The patch titled
Subject: mm: update the memmap stat before page is freed
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
mm-update-the-memmap-stat-before-page-is-freed.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-update-the-memmap-stat-before-page-is-freed.patch
This patch will later appear in the mm-hotfixes-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Pasha Tatashin <pasha.tatashin@xxxxxxxxxx>
Subject: mm: update the memmap stat before page is freed
Date: Wed, 7 Aug 2024 21:19:27 +0000
Patch series "Fixes for memmap accounting", v2.
Memmap accounting provides us with observability of how much memory is
used for per-page metadata: i.e. "struct page"'s and "struct page_ext".
It also provides with information of how much was allocated using boot
allocator (i.e. not part of MemTotal), and how much was allocated using
buddy allocated (i.e. part of MemTotal).
This small series fixes a few problems that were discovered with the
original patch which added the accounting of per-page metadata.
This patch (of 3):
It is more logical to update the stat before the page is freed, to avoid
use after free scenarios.
Link: https://lkml.kernel.org/r/20240807211929.3433304-1-pasha.tatashin@xxxxxxxxxx
Link: https://lkml.kernel.org/r/20240807211929.3433304-2-pasha.tatashin@xxxxxxxxxx
Fixes: 15995a352474 ("mm: report per-page metadata information")
Signed-off-by: Pasha Tatashin <pasha.tatashin@xxxxxxxxxx>
Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
Cc: Alison Schofield <alison.schofield@xxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Domenico Cerasuolo <cerasuolodomenico@xxxxxxxxx>
Cc: Joel Granados <j.granados@xxxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Li Zhijian <lizhijian@xxxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Mike Rapoport <rppt@xxxxxxxxxx>
Cc: Muchun Song <muchun.song@xxxxxxxxx>
Cc: Nhat Pham <nphamcs@xxxxxxxxx>
Cc: Sourav Panda <souravpanda@xxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Yi Zhang <yi.zhang@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/hugetlb_vmemmap.c | 4 ++--
mm/page_ext.c | 8 ++++----
2 files changed, 6 insertions(+), 6 deletions(-)
--- a/mm/hugetlb_vmemmap.c~mm-update-the-memmap-stat-before-page-is-freed
+++ a/mm/hugetlb_vmemmap.c
@@ -185,11 +185,11 @@ static int vmemmap_remap_range(unsigned
static inline void free_vmemmap_page(struct page *page)
{
if (PageReserved(page)) {
- free_bootmem_page(page);
mod_node_page_state(page_pgdat(page), NR_MEMMAP_BOOT, -1);
+ free_bootmem_page(page);
} else {
- __free_page(page);
mod_node_page_state(page_pgdat(page), NR_MEMMAP, -1);
+ __free_page(page);
}
}
--- a/mm/page_ext.c~mm-update-the-memmap-stat-before-page-is-freed
+++ a/mm/page_ext.c
@@ -330,18 +330,18 @@ static void free_page_ext(void *addr)
if (is_vmalloc_addr(addr)) {
page = vmalloc_to_page(addr);
pgdat = page_pgdat(page);
+ mod_node_page_state(pgdat, NR_MEMMAP,
+ -1L * (DIV_ROUND_UP(table_size, PAGE_SIZE)));
vfree(addr);
} else {
page = virt_to_page(addr);
pgdat = page_pgdat(page);
+ mod_node_page_state(pgdat, NR_MEMMAP,
+ -1L * (DIV_ROUND_UP(table_size, PAGE_SIZE)));
BUG_ON(PageReserved(page));
kmemleak_free(addr);
free_pages_exact(addr, table_size);
}
-
- mod_node_page_state(pgdat, NR_MEMMAP,
- -1L * (DIV_ROUND_UP(table_size, PAGE_SIZE)));
-
}
static void __free_page_ext(unsigned long pfn)
_
Patches currently in -mm which might be from pasha.tatashin@xxxxxxxxxx are
mm-update-the-memmap-stat-before-page-is-freed.patch
mm-dont-account-memmap-on-failure.patch
mm-dont-account-memmap-per-node.patch
memcg-increase-the-valid-index-range-for-memcg-stats-v5.patch
vmstat-kernel-stack-usage-histogram.patch
task_stack-uninline-stack_not_used.patch
