From: Yang Shi <shy828301@gmail.com>
To: vbabka@suse.cz, kirill.shutemov@linux.intel.com,
willy@infradead.org, zokeefe@google.com, linmiaohe@huawei.com,
akpm@linux-foundation.org
Cc: shy828301@gmail.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: [v4 PATCH 3/7] mm: khugepaged: better comments for anon vma check in hugepage_vma_revalidate
Date: Wed, 15 Jun 2022 10:29:22 -0700 [thread overview]
Message-ID: <20220615172926.546974-4-shy828301@gmail.com> (raw)
In-Reply-To: <20220615172926.546974-1-shy828301@gmail.com>
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.
Signed-off-by: Yang Shi <shy828301@gmail.com>
---
mm/khugepaged.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index db0b334a7d1f..5baa394e34c8 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -960,7 +960,13 @@ 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;
--
2.26.3
next prev parent reply other threads:[~2022-06-15 17:29 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-15 17:29 [mm-unstable v4 PATCH 0/7] Cleanup transhuge_xxx helpers Yang Shi
2022-06-15 17:29 ` [v4 PATCH 1/7] mm: khugepaged: check THP flag in hugepage_vma_check() Yang Shi
2022-06-15 17:29 ` [v4 PATCH 2/7] mm: thp: consolidate vma size check to transhuge_vma_suitable Yang Shi
2022-06-15 23:55 ` Zach O'Keefe
2022-06-15 17:29 ` Yang Shi [this message]
2022-06-15 23:57 ` [v4 PATCH 3/7] mm: khugepaged: better comments for anon vma check in hugepage_vma_revalidate Zach O'Keefe
2022-06-15 17:29 ` [v4 PATCH 4/7] mm: thp: kill transparent_hugepage_active() Yang Shi
2022-06-16 0:17 ` Zach O'Keefe
2022-06-16 0:32 ` Yang Shi
2022-06-15 17:29 ` [v4 PATCH 5/7] mm: thp: kill __transhuge_page_enabled() Yang Shi
2022-06-16 0:56 ` Zach O'Keefe
2022-06-15 17:29 ` [v4 PATCH 6/7] mm: khugepaged: reorg some khugepaged helpers Yang Shi
2022-06-16 0:27 ` Zach O'Keefe
2022-06-15 17:29 ` [v4 PATCH 7/7] doc: proc: fix the description to THPeligible Yang Shi
2022-06-16 0:20 ` Zach O'Keefe
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