[PATCH v2 00/16] A few cleanup patches for mm

[PATCH v2 00/16] A few cleanup patches for mm

[Miaohe Lin]

Hi everyone,
This series contains a few cleanup patches to remove the obsolete
comments and functions, use helper macro to improve readability and
so on. More details can be found in the respective changelogs.
Thanks!
---
v2:
  Thanks David, Oscar, Anshuman and Matthew for review and comment!
  Collect Reviewed-by and Acked-by tag.
  3/6: Further remove NR_PCP_ORDER_WIDTH per Matthew.
  8/16: Tweak changelog to better explain the issue per Oscar.
  12/16: Adjust if block to match comment per David.
---
Miaohe Lin (16):
  mm/page_alloc: ensure kswapd doesn't accidentally go to sleep
  mm/page_alloc: make zone_pcp_update() static
  mm: remove obsolete macro NR_PCP_ORDER_MASK and NR_PCP_ORDER_WIDTH
  mm/page_alloc: remove obsolete comment in zone_statistics()
  mm/page_alloc: add __init annotations to
    init_mem_debugging_and_hardening()
  mm/page_alloc: fix freeing static percpu memory
  mm: remove obsolete pgdat_is_empty()
  mm/page_alloc: add missing is_migrate_isolate() check in
    set_page_guard()
  mm/page_alloc: use local variable zone_idx directly
  mm, memory_hotplug: remove obsolete generic_free_nodedata()
  mm/page_alloc: make boot_nodestats static
  mm/page_alloc: use helper macro SZ_1{K,M}
  mm/page_alloc: init local variable buddy_pfn
  mm/page_alloc: use costly_order in WARN_ON_ONCE_GFP()
  mm/page_alloc: remove obsolete gfpflags_normal_context()
  mm/page_alloc: fix obsolete comment in deferred_pfn_valid()

 include/linux/gfp.h            | 23 -------------
 include/linux/memory_hotplug.h |  8 -----
 include/linux/mm.h             |  2 +-
 include/linux/mmzone.h         | 12 -------
 mm/internal.h                  |  3 --
 mm/page_alloc.c                | 63 ++++++++++++++++------------------
 6 files changed, 31 insertions(+), 80 deletions(-)

-- 
2.23.0

[PATCH v2 01/16] mm/page_alloc: ensure kswapd doesn't accidentally go to sleep

[Miaohe Lin]

If ALLOC_KSWAPD is set, wake_all_kswapds() will be called to ensure
kswapd doesn't accidentally go to sleep. But when reserve_flags is
set, alloc_flags will be overwritten and ALLOC_KSWAPD is thus lost.
Preserve the ALLOC_KSWAPD flag in alloc_flags to ensure kswapd won't
go to sleep accidentally.

Fixes: 0a79cdad5eb2 ("mm: use alloc_flags to record if kswapd can wake")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
---
 mm/page_alloc.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index ef3f51c9815d..35e18514215a 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5148,7 +5148,8 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
 
 	reserve_flags = __gfp_pfmemalloc_flags(gfp_mask);
 	if (reserve_flags)
-		alloc_flags = gfp_to_alloc_flags_cma(gfp_mask, reserve_flags);
+		alloc_flags = gfp_to_alloc_flags_cma(gfp_mask, reserve_flags) |
+					  (alloc_flags & ALLOC_KSWAPD);
 
 	/*
 	 * Reset the nodemask and zonelist iterators if memory policies can be
-- 
2.23.0

[PATCH v2 02/16] mm/page_alloc: make zone_pcp_update() static

[Miaohe Lin]

Since commit b92ca18e8ca5 ("mm/page_alloc: disassociate the pcp->high
from pcp->batch"), zone_pcp_update() is only used in mm/page_alloc.c.
Move zone_pcp_update() up to avoid forward declaration and then make
it static. No functional change intended.

Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
---
 mm/internal.h   |  1 -
 mm/page_alloc.c | 22 +++++++++++-----------
 2 files changed, 11 insertions(+), 12 deletions(-)

diff --git a/mm/internal.h b/mm/internal.h
index 883b09f02404..94d8a976c2e2 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -367,7 +367,6 @@ extern int user_min_free_kbytes;
 extern void free_unref_page(struct page *page, unsigned int order);
 extern void free_unref_page_list(struct list_head *list);
 
-extern void zone_pcp_update(struct zone *zone, int cpu_online);
 extern void zone_pcp_reset(struct zone *zone);
 extern void zone_pcp_disable(struct zone *zone);
 extern void zone_pcp_enable(struct zone *zone);
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 35e18514215a..04559870ed12 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -7234,6 +7234,17 @@ void __meminit setup_zone_pageset(struct zone *zone)
 	zone_set_pageset_high_and_batch(zone, 0);
 }
 
+/*
+ * The zone indicated has a new number of managed_pages; batch sizes and percpu
+ * page high values need to be recalculated.
+ */
+static void zone_pcp_update(struct zone *zone, int cpu_online)
+{
+	mutex_lock(&pcp_batch_high_lock);
+	zone_set_pageset_high_and_batch(zone, cpu_online);
+	mutex_unlock(&pcp_batch_high_lock);
+}
+
 /*
  * Allocate per cpu pagesets and initialize them.
  * Before this call only boot pagesets were available.
@@ -9465,17 +9476,6 @@ void free_contig_range(unsigned long pfn, unsigned long nr_pages)
 }
 EXPORT_SYMBOL(free_contig_range);
 
-/*
- * The zone indicated has a new number of managed_pages; batch sizes and percpu
- * page high values need to be recalculated.
- */
-void zone_pcp_update(struct zone *zone, int cpu_online)
-{
-	mutex_lock(&pcp_batch_high_lock);
-	zone_set_pageset_high_and_batch(zone, cpu_online);
-	mutex_unlock(&pcp_batch_high_lock);
-}
-
 /*
  * Effectively disable pcplists for the zone by setting the high limit to 0
  * and draining all cpus. A concurrent page freeing on another CPU that's about
-- 
2.23.0

[PATCH v2 03/16] mm: remove obsolete macro NR_PCP_ORDER_MASK and NR_PCP_ORDER_WIDTH

[Miaohe Lin]

Since commit 8b10b465d0e1 ("mm/page_alloc: free pages in a single pass
during bulk free"), they're not used anymore. Remove them.

Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
---
 include/linux/mmzone.h | 7 -------
 mm/page_alloc.c        | 1 -
 2 files changed, 8 deletions(-)

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index d907a29cc429..93f9aa346724 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -564,13 +564,6 @@ enum zone_watermarks {
 #define NR_LOWORDER_PCP_LISTS (MIGRATE_PCPTYPES * (PAGE_ALLOC_COSTLY_ORDER + 1))
 #define NR_PCP_LISTS (NR_LOWORDER_PCP_LISTS + NR_PCP_THP)
 
-/*
- * Shift to encode migratetype and order in the same integer, with order
- * in the least significant bits.
- */
-#define NR_PCP_ORDER_WIDTH 8
-#define NR_PCP_ORDER_MASK ((1<<NR_PCP_ORDER_WIDTH) - 1)
-
 #define min_wmark_pages(z) (z->_watermark[WMARK_MIN] + z->watermark_boost)
 #define low_wmark_pages(z) (z->_watermark[WMARK_LOW] + z->watermark_boost)
 #define high_wmark_pages(z) (z->_watermark[WMARK_HIGH] + z->watermark_boost)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 04559870ed12..bb2906829599 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1584,7 +1584,6 @@ static void free_pcppages_bulk(struct zone *zone, int count,
 
 		order = pindex_to_order(pindex);
 		nr_pages = 1 << order;
-		BUILD_BUG_ON(MAX_ORDER >= (1<<NR_PCP_ORDER_WIDTH));
 		do {
 			int mt;
 
-- 
2.23.0

[PATCH v2 04/16] mm/page_alloc: remove obsolete comment in zone_statistics()

[Miaohe Lin]

Since commit 43c95bcc51e4 ("mm/page_alloc: reduce duration that IRQs
are disabled for VM counters"), zone_statistics() is not called with
interrupts disabled. Update the corresponding comment.

Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
---
 mm/page_alloc.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index bb2906829599..762619463bb5 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3671,8 +3671,6 @@ void __putback_isolated_page(struct page *page, unsigned int order, int mt)
 
 /*
  * Update NUMA hit/miss statistics
- *
- * Must be called with interrupts disabled.
  */
 static inline void zone_statistics(struct zone *preferred_zone, struct zone *z,
 				   long nr_account)
-- 
2.23.0

[PATCH v2 05/16] mm/page_alloc: add __init annotations to init_mem_debugging_and_hardening()

[Miaohe Lin]

It's only called by mm_init(). Add __init annotations to it.

Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
---
 include/linux/mm.h | 2 +-
 mm/page_alloc.c    | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 364bcadb4d20..c2277f5aba9e 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -3093,7 +3093,7 @@ extern int apply_to_existing_page_range(struct mm_struct *mm,
 				   unsigned long address, unsigned long size,
 				   pte_fn_t fn, void *data);
 
-extern void init_mem_debugging_and_hardening(void);
+extern void __init init_mem_debugging_and_hardening(void);
 #ifdef CONFIG_PAGE_POISONING
 extern void __kernel_poison_pages(struct page *page, int numpages);
 extern void __kernel_unpoison_pages(struct page *page, int numpages);
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 762619463bb5..27ef763bb59f 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -903,7 +903,7 @@ static inline void clear_page_guard(struct zone *zone, struct page *page,
  * order of appearance. So we need to first gather the full picture of what was
  * enabled, and then make decisions.
  */
-void init_mem_debugging_and_hardening(void)
+void __init init_mem_debugging_and_hardening(void)
 {
 	bool page_poisoning_requested = false;
 
-- 
2.23.0

[PATCH v2 06/16] mm/page_alloc: fix freeing static percpu memory

[Miaohe Lin]

The size of struct per_cpu_zonestat can be 0 on !SMP && !NUMA. In that
case, zone->per_cpu_zonestats will always equal to boot_zonestats. But
in zone_pcp_reset(), zone->per_cpu_zonestats is freed via free_percpu()
directly without checking against boot_zonestats first. boot_zonestats
will be released by free_percpu() unexpectedly.

Fixes: 28f836b6777b ("mm/page_alloc: split per cpu page lists and zone stats")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
---
 mm/page_alloc.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 27ef763bb59f..cad235770948 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -9505,9 +9505,11 @@ void zone_pcp_reset(struct zone *zone)
 			drain_zonestat(zone, pzstats);
 		}
 		free_percpu(zone->per_cpu_pageset);
-		free_percpu(zone->per_cpu_zonestats);
 		zone->per_cpu_pageset = &boot_pageset;
-		zone->per_cpu_zonestats = &boot_zonestats;
+		if (zone->per_cpu_zonestats != &boot_zonestats) {
+			free_percpu(zone->per_cpu_zonestats);
+			zone->per_cpu_zonestats = &boot_zonestats;
+		}
 	}
 }
 
-- 
2.23.0

[PATCH v2 07/16] mm: remove obsolete pgdat_is_empty()

[Miaohe Lin]

There's no caller. Remove it.

Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
---
 include/linux/mmzone.h | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 93f9aa346724..2b3f273faf68 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -1241,11 +1241,6 @@ static inline unsigned long pgdat_end_pfn(pg_data_t *pgdat)
 	return pgdat->node_start_pfn + pgdat->node_spanned_pages;
 }
 
-static inline bool pgdat_is_empty(pg_data_t *pgdat)
-{
-	return !pgdat->node_start_pfn && !pgdat->node_spanned_pages;
-}
-
 #include <linux/memory_hotplug.h>
 
 void build_all_zonelists(pg_data_t *pgdat);
-- 
2.23.0

[PATCH v2 08/16] mm/page_alloc: add missing is_migrate_isolate() check in set_page_guard()

[Miaohe Lin]

In MIGRATE_ISOLATE case, zone freepage state shouldn't be modified as
caller will take care of it. Add missing is_migrate_isolate() here to
avoid possible unbalanced freepage state. This would happen if someone
isolates the block, and then we face an MCE failure/soft-offline on a
page within that block. __mod_zone_freepage_state() will be triggered
via below call trace which already had been triggered back when block
was isolated:

take_page_off_buddy
  break_down_buddy_pages
    set_page_guard

Fixes: 06be6ff3d2ec ("mm,hwpoison: rework soft offline for free pages")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
---
 mm/page_alloc.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index cad235770948..8fcc905ef317 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -873,7 +873,8 @@ static inline bool set_page_guard(struct zone *zone, struct page *page,
 	INIT_LIST_HEAD(&page->buddy_list);
 	set_page_private(page, order);
 	/* Guard pages are not available for any usage */
-	__mod_zone_freepage_state(zone, -(1 << order), migratetype);
+	if (!is_migrate_isolate(migratetype))
+		__mod_zone_freepage_state(zone, -(1 << order), migratetype);
 
 	return true;
 }
-- 
2.23.0

Re: [PATCH v2 08/16] mm/page_alloc: add missing is_migrate_isolate() check in set_page_guard()

[David Hildenbrand]

On 16.09.22 09:22, Miaohe Lin wrote:
> In MIGRATE_ISOLATE case, zone freepage state shouldn't be modified as
> caller will take care of it. Add missing is_migrate_isolate() here to
> avoid possible unbalanced freepage state. This would happen if someone
> isolates the block, and then we face an MCE failure/soft-offline on a
> page within that block. __mod_zone_freepage_state() will be triggered
> via below call trace which already had been triggered back when block
> was isolated:
> 
> take_page_off_buddy
>    break_down_buddy_pages
>      set_page_guard
> 
> Fixes: 06be6ff3d2ec ("mm,hwpoison: rework soft offline for free pages")
> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
> Reviewed-by: Oscar Salvador <osalvador@suse.de>
> ---

Reviewed-by: David Hildenbrand <david@redhat.com>

-- 
Thanks,

David / dhildenb

[PATCH v2 09/16] mm/page_alloc: use local variable zone_idx directly

[Miaohe Lin]

Use local variable zone_idx directly since it holds the exact value of
zone_idx(). No functional change intended.

Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
---
 mm/page_alloc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 8fcc905ef317..83b2cb93d6fd 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -6873,7 +6873,7 @@ void __ref memmap_init_zone_device(struct zone *zone,
 	unsigned long start = jiffies;
 	int nid = pgdat->node_id;
 
-	if (WARN_ON_ONCE(!pgmap || zone_idx(zone) != ZONE_DEVICE))
+	if (WARN_ON_ONCE(!pgmap || zone_idx != ZONE_DEVICE))
 		return;
 
 	/*
-- 
2.23.0

[PATCH v2 10/16] mm, memory_hotplug: remove obsolete generic_free_nodedata()

[Miaohe Lin]

Commit 390511e1476e ("mm, memory_hotplug: drop arch_free_nodedata")
drops the last caller of generic_free_nodedata(). Remove it too.

Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
---
 include/linux/memory_hotplug.h | 8 --------
 1 file changed, 8 deletions(-)

diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index 51052969dbfe..9fcbf5706595 100644
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -43,11 +43,6 @@ extern void arch_refresh_nodedata(int nid, pg_data_t *pgdat);
 ({								\
 	memblock_alloc(sizeof(*pgdat), SMP_CACHE_BYTES);	\
 })
-/*
- * This definition is just for error path in node hotadd.
- * For node hotremove, we have to replace this.
- */
-#define generic_free_nodedata(pgdat)	kfree(pgdat)
 
 extern pg_data_t *node_data[];
 static inline void arch_refresh_nodedata(int nid, pg_data_t *pgdat)
@@ -63,9 +58,6 @@ static inline pg_data_t *generic_alloc_nodedata(int nid)
 	BUG();
 	return NULL;
 }
-static inline void generic_free_nodedata(pg_data_t *pgdat)
-{
-}
 static inline void arch_refresh_nodedata(int nid, pg_data_t *pgdat)
 {
 }
-- 
2.23.0

[PATCH v2 11/16] mm/page_alloc: make boot_nodestats static

[Miaohe Lin]

It's only used in mm/page_alloc.c now. Make it static.

Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
---
 mm/internal.h   | 2 --
 mm/page_alloc.c | 2 +-
 2 files changed, 1 insertion(+), 3 deletions(-)

diff --git a/mm/internal.h b/mm/internal.h
index 94d8a976c2e2..b3002e03c28f 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -836,8 +836,6 @@ int migrate_device_coherent_page(struct page *page);
  */
 struct folio *try_grab_folio(struct page *page, int refs, unsigned int flags);
 
-DECLARE_PER_CPU(struct per_cpu_nodestat, boot_nodestats);
-
 extern bool mirrored_kernelcore;
 
 static inline bool vma_soft_dirty_enabled(struct vm_area_struct *vma)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 83b2cb93d6fd..6bdc98c7019f 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -6571,7 +6571,7 @@ static void per_cpu_pages_init(struct per_cpu_pages *pcp, struct per_cpu_zonesta
 #define BOOT_PAGESET_BATCH	1
 static DEFINE_PER_CPU(struct per_cpu_pages, boot_pageset);
 static DEFINE_PER_CPU(struct per_cpu_zonestat, boot_zonestats);
-DEFINE_PER_CPU(struct per_cpu_nodestat, boot_nodestats);
+static DEFINE_PER_CPU(struct per_cpu_nodestat, boot_nodestats);
 
 static void __build_all_zonelists(void *data)
 {
-- 
2.23.0

[PATCH v2 12/16] mm/page_alloc: use helper macro SZ_1{K,M}

[Miaohe Lin]

Use helper macro SZ_1K and SZ_1M to do the size conversion. Minor
readability improvement.

Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
---
 mm/page_alloc.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 6bdc98c7019f..67ec8a2e1db2 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -7048,7 +7048,7 @@ static int zone_batchsize(struct zone *zone)
 	 * size is striking a balance between allocation latency
 	 * and zone lock contention.
 	 */
-	batch = min(zone_managed_pages(zone) >> 10, (1024 * 1024) / PAGE_SIZE);
+	batch = min(zone_managed_pages(zone) >> 10, SZ_1M / PAGE_SIZE);
 	batch /= 4;		/* We effectively *= 4 below */
 	if (batch < 1)
 		batch = 1;
@@ -8523,8 +8523,8 @@ void __init mem_init_print_info(void)
 #endif
 		")\n",
 		K(nr_free_pages()), K(physpages),
-		codesize >> 10, datasize >> 10, rosize >> 10,
-		(init_data_size + init_code_size) >> 10, bss_size >> 10,
+		codesize / SZ_1K, datasize / SZ_1K, rosize / SZ_1K,
+		(init_data_size + init_code_size) / SZ_1K, bss_size / SZ_1K,
 		K(physpages - totalram_pages() - totalcma_pages),
 		K(totalcma_pages)
 #ifdef	CONFIG_HIGHMEM
@@ -9049,8 +9049,8 @@ void *__init alloc_large_system_hash(const char *tablename,
 		numentries -= arch_reserved_kernel_pages();
 
 		/* It isn't necessary when PAGE_SIZE >= 1MB */
-		if (PAGE_SHIFT < 20)
-			numentries = round_up(numentries, (1<<20)/PAGE_SIZE);
+		if (PAGE_SIZE < SZ_1M)
+			numentries = round_up(numentries, SZ_1M / PAGE_SIZE);
 
 #if __BITS_PER_LONG > 32
 		if (!high_limit) {
-- 
2.23.0

Re: [PATCH v2 12/16] mm/page_alloc: use helper macro SZ_1{K,M}

[David Hildenbrand]

On 16.09.22 09:22, Miaohe Lin wrote:
> Use helper macro SZ_1K and SZ_1M to do the size conversion. Minor
> readability improvement.
> 
> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
> ---

Reviewed-by: David Hildenbrand <david@redhat.com>

-- 
Thanks,

David / dhildenb

[PATCH v2 13/16] mm/page_alloc: init local variable buddy_pfn

[Miaohe Lin]

The local variable buddy_pfn could be passed to buddy_merge_likely()
without initialization if the passed in order is MAX_ORDER - 1. This
looks buggy but buddy_pfn won't be used in this case as there's a
order >= MAX_ORDER - 2 check. Init buddy_pfn to 0 anyway to avoid
possible future misuse.

Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
---
 mm/page_alloc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 67ec8a2e1db2..652b3d766003 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1113,7 +1113,7 @@ static inline void __free_one_page(struct page *page,
 		int migratetype, fpi_t fpi_flags)
 {
 	struct capture_control *capc = task_capc(zone);
-	unsigned long buddy_pfn;
+	unsigned long buddy_pfn = 0;
 	unsigned long combined_pfn;
 	struct page *buddy;
 	bool to_tail;
-- 
2.23.0

[PATCH v2 14/16] mm/page_alloc: use costly_order in WARN_ON_ONCE_GFP()

[Miaohe Lin]

There's no need to check whether order > PAGE_ALLOC_COSTLY_ORDER again.
Minor readability improvement.

Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
---
 mm/page_alloc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 652b3d766003..3d2ad5c197d5 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5272,7 +5272,7 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
 		 * so that we can identify them and convert them to something
 		 * else.
 		 */
-		WARN_ON_ONCE_GFP(order > PAGE_ALLOC_COSTLY_ORDER, gfp_mask);
+		WARN_ON_ONCE_GFP(costly_order, gfp_mask);
 
 		/*
 		 * Help non-failing allocations by giving them access to memory
-- 
2.23.0

[PATCH v2 15/16] mm/page_alloc: remove obsolete gfpflags_normal_context()

[Miaohe Lin]

Since commit dacb5d8875cc ("tcp: fix page frag corruption on page
fault"), there's no caller of gfpflags_normal_context(). Remove it
as this helper is strictly tied to the sk page frag usage and there
won't be other user in the future.

Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
---
 include/linux/gfp.h | 23 -----------------------
 1 file changed, 23 deletions(-)

diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index ea6cb9399152..ef4aea3b356e 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -36,29 +36,6 @@ static inline bool gfpflags_allow_blocking(const gfp_t gfp_flags)
 	return !!(gfp_flags & __GFP_DIRECT_RECLAIM);
 }
 
-/**
- * gfpflags_normal_context - is gfp_flags a normal sleepable context?
- * @gfp_flags: gfp_flags to test
- *
- * Test whether @gfp_flags indicates that the allocation is from the
- * %current context and allowed to sleep.
- *
- * An allocation being allowed to block doesn't mean it owns the %current
- * context.  When direct reclaim path tries to allocate memory, the
- * allocation context is nested inside whatever %current was doing at the
- * time of the original allocation.  The nested allocation may be allowed
- * to block but modifying anything %current owns can corrupt the outer
- * context's expectations.
- *
- * %true result from this function indicates that the allocation context
- * can sleep and use anything that's associated with %current.
- */
-static inline bool gfpflags_normal_context(const gfp_t gfp_flags)
-{
-	return (gfp_flags & (__GFP_DIRECT_RECLAIM | __GFP_MEMALLOC)) ==
-		__GFP_DIRECT_RECLAIM;
-}
-
 #ifdef CONFIG_HIGHMEM
 #define OPT_ZONE_HIGHMEM ZONE_HIGHMEM
 #else
-- 
2.23.0

[PATCH v2 16/16] mm/page_alloc: fix obsolete comment in deferred_pfn_valid()

[Miaohe Lin]

There are no architectures that can have holes in the memory map within
a pageblock since commit 859a85ddf90e ("mm: remove pfn_valid_within()
and CONFIG_HOLES_IN_ZONE"). Update the corresponding comment.

Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
---
 mm/page_alloc.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 3d2ad5c197d5..d7b20bf09c1c 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1929,11 +1929,7 @@ static inline void __init pgdat_init_report_one_done(void)
 /*
  * Returns true if page needs to be initialized or freed to buddy allocator.
  *
- * First we check if pfn is valid on architectures where it is possible to have
- * holes within pageblock_nr_pages. On systems where it is not possible, this
- * function is optimized out.
- *
- * Then, we check if a current large page is valid by only checking the validity
+ * We check if a current large page is valid by only checking the validity
  * of the head pfn.
  */
 static inline bool __init deferred_pfn_valid(unsigned long pfn)
-- 
2.23.0