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| author | Kefeng Wang <wangkefeng.wang@huawei.com> | 2024-12-06 10:03:45 +0300 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2024-12-31 04:59:06 +0300 |
| commit | 34d7cf637c437d5c2a8a6ef23ea45193bad8a91c (patch) | |
| tree | 3284af40ee25d02f4f5d684ff88fd443136f1e97 /mm | |
| parent | 6aaced5abd32e2a57cd94fd64f824514d0361da8 (diff) | |
| download | linux-34d7cf637c437d5c2a8a6ef23ea45193bad8a91c.tar.xz | |
mm: don't try THP alignment for FS without get_unmapped_area
Commit ed48e87c7df3 ("thp: add thp_get_unmapped_area_vmflags()") changes
thp_get_unmapped_area() to thp_get_unmapped_area_vmflags() in
__get_unmapped_area(), which doesn't initialize local get_area for
anonymous mappings. This leads to us always trying THP alignment even for
file_operations which have a NULL ->get_unmapped_area() callback.
Since commit efa7df3e3bb5 ("mm: align larger anonymous mappings on THP
boundaries") we only want to enable THP alignment for anonymous mappings,
so add a !file check to avoid attempting THP alignment for file mappings.
Found issue by code inspection. THP alignment is used for easy or more
pmd mappings, from vma side. This may cause unnecessary VMA fragmentation
and potentially worse performance on filesystems that do not actually
support THPs and thus cannot benefit from the alignment.
Link: https://lkml.kernel.org/r/20241206070345.2526501-1-wangkefeng.wang@huawei.com
Fixes: ed48e87c7df3 ("thp: add thp_get_unmapped_area_vmflags()")
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Rick Edgecombe <rick.p.edgecombe@intel.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/mmap.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/mmap.c b/mm/mmap.c index 16f8e8be01f8..aec208f90337 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -892,7 +892,7 @@ __get_unmapped_area(struct file *file, unsigned long addr, unsigned long len, if (get_area) { addr = get_area(file, addr, len, pgoff, flags); - } else if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) + } else if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) && !file && !addr /* no hint */ && IS_ALIGNED(len, PMD_SIZE)) { /* Ensures that larger anonymous mappings are THP aligned. */ |