Re: [PATCH] mm/memory-failure.c: fix memory leak by race between poison and unpoison

[Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>]

On Wed, May 14, 2014 at 03:10:37PM -0700, Andrew Morton wrote:
...
> Looking at the surrounding code...
> 
> 	/*
> 	 * Lock the page and wait for writeback to finish.
> 	 * It's very difficult to mess with pages currently under IO
> 	 * and in many cases impossible, so we just avoid it here.
> 	 */
> 	lock_page(hpage);
> 
> 
> lock_page() doesn't wait for writeback to finish -
> wait_on_page_writeback() does that.  Either the code or the comment
> could do with fixing.

OK, here is the patch to move the comment.

---
Subject: [PATCH] mm/memory-failure.c: move comment

The comment about pages under writeback is far from the relevant code,
so let's move it to the right place.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
---
 mm/memory-failure.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 93a08bd78c78..e3154d99b87f 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1132,11 +1132,6 @@ int memory_failure(unsigned long pfn, int trapno, int flags)
 		}
 	}
 
-	/*
-	 * Lock the page and wait for writeback to finish.
-	 * It's very difficult to mess with pages currently under IO
-	 * and in many cases impossible, so we just avoid it here.
-	 */
 	lock_page(hpage);
 
 	/*
@@ -1186,6 +1181,10 @@ int memory_failure(unsigned long pfn, int trapno, int flags)
 	if (PageHuge(p))
 		set_page_hwpoison_huge_page(hpage);
 
+	/*
+	 * It's very difficult to mess with pages currently under IO
+	 * and in many cases impossible, so we just avoid it here.
+	 */
 	wait_on_page_writeback(p);
 
 	/*
-- 
1.9.0

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