[PATCH] mm: remove unnecessary WARN_ONCE in page_vma_mapped_walk().

[Zi Yan]

From: Zi Yan 

A non present pmd entry can appear after pmd_lock is taken in
page_vma_mapped_walk(), even if THP migration is not enabled.
The WARN_ONCE is unnecessary.

Fixes: 616b8371539a ("mm: thp: enable thp migration in generic path")
Reported-and-tested-by: Abdul Haleem 
Signed-off-by: Zi Yan 
Cc: "Kirill A. Shutemov" 
Cc: Anshuman Khandual 
Cc: Andrew Morton 
---
 mm/page_vma_mapped.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c
index 6a03946469a9..eb462e7db0a9 100644
--- a/mm/page_vma_mapped.c
+++ b/mm/page_vma_mapped.c
@@ -167,8 +167,7 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw)
return not_found(pvmw);
return true;
}
-   } else
-   WARN_ONCE(1, "Non present huge pmd without pmd 
migration enabled!");
+   }
return not_found(pvmw);
} else {
/* THP pmd was split under us: handle on pte level */
-- 
2.14.1

Re: [PATCH] mm: remove unnecessary WARN_ONCE in page_vma_mapped_walk().

[Kirill A. Shutemov]

On Tue, Oct 03, 2017 at 10:26:06AM -0400, Zi Yan wrote:
> From: Zi Yan 
> 
> A non present pmd entry can appear after pmd_lock is taken in
> page_vma_mapped_walk(), even if THP migration is not enabled.
> The WARN_ONCE is unnecessary.
> 
> Fixes: 616b8371539a ("mm: thp: enable thp migration in generic path")
> Reported-and-tested-by: Abdul Haleem 
> Signed-off-by: Zi Yan 
> Cc: "Kirill A. Shutemov" 
> Cc: Anshuman Khandual 
> Cc: Andrew Morton 

Acked-by: Kirill A. Shutemov 

-- 
 Kirill A. Shutemov