The quilt patch titled
Subject: mm: don't try THP alignment for FS without get_unmapped_area
has been removed from the -mm tree. Its filename was
mm-dont-try-thp-align-for-fs-without-get_unmapped_area.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: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
Subject: mm: don't try THP alignment for FS without get_unmapped_area
Date: Fri, 6 Dec 2024 15:03:45 +0800
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@xxxxxxxxxx
Fixes: ed48e87c7df3 ("thp: add thp_get_unmapped_area_vmflags()")
Signed-off-by: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
Reviewed-by: Vlastimil Babka <vbabka@xxxxxxx>
Reviewed-by: Yang Shi <shy828301@xxxxxxxxx>
Cc: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Jann Horn <jannh@xxxxxxxxxx>
Cc: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
Cc: Lorenzo Stoakes <lorenzo.stoakes@xxxxxxxxxx>
Cc: Rick Edgecombe <rick.p.edgecombe@xxxxxxxxx>
Cc: Ryan Roberts <ryan.roberts@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/mmap.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/mmap.c~mm-dont-try-thp-align-for-fs-without-get_unmapped_area
+++ a/mm/mmap.c
@@ -892,7 +892,7 @@ __get_unmapped_area(struct file *file, u
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. */
_
Patches currently in -mm which might be from wangkefeng.wang@xxxxxxxxxx are
