Commit 52b52bf1 authored by Yang Shi's avatar Yang Shi Committed by Andrew Morton
Browse files

mm: khugepaged: skip DAX vma 

The DAX vma may be seen by khugepaged when the mm has other khugepaged
suitable vmas.  So khugepaged may try to collapse THP for DAX vma, but it
will fail due to page sanity check, for example, page is not on LRU.

So it is not harmful, but it is definitely pointless to run khugepaged
against DAX vma, so skip it in early check.

Link: https://lkml.kernel.org/r/20220510203222.24246-4-shy828301@gmail.com


Signed-off-by: default avatarYang Shi <shy828301@gmail.com>
Reviewed-by: default avatarMiaohe Lin <linmiaohe@huawei.com>
Acked-by: default avatarSong Liu <song@kernel.org>
Acked-by: default avatarVlastmil Babka <vbabka@suse.cz>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent cb648754

mm/khugepaged.c

+4 −0
Original line number Diff line number Diff line
@@ -447,6 +447,10 @@ static bool hugepage_vma_check(struct vm_area_struct *vma, 
	if (vm_flags & VM_NO_KHUGEPAGED)

		return false;



	/* Don't run khugepaged against DAX vma */

	if (vma_is_dax(vma))

		return false;



	if (vma->vm_file && !IS_ALIGNED((vma->vm_start >> PAGE_SHIFT) -

				vma->vm_pgoff, HPAGE_PMD_NR))

		return false;