linux-kernel - [v4 PATCH 1/7] mm: khugepaged: check THP flag in hugepage_vma

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Message-Id: <20220615172926.546974-2-shy828301@gmail.com>
Date:   Wed, 15 Jun 2022 10:29:20 -0700
From:   Yang Shi <shy828301@...il.com>
To:     vbabka@...e.cz, kirill.shutemov@...ux.intel.com,
        willy@...radead.org, zokeefe@...gle.com, linmiaohe@...wei.com,
        akpm@...ux-foundation.org
Cc:     shy828301@...il.com, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: [v4 PATCH 1/7] mm: khugepaged: check THP flag in hugepage_vma_check()

Currently the THP flag check in hugepage_vma_check() will fallthrough if
the flag is NEVER and VM_HUGEPAGE is set.  This is not a problem for now
since all the callers have the flag checked before or can't be invoked if
the flag is NEVER.

However, the following patch will call hugepage_vma_check() in more
places, for example, page fault, so this flag must be checked in
hugepge_vma_check().

Reviewed-by: Zach O'Keefe <zokeefe@...gle.com>
Reviewed-by: Miaohe Lin <linmiaohe@...wei.com>
Signed-off-by: Yang Shi <shy828301@...il.com>
---
 mm/khugepaged.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 476d79360101..b1dab94c0f1e 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -458,6 +458,9 @@ bool hugepage_vma_check(struct vm_area_struct *vma,
 	if (shmem_file(vma->vm_file))
 		return shmem_huge_enabled(vma);
 
+	if (!khugepaged_enabled())
+		return false;
+
 	/* THP settings require madvise. */
 	if (!(vm_flags & VM_HUGEPAGE) && !khugepaged_always())
 		return false;
-- 
2.26.3