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| author |   Yang Shi <shy828301@gmail.com> | 2022-06-16 10:48:36 -0700 |
|---|---|---|
| committer |   akpm <akpm@linux-foundation.org> | 2022-07-17 17:14:32 -0700 |
| commit | f707fa493784b515ced01d4e261afe16fc784b5d (patch) | |
| tree | c036943c7d9f40adefdd2bb24b766a08d1190884 /mm/khugepaged.c | |
| parent | mm: thp: consolidate vma size check to transhuge_vma_suitable (diff) | |
| download | linux-dev-f707fa493784b515ced01d4e261afe16fc784b5d.tar.xz linux-dev-f707fa493784b515ced01d4e261afe16fc784b5d.zip | |
mm: khugepaged: better comments for anon vma check in hugepage_vma_revalidate
The hugepage_vma_revalidate() needs to check if the vma is still anonymous
vma or not since the address may be unmapped then remapped to file before
khugepaged reaquired the mmap_lock.
The old comment is not quite helpful, elaborate this with better comment.
Link: https://lkml.kernel.org/r/20220616174840.1202070-4-shy828301@gmail.com
Signed-off-by: Yang Shi <shy828301@gmail.com>
Reviewed-by: Zach O'Keefe <zokeefe@google.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/khugepaged.c')
| -rw-r--r-- | mm/khugepaged.c | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/mm/khugepaged.c b/mm/khugepaged.c index c7e22135f1b5..67e144e64b7f 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -958,7 +958,13 @@ static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address, return SCAN_ADDRESS_RANGE; if (!hugepage_vma_check(vma, vma->vm_flags)) return SCAN_VMA_CHECK; - /* Anon VMA expected */ + /* + * Anon VMA expected, the address may be unmapped then + * remapped to file after khugepaged reaquired the mmap_lock. + * + * hugepage_vma_check may return true for qualified file + * vmas. + */ if (!vma->anon_vma || !vma_is_anonymous(vma)) return SCAN_VMA_CHECK; return 0; |