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| author | Baolin Wang <baolin.wang@linux.alibaba.com> | 2026-09-14 10:12:41 +0800 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2026-09-13 21:30:13 -0700 |
| commit | 1538a25f38cf1940efeacd2a9ad7ba8d9e005769 (patch) | |
| tree | 32001767891353928075bf686474ce22df2f81f9 | |
| parent | 1be399d378b781f0ec87d3028c175815d6294b7f (diff) | |
| download | linux-next-1538a25f38cf1940efeacd2a9ad7ba8d9e005769.tar.gz linux-next-1538a25f38cf1940efeacd2a9ad7ba8d9e005769.zip | |
mm: shmem: ignore sysfs configs for shmem forced collapse
According to Documentation/mm/transhuge.rst, MADV_COLLAPSE is expected to
ignore any THP or mTHP interface settings.
However, after commit 26c7d8413aaf ("mm: thp: support "THPeligible"
semantics for mTHP with anonymous shmem"), performing MADV_COLLAPSE on
shmem will depend on /sys/.../hugepages-2048kB/shmem_enabled being set to
"inherit" (although that is the default), which can cause MADV_COLLAPSE to
fail unexpectedly.
This could cause a userspace-visible performance regression.
Fix this by returning the result of shmem_huge_global_enabled() directly
when MADV_COLLAPSE is requested, allowing PMD-order collapse while
ignoring shmem THP/mTHP settings.
Link: https://lore.kernel.org/063f655b4d6c4234f3aa27ed6ecab10283ecb880.1789351825.git.baolin.wang@linux.alibaba.com
Fixes: 26c7d8413aaf ("mm: thp: support "THPeligible" semantics for mTHP with anonymous shmem")
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reported-by: Kiryl Shutsemau (Meta) <kas@kernel.org>
Closes: https://lore.kernel.org/all/20260908125105.1510704-7-kirill@shutemov.name/
Reviewed-by: Kiryl Shutsemau (Meta) <kas@kernel.org>
Acked-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Lance Yang <lance.yang@linux.dev>
Reviewed-by: Barry Song <baohua@kernel.org>
Acked-by: Qi Zheng <qi.zheng@linux.dev>
Cc: David Hildenbrand <david@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: <stable@vger.kernel.org>
| -rw-r--r-- | mm/shmem.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/mm/shmem.c b/mm/shmem.c index de144a9a9558..c6be59619562 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -1847,8 +1847,11 @@ unsigned long shmem_allowable_huge_orders(struct inode *inode, global_orders = shmem_huge_global_enabled(inode, index, write_end, shmem_huge_force, vma, vm_flags); - /* Tmpfs huge pages allocation */ - if (!vma || !vma_is_anon_shmem(vma)) + /* + * Tmpfs huge pages allocation or forced collapse ignores + * sysfs configs. + */ + if (!vma || !vma_is_anon_shmem(vma) || shmem_huge_force) return global_orders; /* |