with partially shared THP (%zu kB)\n",
+		desc, size / 1024);
+	do_run_with_thp(fn, THP_RUN_PARTIAL_SHARED, size);
 }
 
 static void run_with_hugetlb(test_fn fn, const char *desc, size_t hugetlbsize)
@@ -1091,15 +1103,15 @@ static void run_anon_test_case(struct test_case const *test_case)
 
 	run_with_base_page(test_case->fn, test_case->desc);
 	run_with_base_page_swap(test_case->fn, test_case->desc);
-	if (thpsize) {
-		run_with_thp(test_case->fn, test_case->desc);
-		run_with_thp_swap(test_case->fn, test_case->desc);
-		run_with_pte_mapped_thp(test_case->fn, test_case->desc);
-		run_with_pte_mapped_thp_swap(test_case->fn, test_case->desc);
-		run_with_single_pte_of_thp(test_case->fn, test_case->desc);
-		run_with_single_pte_of_thp_swap(test_case->fn, test_case->desc);
-		run_with_partial_mremap_thp(test_case->fn, test_case->desc);
-		run_with_partial_shared_thp(test_case->fn, test_case->desc);
+	if (pmdsize) {
+		run_with_thp(test_case->fn, test_case->desc, pmdsize);
+		run_with_thp_swap(test_case->fn, test_case->desc, pmdsize);
+		run_with_pte_mapped_thp(test_case->fn, test_case->desc, pmdsize);
+		run_with_pte_mapped_thp_swap(test_case->fn, test_case->desc, pmdsize);
+		run_with_single_pte_of_thp(test_case->fn, test_case->desc, pmdsize);
+		run_with_single_pte_of_thp_swap(test_case->fn, test_case->desc, pmdsize);
+		run_with_partial_mremap_thp(test_case->fn, test_case->desc, pmdsize);
+		run_with_partial_shared_thp(test_case->fn, test_case->desc, pmdsize);
 	}
 	for (i = 0; i < nr_hugetlbsizes; i++)
 		run_with_hugetlb(test_case->fn, test_case->desc,
@@ -1120,7 +1132,7 @@ static int tests_per_anon_test_case(void)
 {
 	int tests = 2 + nr_hugetlbsizes;
 
-	if (thpsize)
+	if (pmdsize)
 		tests += 8;
 	return tests;
 }
@@ -1329,7 +1341,7 @@ static void run_anon_thp_test_cases(void)
 {
 	int i;
 
-	if (!thpsize)
+	if (!pmdsize)
 		return;
 
 	ksft_print_msg("[INFO] Anonymous THP tests\n");
@@ -1338,13 +1350,13 @@ static void run_anon_thp_test_cases(void)
 		struct test_case const *test_case = &anon_thp_test_cases[i];
 
 		ksft_print_msg("[RUN] %s\n", test_case->desc);
-		do_run_with_thp(test_case->fn, THP_RUN_PMD);
+		do_run_with_thp(test_case->fn, THP_RUN_PMD, pmdsize);
 	}
 }
 
 static int tests_per_anon_thp_test_case(void)
 {
-	return thpsize ? 1 : 0;
+	return pmdsize ? 1 : 0;
 }
 
 typedef void (*non_anon_test_fn)(char *mem, const char *smem, size_t size);
@@ -1419,7 +1431,7 @@ static void run_with_huge_zeropage(non_anon_test_fn fn, const char *desc)
 	}
 
 	/* For alignment purposes, we need twice the thp size. */
-	mmap_size = 2 * thpsize;
+	mmap_size = 2 * pmdsize;
 	mmap_mem = mmap(NULL, mmap_size, PROT_READ | PROT_WRITE,
 			MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
 	if (mmap_mem == MAP_FAILED) {
@@ -1434,11 +1446,11 @@ static void run_with_huge_zeropage(non_anon_test_fn fn, const char *desc)
 	}
 
 	/* We need a THP-aligned memory area. */
-	mem = (char *)(((uintptr_t)mmap_mem + thpsize) & ~(thpsize - 1));
-	smem = (char *)(((uintptr_t)mmap_smem + thpsize) & ~(thpsize - 1));
+	mem = (char *)(((uintptr_t)mmap_mem + pmdsize) & ~(pmdsize - 1));
+	smem = (char *)(((uintptr_t)mmap_smem + pmdsize) & ~(pmdsize - 1));
 
-	ret = madvise(mem, thpsize, MADV_HUGEPAGE);
-	ret |= madvise(smem, thpsize, MADV_HUGEPAGE);
+	ret = madvise(mem, pmdsize, MADV_HUGEPAGE);
+	ret |= madvise(smem, pmdsize, MADV_HUGEPAGE);
 	if (ret) {
 		ksft_test_result_fail("MADV_HUGEPAGE failed\n");
 		goto munmap;
@@ -1457,7 +1469,7 @@ static void run_with_huge_zeropage(non_anon_test_fn fn, const char *desc)
 		goto munmap;
 	}
 
-	fn(mem, smem, thpsize);
+	fn(mem, smem, pmdsize);
 munmap:
 	munmap(mmap_mem, mmap_size);
 	if (mmap_smem != MAP_FAILED)
@@ -1650,7 +1662,7 @@ static void run_non_anon_test_case(struct non_anon_test_case const *test_case)
 	run_with_zeropage(test_case->fn, test_case->desc);
 	run_with_memfd(test_case->fn, test_case->desc);
 	run_with_tmpfile(test_case->fn, test_case->desc);
-	if (thpsize)
+	if (pmdsize)
 		run_with_huge_zeropage(test_case->fn, test_case->desc);
 	for (i = 0; i < nr_hugetlbsizes; i++)
 		run_with_memfd_hugetlb(test_case->fn, test_case->desc,
@@ -1671,7 +1683,7 @@ static int tests_per_non_anon_test_case(void)
 {
 	int tests = 3 + nr_hugetlbsizes;
 
-	if (thpsize)
+	if (pmdsize)
 		tests += 1;
 	return tests;
 }
@@ -1681,10 +1693,10 @@ int main(int argc, char **argv)
 	int err;
 
 	pagesize = getpagesize();
-	thpsize = read_pmd_pagesize();
-	if (thpsize)
-		ksft_print_msg("[INFO] detected THP size: %zu KiB\n",
-			       thpsize / 1024);
+	pmdsize = read_pmd_pagesize();
+	if (pmdsize)
+		ksft_print_msg("[INFO] detected PMD-mapped THP size: %zu KiB\n",
+			       pmdsize / 1024);
 	nr_hugetlbsizes = detect_hugetlb_page_sizes(hugetlbsizes,
 						    ARRAY_SIZE(hugetlbsizes));
 	detect_huge_zeropage();
-- 
2.25.1

[PATCH v7 10/10] selftests/mm/cow: Add tests for anonymous small-sized THP

[Ryan Roberts]

Add tests similar to the existing PMD-sized THP tests, but which operate
on memory backed by (PTE-mapped) small-sized THP. This reuses all the
existing infrastructure. If the test suite detects that small-sized THP
is not supported by the kernel, the new tests are skipped.

Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
---
 tools/testing/selftests/mm/cow.c | 71 +++++++++++++++++++++++++++++++-
 1 file changed, 70 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/mm/cow.c b/tools/testing/selftests/mm/cow.c
index d03c453cfd5c..3efc395c7077 100644
--- a/tools/testing/selftests/mm/cow.c
+++ b/tools/testing/selftests/mm/cow.c
@@ -29,15 +29,49 @@
 #include "../../../../mm/gup_test.h"
 #include "../kselftest.h"
 #include "vm_util.h"
+#include "thp_settings.h"
 
 static size_t pagesize;
 static int pagemap_fd;
 static size_t pmdsize;
+static int nr_thpsmallsizes;
+static size_t thpsmallsizes[20];
 static int nr_hugetlbsizes;
 static size_t hugetlbsizes[10];
 static int gup_fd;
 static bool has_huge_zeropage;
 
+static int sz2ord(size_t size)
+{
+	return __builtin_ctzll(size / pagesize);
+}
+
+static int detect_smallthp_sizes(size_t sizes[], int max)
+{
+	int count = 0;
+	unsigned long orders;
+	size_t kb;
+	int i;
+
+	/* thp not supported at all. */
+	if (!pmdsize)
+		return 0;
+
+	orders = thp_supported_orders();
+
+	/* Only interested in small-sized THP (less than PMD-size). */
+	for (i = 0; i < sz2ord(pmdsize); i++) {
+		if (!(orders & (1UL << i)))
+			continue;
+		kb = (pagesize >> 10) << i;
+		sizes[count++] = kb * 1024;
+		ksft_print_msg("[INFO] detected small-sized THP size: %zu KiB\n",
+			       kb);
+	}
+
+	return count;
+}
+
 static void detect_huge_zeropage(void)
 {
 	int fd = open("/sys/kernel/mm/transparent_hugepage/use_zero_page",
@@ -1113,6 +1147,23 @@ static void run_anon_test_case(struct test_case const *test_case)
 		run_with_partial_mremap_thp(test_case->fn, test_case->desc, pmdsize);
 		run_with_partial_shared_thp(test_case->fn, test_case->desc, pmdsize);
 	}
+	for (i = 0; i < nr_thpsmallsizes; i++) {
+		size_t size = thpsmallsizes[i];
+		struct thp_settings settings = *thp_current_settings();
+
+		settings.hugepages[sz2ord(pmdsize)].enabled = THP_NEVER;
+		settings.hugepages[sz2ord(size)].enabled = THP_ALWAYS;
+		thp_push_settings(&settings);
+
+		run_with_pte_mapped_thp(test_case->fn, test_case->desc, size);
+		run_with_pte_mapped_thp_swap(test_case->fn, test_case->desc, size);
+		run_with_single_pte_of_thp(test_case->fn, test_case->desc, size);
+		run_with_single_pte_of_thp_swap(test_case->fn, test_case->desc, size);
+		run_with_partial_mremap_thp(test_case->fn, test_case->desc, size);
+		run_with_partial_shared_thp(test_case->fn, test_case->desc, size);
+
+		thp_pop_settings();
+	}
 	for (i = 0; i < nr_hugetlbsizes; i++)
 		run_with_hugetlb(test_case->fn, test_case->desc,
 				 hugetlbsizes[i]);
@@ -1134,6 +1185,7 @@ static int tests_per_anon_test_case(void)
 
 	if (pmdsize)
 		tests += 8;
+	tests += 6 * nr_thpsmallsizes;
 	return tests;
 }
 
@@ -1691,12 +1743,24 @@ static int tests_per_non_anon_test_case(void)
 int main(int argc, char **argv)
 {
 	int err;
+	struct thp_settings default_settings;
 
 	pagesize = getpagesize();
 	pmdsize = read_pmd_pagesize();
-	if (pmdsize)
+	if (pmdsize) {
+		/* Only if THP is supported. */
+		thp_read_settings(&default_settings);
+		default_settings.hugepages[sz2ord(pmdsize)].enabled = THP_GLOBAL;
+		thp_save_settings();
+		thp_push_settings(&default_settings);
+
 		ksft_print_msg("[INFO] detected PMD-mapped THP size: %zu KiB\n",
 			       pmdsize / 1024);
+
+		nr_thpsmallsizes = detect_smallthp_sizes(thpsmallsizes,
+						    ARRAY_SIZE(thpsmallsizes));
+	}
+
 	nr_hugetlbsizes = detect_hugetlb_page_sizes(hugetlbsizes,
 						    ARRAY_SIZE(hugetlbsizes));
 	detect_huge_zeropage();
@@ -1715,6 +1779,11 @@ int main(int argc, char **argv)
 	run_anon_thp_test_cases();
 	run_non_anon_test_cases();
 
+	if (pmdsize) {
+		/* Only if THP is supported. */
+		thp_restore_settings();
+	}
+
 	err = ksft_get_fail_cnt();
 	if (err)
 		ksft_exit_fail_msg("%d out of %d tests failed\n",
-- 
2.25.1