The quilt patch titled Subject: mm: fix for negative counter: nr_file_hugepages has been removed from the -mm tree. Its filename was mm-fix-for-negative-counter-nr_file_hugepages.patch

This patch was dropped because it was merged into the mm-hotfixes-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

------------------------------------------------------ From: Stefan Roesch shr@devkernel.io Subject: mm: fix for negative counter: nr_file_hugepages Date: Mon, 6 Nov 2023 10:19:18 -0800

While qualifiying the 6.4 release, the following warning was detected in messages:

vmstat_refresh: nr_file_hugepages -15664

The warning is caused by the incorrect updating of the NR_FILE_THPS counter in the function split_huge_page_to_list. The if case is checking for folio_test_swapbacked, but the else case is missing the check for folio_test_pmd_mappable. The other functions that manipulate the counter like __filemap_add_folio and filemap_unaccount_folio have the corresponding check.

I have a test case, which reproduces the problem. It can be found here: https://github.com/sroeschus/testcase/blob/main/vmstat_refresh/madv.c

The test case reproduces on an XFS filesystem. Running the same test case on a BTRFS filesystem does not reproduce the problem.

AFAIK version 6.1 until 6.6 are affected by this problem.

[akpm@linux-foundation.org: whitespace fix] [shr@devkernel.io: test for folio_test_pmd_mappable()] Link: https://lkml.kernel.org/r/20231108171517.2436103-1-shr@devkernel.io Link: https://lkml.kernel.org/r/20231106181918.1091043-1-shr@devkernel.io Signed-off-by: Stefan Roesch shr@devkernel.io Co-debugged-by: Johannes Weiner hannes@cmpxchg.org Acked-by: Johannes Weiner hannes@cmpxchg.org Reviewed-by: Matthew Wilcox (Oracle) willy@infradead.org Reviewed-by: David Hildenbrand david@redhat.com Reviewed-by: Yang Shi shy828301@gmail.com Cc: Rik van Riel riel@surriel.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

mm/huge_memory.c | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-)

--- a/mm/huge_memory.c~mm-fix-for-negative-counter-nr_file_hugepages +++ a/mm/huge_memory.c @@ -2769,13 +2769,15 @@ int split_huge_page_to_list(struct page int nr = folio_nr_pages(folio);

xas_split(&xas, folio, folio_order(folio)); - if (folio_test_swapbacked(folio)) { - __lruvec_stat_mod_folio(folio, NR_SHMEM_THPS, - -nr); - } else { - __lruvec_stat_mod_folio(folio, NR_FILE_THPS, - -nr); - filemap_nr_thps_dec(mapping); + if (folio_test_pmd_mappable(folio)) { + if (folio_test_swapbacked(folio)) { + __lruvec_stat_mod_folio(folio, + NR_SHMEM_THPS, -nr); + } else { + __lruvec_stat_mod_folio(folio, + NR_FILE_THPS, -nr); + filemap_nr_thps_dec(mapping); + } } }

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Patches currently in -mm which might be from shr@devkernel.io are