[PATCH v1 0/1] Report perpage metadata information.

[PATCH v1 0/1] Report perpage metadata information.

[Sourav Panda]

Hi!

This patch adds a new per-node PageMetadata field to
/sys/devices/system/node/nodeN/meminfo and a global PageMetadata field
to /proc/meminfo. This information can be used by users to see how much
memory is being used by per-page metadata, which can vary depending on
build configuration, machine architecture, and system use.

Per-page metadata is the amount of memory that Linux needs in order to
manage memory at the page granularity. The majority of such memory is
used by "struct page" and "page_ext" data structures.


Background
----------

Kernel overhead observability is missing some of the largest
allocations during runtime, including vmemmap (struct pages) and
page_ext. This patch aims to address this problem by exporting a
new metric PageMetadata.

On the contrary, the kernel does provide observibility for boot memory
allocations. For example, the metric reserved_pages depicts the pages
allocated by the bootmem allocator. This can be simply calculated as
present_pages - managed_pages, which are both exported in /proc/zoneinfo.
The metric reserved_pages is primarily composed of struct pages and
page_ext.

What about the struct pages (allocated by bootmem allocator) that are
free'd during hugetlbfs allocations and then allocated by buddy-allocator
once hugtlbfs pages are free'd?

/proc/meminfo MemTotal changes: MemTotal does not include memblock
allocations but includes buddy allocations. However, during runtime
memblock allocations can be shifted into buddy allocations, and therefore
become part of MemTotal.

Once the struct pages get allocated by buddy allocator, we lose track of
these struct page allocations overhead accounting. Therefore, we must
export a new metric that we shall refer to as PageMetadata (exported by
node). This shall also comprise the struct page and page_ext allocations
made during runtime.

Results and analysis
--------------------

Memory model: Sparsemem-vmemmap
$ echo 1 > /proc/sys/vm/hugetlb_optimize_vmemmap

$ cat /proc/meminfo | grep MemTotal
	MemTotal:       32918196 kB
$ cat /proc/meminfo | grep Meta
	PageMetadata:     589824 kB
$ cat /sys/devices/system/node/node0/meminfo | grep Meta
	Node 0 PageMetadata:     294912 kB
$ cat /sys/devices/system/node/node1/meminfo | grep Meta
	Node 1 PageMetadata:     294912 kB


AFTER HUGTLBFS RESERVATION
$ echo 512 > /proc/sys/vm/nr_hugepages

$ cat /proc/meminfo | grep MemTotal

MemTotal:       32934580 kB
$ cat /proc/meminfo | grep Meta
PageMetadata:     575488 kB
$ cat /sys/devices/system/node/node0/meminfo | grep Meta
Node 0 PageMetadata:     287744 kB
$ cat /sys/devices/system/node/node1/meminfo | grep Meta
Node 1 PageMetadata:     287744 kB

AFTER FREEING HUGTLBFS RESERVATION
$ echo 0 > /proc/sys/vm/nr_hugepages
$ cat /proc/meminfo | grep MemTotal
MemTotal:       32934580 kB
$ cat /proc/meminfo | grep Meta
PageMetadata:    589824 kB
$ cat /sys/devices/system/node/node0/meminfo | grep Meta
Node 0 PageMetadata:       294912 kB
$ cat /sys/devices/system/node/node1/meminfo | grep Meta
Node 1 PageMetadata:       294912 kB

Sourav Panda (1):
  mm: report per-page metadata information

 Documentation/filesystems/proc.rst |  3 +++
 drivers/base/node.c                |  2 ++
 fs/proc/meminfo.c                  |  7 +++++++
 include/linux/mmzone.h             |  3 +++
 include/linux/vmstat.h             |  4 ++++
 mm/hugetlb.c                       |  8 +++++++-
 mm/hugetlb_vmemmap.c               |  9 ++++++++-
 mm/mm_init.c                       |  3 +++
 mm/page_alloc.c                    |  1 +
 mm/page_ext.c                      | 17 +++++++++++++----
 mm/sparse-vmemmap.c                |  3 +++
 mm/sparse.c                        |  7 ++++++-
 mm/vmstat.c                        | 21 +++++++++++++++++++++
 13 files changed, 81 insertions(+), 7 deletions(-)

-- 
2.42.0.283.g2d96d420d3-goog

[PATCH v1 1/1] mm: report per-page metadata information

[Sourav Panda]

Adds a new per-node PageMetadata field to
/sys/devices/system/node/nodeN/meminfo
and a global PageMetadata field to /proc/meminfo. This information can
be used by users to see how much memory is being used by per-page
metadata, which can vary depending on build configuration, machine
architecture, and system use.

Per-page metadata is the amount of memory that Linux needs in order to
manage memory at the page granularity. The majority of such memory is
used by "struct page" and "page_ext" data structures.

This memory depends on build configurations, machine architectures, and
the way system is used:

Build configuration may include extra fields into "struct page",
and enable / disable "page_ext"
Machine architecture defines base page sizes. For example 4K x86,
8K SPARC, 64K ARM64 (optionally), etc. The per-page metadata
overhead is smaller on machines with larger page sizes.
System use can change per-page overhead by using vmemmap
optimizations with hugetlb pages, and emulated pmem devdax pages.
Also, boot parameters can determine whether page_ext is needed
to be allocated. This memory can be part of MemTotal or be outside
MemTotal depending on whether the memory was hot-plugged, booted with,
or hugetlb memory was returned back to the system.

Suggested-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Sourav Panda <souravpanda@google.com>
---
 Documentation/filesystems/proc.rst |  3 +++
 drivers/base/node.c                |  2 ++
 fs/proc/meminfo.c                  |  7 +++++++
 include/linux/mmzone.h             |  3 +++
 include/linux/vmstat.h             |  4 ++++
 mm/hugetlb.c                       |  8 +++++++-
 mm/hugetlb_vmemmap.c               |  9 ++++++++-
 mm/mm_init.c                       |  3 +++
 mm/page_alloc.c                    |  1 +
 mm/page_ext.c                      | 17 +++++++++++++----
 mm/sparse-vmemmap.c                |  3 +++
 mm/sparse.c                        |  7 ++++++-
 mm/vmstat.c                        | 21 +++++++++++++++++++++
 13 files changed, 81 insertions(+), 7 deletions(-)

diff --git a/Documentation/filesystems/proc.rst b/Documentation/filesystems/proc.rst
index 2b59cff8be17..c121f2ef9432 100644
--- a/Documentation/filesystems/proc.rst
+++ b/Documentation/filesystems/proc.rst
@@ -987,6 +987,7 @@ Example output. You may not have all of these fields.
     AnonPages:       4654780 kB
     Mapped:           266244 kB
     Shmem:              9976 kB
+    PageMetadata:     513419 kB
     KReclaimable:     517708 kB
     Slab:             660044 kB
     SReclaimable:     517708 kB
@@ -1089,6 +1090,8 @@ Mapped
               files which have been mmapped, such as libraries
 Shmem
               Total memory used by shared memory (shmem) and tmpfs
+PageMetadata
+              Memory used for per-page metadata
 KReclaimable
               Kernel allocations that the kernel will attempt to reclaim
               under memory pressure. Includes SReclaimable (below), and other
diff --git a/drivers/base/node.c b/drivers/base/node.c
index 493d533f8375..da728542265f 100644
--- a/drivers/base/node.c
+++ b/drivers/base/node.c
@@ -428,6 +428,7 @@ static ssize_t node_read_meminfo(struct device *dev,
 			     "Node %d Mapped:         %8lu kB\n"
 			     "Node %d AnonPages:      %8lu kB\n"
 			     "Node %d Shmem:          %8lu kB\n"
+			     "Node %d PageMetadata:   %8lu kB\n"
 			     "Node %d KernelStack:    %8lu kB\n"
 #ifdef CONFIG_SHADOW_CALL_STACK
 			     "Node %d ShadowCallStack:%8lu kB\n"
@@ -458,6 +459,7 @@ static ssize_t node_read_meminfo(struct device *dev,
 			     nid, K(node_page_state(pgdat, NR_FILE_MAPPED)),
 			     nid, K(node_page_state(pgdat, NR_ANON_MAPPED)),
 			     nid, K(i.sharedram),
+			     nid, K(node_page_state(pgdat, NR_PAGE_METADATA)),
 			     nid, node_page_state(pgdat, NR_KERNEL_STACK_KB),
 #ifdef CONFIG_SHADOW_CALL_STACK
 			     nid, node_page_state(pgdat, NR_KERNEL_SCS_KB),
diff --git a/fs/proc/meminfo.c b/fs/proc/meminfo.c
index 45af9a989d40..f141bb2a550d 100644
--- a/fs/proc/meminfo.c
+++ b/fs/proc/meminfo.c
@@ -39,7 +39,9 @@ static int meminfo_proc_show(struct seq_file *m, void *v)
 	long available;
 	unsigned long pages[NR_LRU_LISTS];
 	unsigned long sreclaimable, sunreclaim;
+	unsigned long nr_page_metadata;
 	int lru;
+	int nid;
 
 	si_meminfo(&i);
 	si_swapinfo(&i);
@@ -57,6 +59,10 @@ static int meminfo_proc_show(struct seq_file *m, void *v)
 	sreclaimable = global_node_page_state_pages(NR_SLAB_RECLAIMABLE_B);
 	sunreclaim = global_node_page_state_pages(NR_SLAB_UNRECLAIMABLE_B);
 
+	nr_page_metadata = 0;
+	for_each_online_node(nid)
+		nr_page_metadata += node_page_state(NODE_DATA(nid), NR_PAGE_METADATA);
+
 	show_val_kb(m, "MemTotal:       ", i.totalram);
 	show_val_kb(m, "MemFree:        ", i.freeram);
 	show_val_kb(m, "MemAvailable:   ", available);
@@ -104,6 +110,7 @@ static int meminfo_proc_show(struct seq_file *m, void *v)
 	show_val_kb(m, "Mapped:         ",
 		    global_node_page_state(NR_FILE_MAPPED));
 	show_val_kb(m, "Shmem:          ", i.sharedram);
+	show_val_kb(m, "PageMetadata:   ", nr_page_metadata);
 	show_val_kb(m, "KReclaimable:   ", sreclaimable +
 		    global_node_page_state(NR_KERNEL_MISC_RECLAIMABLE));
 	show_val_kb(m, "Slab:           ", sreclaimable + sunreclaim);
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 4106fbc5b4b3..dda1ad522324 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -207,6 +207,9 @@ enum node_stat_item {
 	PGPROMOTE_SUCCESS,	/* promote successfully */
 	PGPROMOTE_CANDIDATE,	/* candidate pages to promote */
 #endif
+	NR_PAGE_METADATA,	/* Page metadata size (struct page and page_ext)
+				 * in pages
+				 */
 	NR_VM_NODE_STAT_ITEMS
 };
 
diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h
index fed855bae6d8..b5c292560f37 100644
--- a/include/linux/vmstat.h
+++ b/include/linux/vmstat.h
@@ -656,4 +656,8 @@ static inline void lruvec_stat_sub_folio(struct folio *folio,
 {
 	lruvec_stat_mod_folio(folio, idx, -folio_nr_pages(folio));
 }
+
+void __init mod_node_early_perpage_metadata(int nid, long delta);
+void __init writeout_early_perpage_metadata(void);
+
 #endif /* _LINUX_VMSTAT_H */
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index ba6d39b71cb1..ca36751be50e 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1758,6 +1758,10 @@ static void __update_and_free_hugetlb_folio(struct hstate *h,
 		destroy_compound_gigantic_folio(folio, huge_page_order(h));
 		free_gigantic_folio(folio, huge_page_order(h));
 	} else {
+#ifndef CONFIG_SPARSEMEM_VMEMMAP
+		__mod_node_page_state(NODE_DATA(page_to_nid(&folio->page)),
+				      NR_PAGE_METADATA, -huge_page_order(h));
+#endif
 		__free_pages(&folio->page, huge_page_order(h));
 	}
 }
@@ -2143,7 +2147,9 @@ static struct folio *alloc_buddy_hugetlb_folio(struct hstate *h,
 		__count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
 		return NULL;
 	}
-
+#ifndef CONFIG_SPARSEMEM_VMEMMAP
+	__mod_node_page_state(NODE_DATA(nid), NR_PAGE_METADATA, huge_page_order(h));
+#endif
 	__count_vm_event(HTLB_BUDDY_PGALLOC);
 	return page_folio(page);
 }
diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c
index 4b9734777f69..7f920bfa8e79 100644
--- a/mm/hugetlb_vmemmap.c
+++ b/mm/hugetlb_vmemmap.c
@@ -214,6 +214,8 @@ static inline void free_vmemmap_page(struct page *page)
 		free_bootmem_page(page);
 	else
 		__free_page(page);
+	__mod_node_page_state(NODE_DATA(page_to_nid(page)),
+			      NR_PAGE_METADATA, -1);
 }
 
 /* Free a list of the vmemmap pages */
@@ -336,6 +338,7 @@ static int vmemmap_remap_free(unsigned long start, unsigned long end,
 			  (void *)walk.reuse_addr);
 		list_add(&walk.reuse_page->lru, &vmemmap_pages);
 	}
+	__mod_node_page_state(NODE_DATA(nid), NR_PAGE_METADATA, 1);
 
 	/*
 	 * In order to make remapping routine most efficient for the huge pages,
@@ -387,8 +390,12 @@ static int alloc_vmemmap_page_list(unsigned long start, unsigned long end,
 
 	while (nr_pages--) {
 		page = alloc_pages_node(nid, gfp_mask, 0);
-		if (!page)
+		if (!page) {
 			goto out;
+		} else {
+			__mod_node_page_state(NODE_DATA(page_to_nid(page)),
+					      NR_PAGE_METADATA, 1);
+		}
 		list_add_tail(&page->lru, list);
 	}
 
diff --git a/mm/mm_init.c b/mm/mm_init.c
index 50f2f34745af..e02dce7e2e9a 100644
--- a/mm/mm_init.c
+++ b/mm/mm_init.c
@@ -26,6 +26,7 @@
 #include <linux/pgtable.h>
 #include <linux/swap.h>
 #include <linux/cma.h>
+#include <linux/vmstat.h>
 #include "internal.h"
 #include "slab.h"
 #include "shuffle.h"
@@ -1656,6 +1657,8 @@ static void __init alloc_node_mem_map(struct pglist_data *pgdat)
 			panic("Failed to allocate %ld bytes for node %d memory map\n",
 			      size, pgdat->node_id);
 		pgdat->node_mem_map = map + offset;
+		mod_node_early_perpage_metadata(pgdat->node_id,
+						PAGE_ALIGN(size) >> PAGE_SHIFT);
 	}
 	pr_debug("%s: node %d, pgdat %08lx, node_mem_map %08lx\n",
 				__func__, pgdat->node_id, (unsigned long)pgdat,
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 0c5be12f9336..4e295d5087f4 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5443,6 +5443,7 @@ void __init setup_per_cpu_pageset(void)
 	for_each_online_pgdat(pgdat)
 		pgdat->per_cpu_nodestats =
 			alloc_percpu(struct per_cpu_nodestat);
+	writeout_early_perpage_metadata();
 }
 
 __meminit void zone_pcp_init(struct zone *zone)
diff --git a/mm/page_ext.c b/mm/page_ext.c
index 4548fcc66d74..b5b9d3079e20 100644
--- a/mm/page_ext.c
+++ b/mm/page_ext.c
@@ -201,6 +201,8 @@ static int __init alloc_node_page_ext(int nid)
 		return -ENOMEM;
 	NODE_DATA(nid)->node_page_ext = base;
 	total_usage += table_size;
+	__mod_node_page_state(NODE_DATA(nid), NR_PAGE_METADATA,
+			      PAGE_ALIGN(table_size) >> PAGE_SHIFT);
 	return 0;
 }
 
@@ -255,12 +257,15 @@ static void *__meminit alloc_page_ext(size_t size, int nid)
 	void *addr = NULL;
 
 	addr = alloc_pages_exact_nid(nid, size, flags);
-	if (addr) {
+	if (addr)
 		kmemleak_alloc(addr, size, 1, flags);
-		return addr;
-	}
+	else
+		addr = vzalloc_node(size, nid);
 
-	addr = vzalloc_node(size, nid);
+	if (addr) {
+		__mod_node_page_state(NODE_DATA(nid), NR_PAGE_METADATA,
+				      PAGE_ALIGN(size) >> PAGE_SHIFT);
+	}
 
 	return addr;
 }
@@ -314,6 +319,10 @@ static void free_page_ext(void *addr)
 		BUG_ON(PageReserved(page));
 		kmemleak_free(addr);
 		free_pages_exact(addr, table_size);
+
+		__mod_node_page_state(NODE_DATA(page_to_nid(page)), NR_PAGE_METADATA,
+				      (long)-1 * (PAGE_ALIGN(table_size) >> PAGE_SHIFT));
+
 	}
 }
 
diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c
index a2cbe44c48e1..e33f302db7c6 100644
--- a/mm/sparse-vmemmap.c
+++ b/mm/sparse-vmemmap.c
@@ -469,5 +469,8 @@ struct page * __meminit __populate_section_memmap(unsigned long pfn,
 	if (r < 0)
 		return NULL;
 
+	__mod_node_page_state(NODE_DATA(nid), NR_PAGE_METADATA,
+			      PAGE_ALIGN(end - start) >> PAGE_SHIFT);
+
 	return pfn_to_page(pfn);
 }
diff --git a/mm/sparse.c b/mm/sparse.c
index 77d91e565045..db78233a85ef 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -14,7 +14,7 @@
 #include <linux/swap.h>
 #include <linux/swapops.h>
 #include <linux/bootmem_info.h>
-
+#include <linux/vmstat.h>
 #include "internal.h"
 #include <asm/dma.h>
 
@@ -465,6 +465,9 @@ static void __init sparse_buffer_init(unsigned long size, int nid)
 	 */
 	sparsemap_buf = memmap_alloc(size, section_map_size(), addr, nid, true);
 	sparsemap_buf_end = sparsemap_buf + size;
+#ifndef CONFIG_SPARSEMEM_VMEMMAP
+	mod_node_early_perpage_metadata(nid, PAGE_ALIGN(size) >> PAGE_SHIFT);
+#endif
 }
 
 static void __init sparse_buffer_fini(void)
@@ -641,6 +644,8 @@ static void depopulate_section_memmap(unsigned long pfn, unsigned long nr_pages,
 	unsigned long start = (unsigned long) pfn_to_page(pfn);
 	unsigned long end = start + nr_pages * sizeof(struct page);
 
+	__mod_node_page_state(NODE_DATA(page_to_nid(pfn_to_page(pfn))), NR_PAGE_METADATA,
+			      (long)-1 * (PAGE_ALIGN(end - start) >> PAGE_SHIFT));
 	vmemmap_free(start, end, altmap);
 }
 static void free_map_bootmem(struct page *memmap)
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 00e81e99c6ee..731eb5264b49 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1245,6 +1245,7 @@ const char * const vmstat_text[] = {
 	"pgpromote_success",
 	"pgpromote_candidate",
 #endif
+	"nr_page_metadata",
 
 	/* enum writeback_stat_item counters */
 	"nr_dirty_threshold",
@@ -2274,4 +2275,24 @@ static int __init extfrag_debug_init(void)
 }
 
 module_init(extfrag_debug_init);
+
+// Page metadata size (struct page and page_ext) in pages
+unsigned long early_perpage_metadata[MAX_NUMNODES] __initdata;
+
+void __init mod_node_early_perpage_metadata(int nid, long delta)
+{
+	early_perpage_metadata[nid] += delta;
+}
+
+void __init writeout_early_perpage_metadata(void)
+{
+	int nid;
+	struct pglist_data *pgdat;
+
+	for_each_online_pgdat(pgdat) {
+		nid = pgdat->node_id;
+		__mod_node_page_state(NODE_DATA(nid), NR_PAGE_METADATA,
+				      early_perpage_metadata[nid]);
+	}
+}
 #endif
-- 
2.42.0.283.g2d96d420d3-goog

Re: [PATCH v1 1/1] mm: report per-page metadata information

[Matthew Wilcox]

On Wed, Sep 13, 2023 at 10:30:00AM -0700, Sourav Panda wrote:
> @@ -387,8 +390,12 @@ static int alloc_vmemmap_page_list(unsigned long start, unsigned long end,
>  
>  	while (nr_pages--) {
>  		page = alloc_pages_node(nid, gfp_mask, 0);
> -		if (!page)
> +		if (!page) {
>  			goto out;
> +		} else {
> +			__mod_node_page_state(NODE_DATA(page_to_nid(page)),
> +					      NR_PAGE_METADATA, 1);
> +		}
>  		list_add_tail(&page->lru, list);

What a strange way of writing this.  Why not simply:

		if (!page)
			goto out;
+		__mod_node_page_state(NODE_DATA(page_to_nid(page)),
+				NR_PAGE_METADATA, 1);
		list_add_tail(&page->lru, list);

> @@ -314,6 +319,10 @@ static void free_page_ext(void *addr)
>  		BUG_ON(PageReserved(page));
>  		kmemleak_free(addr);
>  		free_pages_exact(addr, table_size);
> +
> +		__mod_node_page_state(NODE_DATA(page_to_nid(page)), NR_PAGE_METADATA,
> +				      (long)-1 * (PAGE_ALIGN(table_size) >> PAGE_SHIFT));

Why not spell that as "-1L"?

And while I'm asking questions, why NODE_DATA(page_to_nid(page)) instead
of page_pgdat(page)?

> @@ -2274,4 +2275,24 @@ static int __init extfrag_debug_init(void)
>  }
>  
>  module_init(extfrag_debug_init);
> +
> +// Page metadata size (struct page and page_ext) in pages

Don't use // comments.

> +void __init writeout_early_perpage_metadata(void)

"writeout" is something swap does.  I'm sure this has a better name,
though I can't think what it might be.

> +{
> +	int nid;
> +	struct pglist_data *pgdat;
> +
> +	for_each_online_pgdat(pgdat) {
> +		nid = pgdat->node_id;
> +		__mod_node_page_state(NODE_DATA(nid), NR_PAGE_METADATA,
> +				      early_perpage_metadata[nid]);
> +	}
> +}
>  #endif
> -- 
> 2.42.0.283.g2d96d420d3-goog
> 

Re: [PATCH v1 1/1] mm: report per-page metadata information

[Sourav Panda]

[-- Attachment #1: Type: text/plain, Size: 2784 bytes --]

Hi Matthew Wilcox,

Thank you very much for reviewing my patch. Please find my responses below.

On Wed, Sep 13, 2023 at 10:56 AM Matthew Wilcox <willy@infradead.org> wrote:

> On Wed, Sep 13, 2023 at 10:30:00AM -0700, Sourav Panda wrote:
> > @@ -387,8 +390,12 @@ static int alloc_vmemmap_page_list(unsigned long
> start, unsigned long end,
> >
> >       while (nr_pages--) {
> >               page = alloc_pages_node(nid, gfp_mask, 0);
> > -             if (!page)
> > +             if (!page) {
> >                       goto out;
> > +             } else {
> > +                     __mod_node_page_state(NODE_DATA(page_to_nid(page)),
> > +                                           NR_PAGE_METADATA, 1);
> > +             }
> >               list_add_tail(&page->lru, list);
>
> What a strange way of writing this.  Why not simply:
>
>                 if (!page)
>                         goto out;
> +               __mod_node_page_state(NODE_DATA(page_to_nid(page)),
> +                               NR_PAGE_METADATA, 1);
>                 list_add_tail(&page->lru, list);
>

Thank you Matthew Wilcox for your comment. I agree with you and will make
the corresponding change.


>
> > @@ -314,6 +319,10 @@ static void free_page_ext(void *addr)
> >               BUG_ON(PageReserved(page));
> >               kmemleak_free(addr);
> >               free_pages_exact(addr, table_size);
> > +
> > +             __mod_node_page_state(NODE_DATA(page_to_nid(page)),
> NR_PAGE_METADATA,
> > +                                   (long)-1 * (PAGE_ALIGN(table_size)
> >> PAGE_SHIFT));
>
> Why not spell that as "-1L"?
>
> And while I'm asking questions, why NODE_DATA(page_to_nid(page)) instead
> of page_pgdat(page)?
>

Yes, thank you! I shall make both the suggested changes.


>
> > @@ -2274,4 +2275,24 @@ static int __init extfrag_debug_init(void)
> >  }
> >
> >  module_init(extfrag_debug_init);
> > +
> > +// Page metadata size (struct page and page_ext) in pages
>
> Don't use // comments.
>

Thank you. I shall replace them with /* text */ to be uniform with the
document.


>
> > +void __init writeout_early_perpage_metadata(void)
>
> "writeout" is something swap does.  I'm sure this has a better name,
> though I can't think what it might be.
>
> > +{
> > +     int nid;
> > +     struct pglist_data *pgdat;
> > +
> > +     for_each_online_pgdat(pgdat) {
> > +             nid = pgdat->node_id;
> > +             __mod_node_page_state(NODE_DATA(nid), NR_PAGE_METADATA,
> > +                                   early_perpage_metadata[nid]);
> > +     }
> > +}
> >  #endif
> > --
> > 2.42.0.283.g2d96d420d3-goog
> >


Yep, thank you! Does store_early_perpage_metadata seem better to you?

[-- Attachment #2: Type: text/html, Size: 4149 bytes --]

Re: [PATCH v1 1/1] mm: report per-page metadata information

[kernel test robot]

Hi Sourav,

kernel test robot noticed the following build errors:

[auto build test ERROR on akpm-mm/mm-everything]
[also build test ERROR on driver-core/driver-core-testing driver-core/driver-core-next driver-core/driver-core-linus linus/master v6.6-rc1 next-20230913]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Sourav-Panda/mm-report-per-page-metadata-information/20230914-013201
base:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
patch link:    https://lore.kernel.org/r/20230913173000.4016218-2-souravpanda%40google.com
patch subject: [PATCH v1 1/1] mm: report per-page metadata information
config: i386-tinyconfig (https://download.01.org/0day-ci/archive/20230914/202309140322.cF62Kywb-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20230914/202309140322.cF62Kywb-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202309140322.cF62Kywb-lkp@intel.com/

All errors (new ones prefixed by >>):

   ld: mm/mm_init.o: in function `free_area_init':
>> mm_init.c:(.init.text+0x842): undefined reference to `mod_node_early_perpage_metadata'
   ld: mm/page_alloc.o: in function `setup_per_cpu_pageset':
>> page_alloc.c:(.init.text+0x60): undefined reference to `writeout_early_perpage_metadata'

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

Re: [PATCH v1 1/1] mm: report per-page metadata information

[Mike Rapoport]

On Wed, Sep 13, 2023 at 10:30:00AM -0700, Sourav Panda wrote:
> Adds a new per-node PageMetadata field to
> /sys/devices/system/node/nodeN/meminfo
> and a global PageMetadata field to /proc/meminfo. This information can
> be used by users to see how much memory is being used by per-page
> metadata, which can vary depending on build configuration, machine
> architecture, and system use.
> 
> Per-page metadata is the amount of memory that Linux needs in order to
> manage memory at the page granularity. The majority of such memory is
> used by "struct page" and "page_ext" data structures.
> 
> This memory depends on build configurations, machine architectures, and
> the way system is used:
> 
> Build configuration may include extra fields into "struct page",
> and enable / disable "page_ext"
> Machine architecture defines base page sizes. For example 4K x86,
> 8K SPARC, 64K ARM64 (optionally), etc. The per-page metadata
> overhead is smaller on machines with larger page sizes.
> System use can change per-page overhead by using vmemmap
> optimizations with hugetlb pages, and emulated pmem devdax pages.
> Also, boot parameters can determine whether page_ext is needed
> to be allocated. This memory can be part of MemTotal or be outside
> MemTotal depending on whether the memory was hot-plugged, booted with,
> or hugetlb memory was returned back to the system.
> 
> Suggested-by: Pasha Tatashin <pasha.tatashin@soleen.com>
> Signed-off-by: Sourav Panda <souravpanda@google.com>
> ---
>  Documentation/filesystems/proc.rst |  3 +++
>  drivers/base/node.c                |  2 ++
>  fs/proc/meminfo.c                  |  7 +++++++
>  include/linux/mmzone.h             |  3 +++
>  include/linux/vmstat.h             |  4 ++++
>  mm/hugetlb.c                       |  8 +++++++-
>  mm/hugetlb_vmemmap.c               |  9 ++++++++-
>  mm/mm_init.c                       |  3 +++
>  mm/page_alloc.c                    |  1 +
>  mm/page_ext.c                      | 17 +++++++++++++----
>  mm/sparse-vmemmap.c                |  3 +++
>  mm/sparse.c                        |  7 ++++++-
>  mm/vmstat.c                        | 21 +++++++++++++++++++++
>  13 files changed, 81 insertions(+), 7 deletions(-)
> 
> diff --git a/Documentation/filesystems/proc.rst b/Documentation/filesystems/proc.rst
> index 2b59cff8be17..c121f2ef9432 100644
> --- a/Documentation/filesystems/proc.rst
> +++ b/Documentation/filesystems/proc.rst
> @@ -987,6 +987,7 @@ Example output. You may not have all of these fields.
>      AnonPages:       4654780 kB
>      Mapped:           266244 kB
>      Shmem:              9976 kB
> +    PageMetadata:     513419 kB
>      KReclaimable:     517708 kB
>      Slab:             660044 kB
>      SReclaimable:     517708 kB
> @@ -1089,6 +1090,8 @@ Mapped
>                files which have been mmapped, such as libraries
>  Shmem
>                Total memory used by shared memory (shmem) and tmpfs
> +PageMetadata
> +              Memory used for per-page metadata
>  KReclaimable
>                Kernel allocations that the kernel will attempt to reclaim
>                under memory pressure. Includes SReclaimable (below), and other
> diff --git a/drivers/base/node.c b/drivers/base/node.c
> index 493d533f8375..da728542265f 100644
> --- a/drivers/base/node.c
> +++ b/drivers/base/node.c
> @@ -428,6 +428,7 @@ static ssize_t node_read_meminfo(struct device *dev,
>  			     "Node %d Mapped:         %8lu kB\n"
>  			     "Node %d AnonPages:      %8lu kB\n"
>  			     "Node %d Shmem:          %8lu kB\n"
> +			     "Node %d PageMetadata:   %8lu kB\n"
>  			     "Node %d KernelStack:    %8lu kB\n"
>  #ifdef CONFIG_SHADOW_CALL_STACK
>  			     "Node %d ShadowCallStack:%8lu kB\n"
> @@ -458,6 +459,7 @@ static ssize_t node_read_meminfo(struct device *dev,
>  			     nid, K(node_page_state(pgdat, NR_FILE_MAPPED)),
>  			     nid, K(node_page_state(pgdat, NR_ANON_MAPPED)),
>  			     nid, K(i.sharedram),
> +			     nid, K(node_page_state(pgdat, NR_PAGE_METADATA)),
>  			     nid, node_page_state(pgdat, NR_KERNEL_STACK_KB),
>  #ifdef CONFIG_SHADOW_CALL_STACK
>  			     nid, node_page_state(pgdat, NR_KERNEL_SCS_KB),
> diff --git a/fs/proc/meminfo.c b/fs/proc/meminfo.c
> index 45af9a989d40..f141bb2a550d 100644
> --- a/fs/proc/meminfo.c
> +++ b/fs/proc/meminfo.c
> @@ -39,7 +39,9 @@ static int meminfo_proc_show(struct seq_file *m, void *v)
>  	long available;
>  	unsigned long pages[NR_LRU_LISTS];
>  	unsigned long sreclaimable, sunreclaim;
> +	unsigned long nr_page_metadata;
>  	int lru;
> +	int nid;
>  
>  	si_meminfo(&i);
>  	si_swapinfo(&i);
> @@ -57,6 +59,10 @@ static int meminfo_proc_show(struct seq_file *m, void *v)
>  	sreclaimable = global_node_page_state_pages(NR_SLAB_RECLAIMABLE_B);
>  	sunreclaim = global_node_page_state_pages(NR_SLAB_UNRECLAIMABLE_B);
>  
> +	nr_page_metadata = 0;
> +	for_each_online_node(nid)
> +		nr_page_metadata += node_page_state(NODE_DATA(nid), NR_PAGE_METADATA);
> +
>  	show_val_kb(m, "MemTotal:       ", i.totalram);
>  	show_val_kb(m, "MemFree:        ", i.freeram);
>  	show_val_kb(m, "MemAvailable:   ", available);
> @@ -104,6 +110,7 @@ static int meminfo_proc_show(struct seq_file *m, void *v)
>  	show_val_kb(m, "Mapped:         ",
>  		    global_node_page_state(NR_FILE_MAPPED));
>  	show_val_kb(m, "Shmem:          ", i.sharedram);
> +	show_val_kb(m, "PageMetadata:   ", nr_page_metadata);
>  	show_val_kb(m, "KReclaimable:   ", sreclaimable +
>  		    global_node_page_state(NR_KERNEL_MISC_RECLAIMABLE));
>  	show_val_kb(m, "Slab:           ", sreclaimable + sunreclaim);
> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
> index 4106fbc5b4b3..dda1ad522324 100644
> --- a/include/linux/mmzone.h
> +++ b/include/linux/mmzone.h
> @@ -207,6 +207,9 @@ enum node_stat_item {
>  	PGPROMOTE_SUCCESS,	/* promote successfully */
>  	PGPROMOTE_CANDIDATE,	/* candidate pages to promote */
>  #endif
> +	NR_PAGE_METADATA,	/* Page metadata size (struct page and page_ext)
> +				 * in pages
> +				 */
>  	NR_VM_NODE_STAT_ITEMS
>  };
>  
> diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h
> index fed855bae6d8..b5c292560f37 100644
> --- a/include/linux/vmstat.h
> +++ b/include/linux/vmstat.h
> @@ -656,4 +656,8 @@ static inline void lruvec_stat_sub_folio(struct folio *folio,
>  {
>  	lruvec_stat_mod_folio(folio, idx, -folio_nr_pages(folio));
>  }
> +
> +void __init mod_node_early_perpage_metadata(int nid, long delta);
> +void __init writeout_early_perpage_metadata(void);
> +
>  #endif /* _LINUX_VMSTAT_H */
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index ba6d39b71cb1..ca36751be50e 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -1758,6 +1758,10 @@ static void __update_and_free_hugetlb_folio(struct hstate *h,
>  		destroy_compound_gigantic_folio(folio, huge_page_order(h));
>  		free_gigantic_folio(folio, huge_page_order(h));
>  	} else {
> +#ifndef CONFIG_SPARSEMEM_VMEMMAP
> +		__mod_node_page_state(NODE_DATA(page_to_nid(&folio->page)),
> +				      NR_PAGE_METADATA, -huge_page_order(h));

I don't think memory map will change here with classic SPARSEMEM

> +#endif
>  		__free_pages(&folio->page, huge_page_order(h));
>  	}
>  }
> @@ -2143,7 +2147,9 @@ static struct folio *alloc_buddy_hugetlb_folio(struct hstate *h,
>  		__count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
>  		return NULL;
>  	}
> -
> +#ifndef CONFIG_SPARSEMEM_VMEMMAP
> +	__mod_node_page_state(NODE_DATA(nid), NR_PAGE_METADATA, huge_page_order(h));
> +#endif
>  	__count_vm_event(HTLB_BUDDY_PGALLOC);
>  	return page_folio(page);
>  }
> diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c
> index 4b9734777f69..7f920bfa8e79 100644
> --- a/mm/hugetlb_vmemmap.c
> +++ b/mm/hugetlb_vmemmap.c
> @@ -214,6 +214,8 @@ static inline void free_vmemmap_page(struct page *page)
>  		free_bootmem_page(page);
>  	else
>  		__free_page(page);
> +	__mod_node_page_state(NODE_DATA(page_to_nid(page)),
> +			      NR_PAGE_METADATA, -1);
>  }
>  
>  /* Free a list of the vmemmap pages */
> @@ -336,6 +338,7 @@ static int vmemmap_remap_free(unsigned long start, unsigned long end,
>  			  (void *)walk.reuse_addr);
>  		list_add(&walk.reuse_page->lru, &vmemmap_pages);
>  	}
> +	__mod_node_page_state(NODE_DATA(nid), NR_PAGE_METADATA, 1);
>  
>  	/*
>  	 * In order to make remapping routine most efficient for the huge pages,
> @@ -387,8 +390,12 @@ static int alloc_vmemmap_page_list(unsigned long start, unsigned long end,
>  
>  	while (nr_pages--) {
>  		page = alloc_pages_node(nid, gfp_mask, 0);
> -		if (!page)
> +		if (!page) {
>  			goto out;
> +		} else {
> +			__mod_node_page_state(NODE_DATA(page_to_nid(page)),
> +					      NR_PAGE_METADATA, 1);

We can update this once for nr_pages outside the loop, cannot we?

> +		}
>  		list_add_tail(&page->lru, list);
>  	}
>  
> diff --git a/mm/mm_init.c b/mm/mm_init.c
> index 50f2f34745af..e02dce7e2e9a 100644
> --- a/mm/mm_init.c
> +++ b/mm/mm_init.c
> @@ -26,6 +26,7 @@
>  #include <linux/pgtable.h>
>  #include <linux/swap.h>
>  #include <linux/cma.h>
> +#include <linux/vmstat.h>
>  #include "internal.h"
>  #include "slab.h"
>  #include "shuffle.h"
> @@ -1656,6 +1657,8 @@ static void __init alloc_node_mem_map(struct pglist_data *pgdat)
>  			panic("Failed to allocate %ld bytes for node %d memory map\n",
>  			      size, pgdat->node_id);
>  		pgdat->node_mem_map = map + offset;
> +		mod_node_early_perpage_metadata(pgdat->node_id,
> +						PAGE_ALIGN(size) >> PAGE_SHIFT);
>  	}
>  	pr_debug("%s: node %d, pgdat %08lx, node_mem_map %08lx\n",
>  				__func__, pgdat->node_id, (unsigned long)pgdat,
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 0c5be12f9336..4e295d5087f4 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -5443,6 +5443,7 @@ void __init setup_per_cpu_pageset(void)
>  	for_each_online_pgdat(pgdat)
>  		pgdat->per_cpu_nodestats =
>  			alloc_percpu(struct per_cpu_nodestat);
> +	writeout_early_perpage_metadata();

Why it's called here?
You can copy early stats to actual node stats as soon as the nodes and page
allocator are initialized.

>  }
>  
>  __meminit void zone_pcp_init(struct zone *zone)
> diff --git a/mm/page_ext.c b/mm/page_ext.c
> index 4548fcc66d74..b5b9d3079e20 100644
> --- a/mm/page_ext.c
> +++ b/mm/page_ext.c
> @@ -201,6 +201,8 @@ static int __init alloc_node_page_ext(int nid)
>  		return -ENOMEM;
>  	NODE_DATA(nid)->node_page_ext = base;
>  	total_usage += table_size;
> +	__mod_node_page_state(NODE_DATA(nid), NR_PAGE_METADATA,
> +			      PAGE_ALIGN(table_size) >> PAGE_SHIFT);
>  	return 0;
>  }
>  
> @@ -255,12 +257,15 @@ static void *__meminit alloc_page_ext(size_t size, int nid)
>  	void *addr = NULL;
>  
>  	addr = alloc_pages_exact_nid(nid, size, flags);
> -	if (addr) {
> +	if (addr)
>  		kmemleak_alloc(addr, size, 1, flags);
> -		return addr;
> -	}
> +	else
> +		addr = vzalloc_node(size, nid);
>  
> -	addr = vzalloc_node(size, nid);
> +	if (addr) {
> +		__mod_node_page_state(NODE_DATA(nid), NR_PAGE_METADATA,
> +				      PAGE_ALIGN(size) >> PAGE_SHIFT);
> +	}
>  
>  	return addr;
>  }
> @@ -314,6 +319,10 @@ static void free_page_ext(void *addr)
>  		BUG_ON(PageReserved(page));
>  		kmemleak_free(addr);
>  		free_pages_exact(addr, table_size);
> +
> +		__mod_node_page_state(NODE_DATA(page_to_nid(page)), NR_PAGE_METADATA,
> +				      (long)-1 * (PAGE_ALIGN(table_size) >> PAGE_SHIFT));
> +

what happens with vmalloc()ed page_ext?

>  	}
>  }
>  
> diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c
> index a2cbe44c48e1..e33f302db7c6 100644
> --- a/mm/sparse-vmemmap.c
> +++ b/mm/sparse-vmemmap.c
> @@ -469,5 +469,8 @@ struct page * __meminit __populate_section_memmap(unsigned long pfn,
>  	if (r < 0)
>  		return NULL;
>  
> +	__mod_node_page_state(NODE_DATA(nid), NR_PAGE_METADATA,
> +			      PAGE_ALIGN(end - start) >> PAGE_SHIFT);
> +
>  	return pfn_to_page(pfn);
>  }
> diff --git a/mm/sparse.c b/mm/sparse.c
> index 77d91e565045..db78233a85ef 100644
> --- a/mm/sparse.c
> +++ b/mm/sparse.c
> @@ -14,7 +14,7 @@
>  #include <linux/swap.h>
>  #include <linux/swapops.h>
>  #include <linux/bootmem_info.h>
> -
> +#include <linux/vmstat.h>
>  #include "internal.h"
>  #include <asm/dma.h>
>  
> @@ -465,6 +465,9 @@ static void __init sparse_buffer_init(unsigned long size, int nid)
>  	 */
>  	sparsemap_buf = memmap_alloc(size, section_map_size(), addr, nid, true);
>  	sparsemap_buf_end = sparsemap_buf + size;
> +#ifndef CONFIG_SPARSEMEM_VMEMMAP
> +	mod_node_early_perpage_metadata(nid, PAGE_ALIGN(size) >> PAGE_SHIFT);

All early struct pages are allocated in memmap_alloc(). It'd make sense to update
the counter there.

> +#endif
>  }
>  
>  static void __init sparse_buffer_fini(void)
> @@ -641,6 +644,8 @@ static void depopulate_section_memmap(unsigned long pfn, unsigned long nr_pages,
>  	unsigned long start = (unsigned long) pfn_to_page(pfn);
>  	unsigned long end = start + nr_pages * sizeof(struct page);
>  
> +	__mod_node_page_state(NODE_DATA(page_to_nid(pfn_to_page(pfn))), NR_PAGE_METADATA,
> +			      (long)-1 * (PAGE_ALIGN(end - start) >> PAGE_SHIFT));
>  	vmemmap_free(start, end, altmap);
>  }
>  static void free_map_bootmem(struct page *memmap)
> diff --git a/mm/vmstat.c b/mm/vmstat.c
> index 00e81e99c6ee..731eb5264b49 100644
> --- a/mm/vmstat.c
> +++ b/mm/vmstat.c
> @@ -1245,6 +1245,7 @@ const char * const vmstat_text[] = {
>  	"pgpromote_success",
>  	"pgpromote_candidate",
>  #endif
> +	"nr_page_metadata",
>  
>  	/* enum writeback_stat_item counters */
>  	"nr_dirty_threshold",
> @@ -2274,4 +2275,24 @@ static int __init extfrag_debug_init(void)
>  }
>  
>  module_init(extfrag_debug_init);
> +
> +// Page metadata size (struct page and page_ext) in pages
> +unsigned long early_perpage_metadata[MAX_NUMNODES] __initdata;

static?

> +
> +void __init mod_node_early_perpage_metadata(int nid, long delta)
> +{
> +	early_perpage_metadata[nid] += delta;
> +}
> +
> +void __init writeout_early_perpage_metadata(void)
> +{
> +	int nid;
> +	struct pglist_data *pgdat;
> +
> +	for_each_online_pgdat(pgdat) {
> +		nid = pgdat->node_id;
> +		__mod_node_page_state(NODE_DATA(nid), NR_PAGE_METADATA,
> +				      early_perpage_metadata[nid]);
> +	}
> +}
>  #endif
> -- 
> 2.42.0.283.g2d96d420d3-goog
> 

-- 
Sincerely yours,
Mike.

Re: [PATCH v1 1/1] mm: report per-page metadata information

[Matthew Wilcox]

On Wed, Sep 13, 2023 at 11:51:25PM +0300, Mike Rapoport wrote:
> > @@ -387,8 +390,12 @@ static int alloc_vmemmap_page_list(unsigned long start, unsigned long end,
> >  
> >  	while (nr_pages--) {
> >  		page = alloc_pages_node(nid, gfp_mask, 0);
> > -		if (!page)
> > +		if (!page) {
> >  			goto out;
> > +		} else {
> > +			__mod_node_page_state(NODE_DATA(page_to_nid(page)),
> > +					      NR_PAGE_METADATA, 1);
> 
> We can update this once for nr_pages outside the loop, cannot we?

Except that nr_pages is being used as the loop counter.
Probably best to turn this into a normal (i = 0; i < nr_pages; i++)
loop, and then we can do as you say.  But this isn't a particularly
interesting high-performance loop.

Re: [PATCH v1 1/1] mm: report per-page metadata information

[Sourav Panda]

[-- Attachment #1: Type: text/plain, Size: 1094 bytes --]

Thank you Matthew Wilcox.

On Thu, Sep 14, 2023 at 5:48 AM Matthew Wilcox <willy@infradead.org> wrote:

> On Wed, Sep 13, 2023 at 11:51:25PM +0300, Mike Rapoport wrote:
> > > @@ -387,8 +390,12 @@ static int alloc_vmemmap_page_list(unsigned long
> start, unsigned long end,
> > >
> > >     while (nr_pages--) {
> > >             page = alloc_pages_node(nid, gfp_mask, 0);
> > > -           if (!page)
> > > +           if (!page) {
> > >                     goto out;
> > > +           } else {
> > > +                   __mod_node_page_state(NODE_DATA(page_to_nid(page)),
> > > +                                         NR_PAGE_METADATA, 1);
> >
> > We can update this once for nr_pages outside the loop, cannot we?
>
> Except that nr_pages is being used as the loop counter.
> Probably best to turn this into a normal (i = 0; i < nr_pages; i++)
> loop, and then we can do as you say.  But this isn't a particularly
> interesting high-performance loop.
>

I agree. I shall turn this into a normal (i = 0; i < nr_pages; i++) loop
and then make the relevant changes.

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Re: [PATCH v1 1/1] mm: report per-page metadata information

[Sourav Panda]

[-- Attachment #1: Type: text/plain, Size: 9140 bytes --]

Thank you Mike Rapoport for reviewing this patch series. Please find my
responses below.


>
> >  #endif /* _LINUX_VMSTAT_H */
> > diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> > index ba6d39b71cb1..ca36751be50e 100644
> > --- a/mm/hugetlb.c
> > +++ b/mm/hugetlb.c
> > @@ -1758,6 +1758,10 @@ static void
> __update_and_free_hugetlb_folio(struct hstate *h,
> >               destroy_compound_gigantic_folio(folio, huge_page_order(h));
> >               free_gigantic_folio(folio, huge_page_order(h));
> >       } else {
> > +#ifndef CONFIG_SPARSEMEM_VMEMMAP
> > +             __mod_node_page_state(NODE_DATA(page_to_nid(&folio->page)),
> > +                                   NR_PAGE_METADATA,
> -huge_page_order(h));
>
> I don't think memory map will change here with classic SPARSEMEM
>

Thank you. Yes, I agree with your comment.


>
> > +#endif
> >               __free_pages(&folio->page, huge_page_order(h));
> >       }
> >  }
> > @@ -2143,7 +2147,9 @@ static struct folio
> *alloc_buddy_hugetlb_folio(struct hstate *h,
> >               __count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
> >               return NULL;
> >       }
> > -
> > +#ifndef CONFIG_SPARSEMEM_VMEMMAP
> > +     __mod_node_page_state(NODE_DATA(nid), NR_PAGE_METADATA,
> huge_page_order(h));
> > +#endif
> >       __count_vm_event(HTLB_BUDDY_PGALLOC);
> >       return page_folio(page);
> >  }
> > diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c
> > index 4b9734777f69..7f920bfa8e79 100644
> > --- a/mm/hugetlb_vmemmap.c
> > +++ b/mm/hugetlb_vmemmap.c
> > @@ -214,6 +214,8 @@ static inline void free_vmemmap_page(struct page
> *page)
> >               free_bootmem_page(page);
> >       else
> >               __free_page(page);
> > +     __mod_node_page_state(NODE_DATA(page_to_nid(page)),
> > +                           NR_PAGE_METADATA, -1);
> >  }
> >
> >  /* Free a list of the vmemmap pages */
> > @@ -336,6 +338,7 @@ static int vmemmap_remap_free(unsigned long start,
> unsigned long end,
> >                         (void *)walk.reuse_addr);
> >               list_add(&walk.reuse_page->lru, &vmemmap_pages);
> >       }
> > +     __mod_node_page_state(NODE_DATA(nid), NR_PAGE_METADATA, 1);
> >
> >       /*
> >        * In order to make remapping routine most efficient for the huge
> pages,
> > @@ -387,8 +390,12 @@ static int alloc_vmemmap_page_list(unsigned long
> start, unsigned long end,
> >
> >       while (nr_pages--) {
> >               page = alloc_pages_node(nid, gfp_mask, 0);
> > -             if (!page)
> > +             if (!page) {
> >                       goto out;
> > +             } else {
> > +                     __mod_node_page_state(NODE_DATA(page_to_nid(page)),
> > +                                           NR_PAGE_METADATA, 1);
>
> We can update this once for nr_pages outside the loop, cannot we?
>

Thank you for the comment. I agree with you and shall incorporate it.


>
> > +             }
> >               list_add_tail(&page->lru, list);
> >       }
> >
> > diff --git a/mm/mm_init.c b/mm/mm_init.c
> > index 50f2f34745af..e02dce7e2e9a 100644
> > --- a/mm/mm_init.c
> > +++ b/mm/mm_init.c
> > @@ -26,6 +26,7 @@
> >  #include <linux/pgtable.h>
> >  #include <linux/swap.h>
> >  #include <linux/cma.h>
> > +#include <linux/vmstat.h>
> >  #include "internal.h"
> >  #include "slab.h"
> >  #include "shuffle.h"
> > @@ -1656,6 +1657,8 @@ static void __init alloc_node_mem_map(struct
> pglist_data *pgdat)
> >                       panic("Failed to allocate %ld bytes for node %d
> memory map\n",
> >                             size, pgdat->node_id);
> >               pgdat->node_mem_map = map + offset;
> > +             mod_node_early_perpage_metadata(pgdat->node_id,
> > +                                             PAGE_ALIGN(size) >>
> PAGE_SHIFT);
> >       }
> >       pr_debug("%s: node %d, pgdat %08lx, node_mem_map %08lx\n",
> >                               __func__, pgdat->node_id, (unsigned
> long)pgdat,
> > diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> > index 0c5be12f9336..4e295d5087f4 100644
> > --- a/mm/page_alloc.c
> > +++ b/mm/page_alloc.c
> > @@ -5443,6 +5443,7 @@ void __init setup_per_cpu_pageset(void)
> >       for_each_online_pgdat(pgdat)
> >               pgdat->per_cpu_nodestats =
> >                       alloc_percpu(struct per_cpu_nodestat);
> > +     writeout_early_perpage_metadata();
>
> Why it's called here?
> You can copy early stats to actual node stats as soon as the nodes and page
> allocator are initialized.
>

Thank you for mentioning this. I agree with you and shall move it there.


>
> >  }
> >
> >  __meminit void zone_pcp_init(struct zone *zone)
> > diff --git a/mm/page_ext.c b/mm/page_ext.c
> > index 4548fcc66d74..b5b9d3079e20 100644
> > --- a/mm/page_ext.c
> > +++ b/mm/page_ext.c
> > @@ -201,6 +201,8 @@ static int __init alloc_node_page_ext(int nid)
> >               return -ENOMEM;
> >       NODE_DATA(nid)->node_page_ext = base;
> >       total_usage += table_size;
> > +     __mod_node_page_state(NODE_DATA(nid), NR_PAGE_METADATA,
> > +                           PAGE_ALIGN(table_size) >> PAGE_SHIFT);
> >       return 0;
> >  }
> >
> > @@ -255,12 +257,15 @@ static void *__meminit alloc_page_ext(size_t size,
> int nid)
> >       void *addr = NULL;
> >
> >       addr = alloc_pages_exact_nid(nid, size, flags);
> > -     if (addr) {
> > +     if (addr)
> >               kmemleak_alloc(addr, size, 1, flags);
> > -             return addr;
> > -     }
> > +     else
> > +             addr = vzalloc_node(size, nid);
> >
> > -     addr = vzalloc_node(size, nid);
> > +     if (addr) {
> > +             __mod_node_page_state(NODE_DATA(nid), NR_PAGE_METADATA,
> > +                                   PAGE_ALIGN(size) >> PAGE_SHIFT);
> > +     }
> >
> >       return addr;
> >  }
> > @@ -314,6 +319,10 @@ static void free_page_ext(void *addr)
> >               BUG_ON(PageReserved(page));
> >               kmemleak_free(addr);
> >               free_pages_exact(addr, table_size);
> > +
> > +             __mod_node_page_state(NODE_DATA(page_to_nid(page)),
> NR_PAGE_METADATA,
> > +                                   (long)-1 * (PAGE_ALIGN(table_size)
> >> PAGE_SHIFT));
> > +
>
> what happens with vmalloc()ed page_ext?
>

Thank you for pointing this out. I shall also make this change for
vmalloc()ed page_ext.


>
> >       }
> >  }
> >
> > diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c
> > index a2cbe44c48e1..e33f302db7c6 100644
> > --- a/mm/sparse-vmemmap.c
> > +++ b/mm/sparse-vmemmap.c
> > @@ -469,5 +469,8 @@ struct page * __meminit
> __populate_section_memmap(unsigned long pfn,
> >       if (r < 0)
> >               return NULL;
> >
> > +     __mod_node_page_state(NODE_DATA(nid), NR_PAGE_METADATA,
> > +                           PAGE_ALIGN(end - start) >> PAGE_SHIFT);
> > +
> >       return pfn_to_page(pfn);
> >  }
> > diff --git a/mm/sparse.c b/mm/sparse.c
> > index 77d91e565045..db78233a85ef 100644
> > --- a/mm/sparse.c
> > +++ b/mm/sparse.c
> > @@ -14,7 +14,7 @@
> >  #include <linux/swap.h>
> >  #include <linux/swapops.h>
> >  #include <linux/bootmem_info.h>
> > -
> > +#include <linux/vmstat.h>
> >  #include "internal.h"
> >  #include <asm/dma.h>
> >
> > @@ -465,6 +465,9 @@ static void __init sparse_buffer_init(unsigned long
> size, int nid)
> >        */
> >       sparsemap_buf = memmap_alloc(size, section_map_size(), addr, nid,
> true);
> >       sparsemap_buf_end = sparsemap_buf + size;
> > +#ifndef CONFIG_SPARSEMEM_VMEMMAP
> > +     mod_node_early_perpage_metadata(nid, PAGE_ALIGN(size) >>
> PAGE_SHIFT);
>
> All early struct pages are allocated in memmap_alloc(). It'd make sense to
> update
> the counter there.
>

Thanks for the comment. The reason why we did not do it in memmap_alloc()
is because the struct pages can decrease as well.


>
> > +#endif
> >  }
> >
> >  static void __init sparse_buffer_fini(void)
> > @@ -641,6 +644,8 @@ static void depopulate_section_memmap(unsigned long
> pfn, unsigned long nr_pages,
> >       unsigned long start = (unsigned long) pfn_to_page(pfn);
> >       unsigned long end = start + nr_pages * sizeof(struct page);
> >
> > +     __mod_node_page_state(NODE_DATA(page_to_nid(pfn_to_page(pfn))),
> NR_PAGE_METADATA,
> > +                           (long)-1 * (PAGE_ALIGN(end - start) >>
> PAGE_SHIFT));
> >       vmemmap_free(start, end, altmap);
> >  }
> >  static void free_map_bootmem(struct page *memmap)
> > diff --git a/mm/vmstat.c b/mm/vmstat.c
> > index 00e81e99c6ee..731eb5264b49 100644
> > --- a/mm/vmstat.c
> > +++ b/mm/vmstat.c
> > @@ -1245,6 +1245,7 @@ const char * const vmstat_text[] = {
> >       "pgpromote_success",
> >       "pgpromote_candidate",
> >  #endif
> > +     "nr_page_metadata",
> >
> >       /* enum writeback_stat_item counters */
> >       "nr_dirty_threshold",
> > @@ -2274,4 +2275,24 @@ static int __init extfrag_debug_init(void)
> >  }
> >
> >  module_init(extfrag_debug_init);
> > +
> > +// Page metadata size (struct page and page_ext) in pages
> > +unsigned long early_perpage_metadata[MAX_NUMNODES] __initdata;
>
> static?
>

Thanks for pointing this out. I shall make  __initdata static in the next
version of the patch.

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Re: [PATCH v1 1/1] mm: report per-page metadata information

[kernel test robot]

Hi Sourav,

kernel test robot noticed the following build errors:

[auto build test ERROR on akpm-mm/mm-everything]
[also build test ERROR on driver-core/driver-core-testing driver-core/driver-core-next driver-core/driver-core-linus linus/master v6.6-rc1 next-20230913]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Sourav-Panda/mm-report-per-page-metadata-information/20230914-013201
base:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
patch link:    https://lore.kernel.org/r/20230913173000.4016218-2-souravpanda%40google.com
patch subject: [PATCH v1 1/1] mm: report per-page metadata information
config: um-defconfig (https://download.01.org/0day-ci/archive/20230914/202309140522.z5SLip5C-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20230914/202309140522.z5SLip5C-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202309140522.z5SLip5C-lkp@intel.com/

All errors (new ones prefixed by >>):

   /usr/bin/ld: mm/mm_init.o: in function `alloc_node_mem_map':
>> mm/mm_init.c:1660: undefined reference to `mod_node_early_perpage_metadata'
   /usr/bin/ld: mm/page_alloc.o: in function `setup_per_cpu_pageset':
>> mm/page_alloc.c:5500: undefined reference to `writeout_early_perpage_metadata'
   collect2: error: ld returned 1 exit status


vim +1660 mm/mm_init.c

  1628	
  1629	#ifdef CONFIG_FLATMEM
  1630	static void __init alloc_node_mem_map(struct pglist_data *pgdat)
  1631	{
  1632		unsigned long __maybe_unused start = 0;
  1633		unsigned long __maybe_unused offset = 0;
  1634	
  1635		/* Skip empty nodes */
  1636		if (!pgdat->node_spanned_pages)
  1637			return;
  1638	
  1639		start = pgdat->node_start_pfn & ~(MAX_ORDER_NR_PAGES - 1);
  1640		offset = pgdat->node_start_pfn - start;
  1641		/* ia64 gets its own node_mem_map, before this, without bootmem */
  1642		if (!pgdat->node_mem_map) {
  1643			unsigned long size, end;
  1644			struct page *map;
  1645	
  1646			/*
  1647			 * The zone's endpoints aren't required to be MAX_ORDER
  1648			 * aligned but the node_mem_map endpoints must be in order
  1649			 * for the buddy allocator to function correctly.
  1650			 */
  1651			end = pgdat_end_pfn(pgdat);
  1652			end = ALIGN(end, MAX_ORDER_NR_PAGES);
  1653			size =  (end - start) * sizeof(struct page);
  1654			map = memmap_alloc(size, SMP_CACHE_BYTES, MEMBLOCK_LOW_LIMIT,
  1655					   pgdat->node_id, false);
  1656			if (!map)
  1657				panic("Failed to allocate %ld bytes for node %d memory map\n",
  1658				      size, pgdat->node_id);
  1659			pgdat->node_mem_map = map + offset;
> 1660			mod_node_early_perpage_metadata(pgdat->node_id,
  1661							PAGE_ALIGN(size) >> PAGE_SHIFT);
  1662		}
  1663		pr_debug("%s: node %d, pgdat %08lx, node_mem_map %08lx\n",
  1664					__func__, pgdat->node_id, (unsigned long)pgdat,
  1665					(unsigned long)pgdat->node_mem_map);
  1666	#ifndef CONFIG_NUMA
  1667		/*
  1668		 * With no DISCONTIG, the global mem_map is just set as node 0's
  1669		 */
  1670		if (pgdat == NODE_DATA(0)) {
  1671			mem_map = NODE_DATA(0)->node_mem_map;
  1672			if (page_to_pfn(mem_map) != pgdat->node_start_pfn)
  1673				mem_map -= offset;
  1674		}
  1675	#endif
  1676	}
  1677	#else
  1678	static inline void alloc_node_mem_map(struct pglist_data *pgdat) { }
  1679	#endif /* CONFIG_FLATMEM */
  1680	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

Re: [PATCH v1 1/1] mm: report per-page metadata information

[David Hildenbrand]

On 13.09.23 19:30, Sourav Panda wrote:
> Adds a new per-node PageMetadata field to
> /sys/devices/system/node/nodeN/meminfo
> and a global PageMetadata field to /proc/meminfo. This information can
> be used by users to see how much memory is being used by per-page
> metadata, which can vary depending on build configuration, machine
> architecture, and system use.
> 
> Per-page metadata is the amount of memory that Linux needs in order to
> manage memory at the page granularity. The majority of such memory is
> used by "struct page" and "page_ext" data structures.

It's probably worth mentioning, that in contrast to most other "memory 
consumption" statistics, this metadata might not be included "MemTotal"; 
when the memmap is allocated using the memblock allocator, it's not 
included, when it's dynamically allocated using the buddy (e.g., memory 
hotplug), it's included.

-- 
Cheers,

David / dhildenb

Re: [PATCH v1 1/1] mm: report per-page metadata information

[Sourav Panda]

[-- Attachment #1: Type: text/plain, Size: 1157 bytes --]

Thank you David Hildenbrand for reviewing this patch.

On Thu, Sep 14, 2023 at 6:00 AM David Hildenbrand <david@redhat.com> wrote:

> On 13.09.23 19:30, Sourav Panda wrote:
> > Adds a new per-node PageMetadata field to
> > /sys/devices/system/node/nodeN/meminfo
> > and a global PageMetadata field to /proc/meminfo. This information can
> > be used by users to see how much memory is being used by per-page
> > metadata, which can vary depending on build configuration, machine
> > architecture, and system use.
> >
> > Per-page metadata is the amount of memory that Linux needs in order to
> > manage memory at the page granularity. The majority of such memory is
> > used by "struct page" and "page_ext" data structures.
>
> It's probably worth mentioning, that in contrast to most other "memory
> consumption" statistics, this metadata might not be included "MemTotal";
> when the memmap is allocated using the memblock allocator, it's not
> included, when it's dynamically allocated using the buddy (e.g., memory
> hotplug), it's included.
>
>
Thank you for your comment, Completely agree with you and shall make this
change.

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Re: [PATCH v1 1/1] mm: report per-page metadata information

[kernel test robot]

Hello,

kernel test robot noticed "WARNING:at_mm/vmstat.c:#__mod_node_page_state" on:

commit: af92fce0e99952613b7dac06b40a35decef4cad9 ("[PATCH v1 1/1] mm: report per-page metadata information")
url: https://github.com/intel-lab-lkp/linux/commits/Sourav-Panda/mm-report-per-page-metadata-information/20230914-013201
base: https://git.kernel.org/cgit/linux/kernel/git/akpm/mm.git mm-everything
patch link: https://lore.kernel.org/all/20230913173000.4016218-2-souravpanda@google.com/
patch subject: [PATCH v1 1/1] mm: report per-page metadata information

in testcase: boot

compiler: gcc-12
test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -smp 2 -m 16G

(please refer to attached dmesg/kmsg for entire log/backtrace)



If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <oliver.sang@intel.com>
| Closes: https://lore.kernel.org/oe-lkp/202309181546.fc42f414-oliver.sang@intel.com


[    4.596915][    T1] ------------[ cut here ]------------
[ 4.597618][ T1] WARNING: CPU: 0 PID: 1 at mm/vmstat.c:393 __mod_node_page_state (kbuild/src/rand-x86_64-2/mm/vmstat.c:393) 
[    4.598717][    T1] Modules linked in:
[    4.598835][    T1] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 6.6.0-rc1-00154-gaf92fce0e999 #4
[    4.599915][    T1] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
[ 4.601238][ T1] RIP: 0010:__mod_node_page_state (kbuild/src/rand-x86_64-2/mm/vmstat.c:393) 
[ 4.602031][ T1] Code: 5e 41 5f 5d 31 c0 31 d2 31 c9 31 f6 31 ff c3 65 8b 0d bc 7e e0 7e 81 e1 ff ff ff 7f 75 b5 65 8b 0d 11 7c c3 7e 85 c9 74 aa 90 <0f> 0b 90 eb a4 49 83 fe 29 77 26 4e 8d 3c f5 88 33 00 00 f0 4b 01
All code
========
   0:	5e                   	pop    %rsi
   1:	41 5f                	pop    %r15
   3:	5d                   	pop    %rbp
   4:	31 c0                	xor    %eax,%eax
   6:	31 d2                	xor    %edx,%edx
   8:	31 c9                	xor    %ecx,%ecx
   a:	31 f6                	xor    %esi,%esi
   c:	31 ff                	xor    %edi,%edi
   e:	c3                   	ret
   f:	65 8b 0d bc 7e e0 7e 	mov    %gs:0x7ee07ebc(%rip),%ecx        # 0x7ee07ed2
  16:	81 e1 ff ff ff 7f    	and    $0x7fffffff,%ecx
  1c:	75 b5                	jne    0xffffffffffffffd3
  1e:	65 8b 0d 11 7c c3 7e 	mov    %gs:0x7ec37c11(%rip),%ecx        # 0x7ec37c36
  25:	85 c9                	test   %ecx,%ecx
  27:	74 aa                	je     0xffffffffffffffd3
  29:	90                   	nop
  2a:*	0f 0b                	ud2		<-- trapping instruction
  2c:	90                   	nop
  2d:	eb a4                	jmp    0xffffffffffffffd3
  2f:	49 83 fe 29          	cmp    $0x29,%r14
  33:	77 26                	ja     0x5b
  35:	4e 8d 3c f5 88 33 00 	lea    0x3388(,%r14,8),%r15
  3c:	00 
  3d:	f0                   	lock
  3e:	4b                   	rex.WXB
  3f:	01                   	.byte 0x1

Code starting with the faulting instruction
===========================================
   0:	0f 0b                	ud2
   2:	90                   	nop
   3:	eb a4                	jmp    0xffffffffffffffa9
   5:	49 83 fe 29          	cmp    $0x29,%r14
   9:	77 26                	ja     0x31
   b:	4e 8d 3c f5 88 33 00 	lea    0x3388(,%r14,8),%r15
  12:	00 
  13:	f0                   	lock
  14:	4b                   	rex.WXB
  15:	01                   	.byte 0x1
[    4.602165][    T1] RSP: 0000:ffff888100307e20 EFLAGS: 00010202
[    4.602954][    T1] RAX: 00000000001f2cc0 RBX: 0000000000000000 RCX: 0000000000000001
[    4.604020][    T1] RDX: 0000000000000240 RSI: 0000000000000023 RDI: ffffffff83c6ef00
[    4.605021][    T1] RBP: ffff888100307e48 R08: 0000000000000000 R09: 0000000000000000
[    4.605499][    T1] R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff83c6ef00
[    4.606507][    T1] R13: 00000000001f2ce9 R14: 0000000000000028 R15: 0000000000240000
[    4.607520][    T1] FS:  0000000000000000(0000) GS:ffff88842fa00000(0000) knlGS:0000000000000000
[    4.608632][    T1] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[    4.608832][    T1] CR2: ffff88843ffff000 CR3: 0000000003644000 CR4: 00000000000406b0
[    4.609842][    T1] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[    4.612168][    T1] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[    4.613186][    T1] Call Trace:
[    4.613606][    T1]  <TASK>
[ 4.613982][ T1] ? show_regs (kbuild/src/rand-x86_64-2/arch/x86/kernel/dumpstack.c:479) 
[ 4.614528][ T1] ? __warn (kbuild/src/rand-x86_64-2/kernel/panic.c:677) 
[ 4.615040][ T1] ? __mod_node_page_state (kbuild/src/rand-x86_64-2/mm/vmstat.c:393) 
[ 4.615501][ T1] ? report_bug (kbuild/src/rand-x86_64-2/lib/bug.c:180 kbuild/src/rand-x86_64-2/lib/bug.c:219) 
[ 4.616083][ T1] ? handle_bug (kbuild/src/rand-x86_64-2/arch/x86/kernel/traps.c:237) 
[ 4.616642][ T1] ? exc_invalid_op (kbuild/src/rand-x86_64-2/arch/x86/kernel/traps.c:258 (discriminator 1)) 
[ 4.617240][ T1] ? asm_exc_invalid_op (kbuild/src/rand-x86_64-2/arch/x86/include/asm/idtentry.h:568) 
[ 4.617895][ T1] ? __mod_node_page_state (kbuild/src/rand-x86_64-2/mm/vmstat.c:393) 
[ 4.618575][ T1] init_section_page_ext (kbuild/src/rand-x86_64-2/mm/page_ext.c:292) 
[ 4.618836][ T1] page_ext_init (kbuild/src/rand-x86_64-2/mm/page_ext.c:482) 
[ 4.619433][ T1] page_alloc_init_late (kbuild/src/rand-x86_64-2/mm/mm_init.c:2417) 
[ 4.620098][ T1] kernel_init_freeable (kbuild/src/rand-x86_64-2/init/main.c:1325 kbuild/src/rand-x86_64-2/init/main.c:1547) 
[ 4.620765][ T1] ? rest_init (kbuild/src/rand-x86_64-2/init/main.c:1429) 
[ 4.621325][ T1] kernel_init (kbuild/src/rand-x86_64-2/init/main.c:1439) 
[ 4.621880][ T1] ? schedule_tail (kbuild/src/rand-x86_64-2/kernel/sched/core.c:5318) 
[ 4.622167][ T1] ret_from_fork (kbuild/src/rand-x86_64-2/arch/x86/kernel/process.c:153) 
[ 4.622753][ T1] ? rest_init (kbuild/src/rand-x86_64-2/init/main.c:1429) 
[ 4.623314][ T1] ret_from_fork_asm (kbuild/src/rand-x86_64-2/arch/x86/entry/entry_64.S:312) 
[    4.623942][    T1]  </TASK>
[    4.624331][    T1] irq event stamp: 11857
[ 4.624861][ T1] hardirqs last enabled at (11865): __up_console_sem (kbuild/src/rand-x86_64-2/kernel/printk/printk.c:347 (discriminator 1)) 
[ 4.625498][ T1] hardirqs last disabled at (11874): __up_console_sem (kbuild/src/rand-x86_64-2/kernel/printk/printk.c:345 (discriminator 1)) 
[ 4.626689][ T1] softirqs last enabled at (11546): __do_softirq (kbuild/src/rand-x86_64-2/arch/x86/include/asm/preempt.h:27 kbuild/src/rand-x86_64-2/kernel/softirq.c:400 kbuild/src/rand-x86_64-2/kernel/softirq.c:582) 
[ 4.627866][ T1] softirqs last disabled at (11541): __irq_exit_rcu (kbuild/src/rand-x86_64-2/kernel/softirq.c:427 kbuild/src/rand-x86_64-2/kernel/softirq.c:632) 
[    4.628832][    T1] ---[ end trace 0000000000000000 ]---
[    4.694353][    T1] allocated 301989888 bytes of page_ext



The kernel config and materials to reproduce are available at:
https://download.01.org/0day-ci/archive/20230918/202309181546.fc42f414-oliver.sang@intel.com



-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki