From: Johannes Weiner <hannes@cmpxchg.org>
To: kosaki.motohiro@gmail.com
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
Minchan Kim <minchan.kim@gmail.com>,
Caspar Zhang <caspar@casparzhang.com>,
Andrew Morton <akpm@linux-foundation.org>,
Stephen Wilson <wilsons@start.ca>,
Andrea Arcangeli <aarcange@redhat.com>
Subject: Re: [PATCH] [v2] mempolicy: refix mbind_range() vma issue
Date: Tue, 20 Dec 2011 20:28:50 +0100 [thread overview]
Message-ID: <20111220192850.GB3870@cmpxchg.org> (raw)
In-Reply-To: <1324405032-22281-1-git-send-email-kosaki.motohiro@gmail.com>
On Tue, Dec 20, 2011 at 01:17:10PM -0500, kosaki.motohiro@gmail.com wrote:
> From: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
>
> commit 8aacc9f550 (mm/mempolicy.c: fix pgoff in mbind vma merge) is
> slightly incorrect fix.
>
> Why? Think following case.
>
> 1. map 4 pages of a file at offset 0
>
> [0123]
>
> 2. map 2 pages just after the first mapping of the same file but with
> page offset 2
>
> [0123][23]
>
> 3. mbind() 2 pages from the first mapping at offset 2.
> mbind_range() should treat new vma is,
>
> [0123][23]
> |23|
> mbind vma
>
> but it does
>
> [0123][23]
> |01|
> mbind vma
>
> Oops. then, it makes wrong vma merge and splitting ([01][0123] or similar).
>
> This patch fixes it.
>
> [testcase]
> test result - before the patch
>
> case4: 126: test failed. expect '2,4', actual '2,2,2'
> case5: passed
> case6: passed
> case7: passed
> case8: passed
> case_n: 246: test failed. expect '4,2', actual '1,4'
>
> ------------[ cut here ]------------
> kernel BUG at mm/filemap.c:135!
> invalid opcode: 0000 [#4] SMP DEBUG_PAGEALLOC
>
> (snip long bug on messages)
>
> test result - after the patch
>
> case4: passed
> case5: passed
> case6: passed
> case7: passed
> case8: passed
> case_n: passed
> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
> Cc: Johannes Weiner <hannes@cmpxchg.org>
> Cc: Minchan Kim <minchan.kim@gmail.com>
> CC: Caspar Zhang <caspar@casparzhang.com>
Looks good to me now, thanks.
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Since this can corrupt virtual mappings and was released with 3.2, I
think we also want this:
Cc: stable@kernel.org [3.2.x]
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WARNING: multiple messages have this Message-ID (diff)
From: Johannes Weiner <hannes@cmpxchg.org>
To: kosaki.motohiro@gmail.com
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
Minchan Kim <minchan.kim@gmail.com>,
Caspar Zhang <caspar@casparzhang.com>,
Andrew Morton <akpm@linux-foundation.org>,
Stephen Wilson <wilsons@start.ca>,
Andrea Arcangeli <aarcange@redhat.com>
Subject: Re: [PATCH] [v2] mempolicy: refix mbind_range() vma issue
Date: Tue, 20 Dec 2011 20:28:50 +0100 [thread overview]
Message-ID: <20111220192850.GB3870@cmpxchg.org> (raw)
In-Reply-To: <1324405032-22281-1-git-send-email-kosaki.motohiro@gmail.com>
On Tue, Dec 20, 2011 at 01:17:10PM -0500, kosaki.motohiro@gmail.com wrote:
> From: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
>
> commit 8aacc9f550 (mm/mempolicy.c: fix pgoff in mbind vma merge) is
> slightly incorrect fix.
>
> Why? Think following case.
>
> 1. map 4 pages of a file at offset 0
>
> [0123]
>
> 2. map 2 pages just after the first mapping of the same file but with
> page offset 2
>
> [0123][23]
>
> 3. mbind() 2 pages from the first mapping at offset 2.
> mbind_range() should treat new vma is,
>
> [0123][23]
> |23|
> mbind vma
>
> but it does
>
> [0123][23]
> |01|
> mbind vma
>
> Oops. then, it makes wrong vma merge and splitting ([01][0123] or similar).
>
> This patch fixes it.
>
> [testcase]
> test result - before the patch
>
> case4: 126: test failed. expect '2,4', actual '2,2,2'
> case5: passed
> case6: passed
> case7: passed
> case8: passed
> case_n: 246: test failed. expect '4,2', actual '1,4'
>
> ------------[ cut here ]------------
> kernel BUG at mm/filemap.c:135!
> invalid opcode: 0000 [#4] SMP DEBUG_PAGEALLOC
>
> (snip long bug on messages)
>
> test result - after the patch
>
> case4: passed
> case5: passed
> case6: passed
> case7: passed
> case8: passed
> case_n: passed
> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
> Cc: Johannes Weiner <hannes@cmpxchg.org>
> Cc: Minchan Kim <minchan.kim@gmail.com>
> CC: Caspar Zhang <caspar@casparzhang.com>
Looks good to me now, thanks.
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Since this can corrupt virtual mappings and was released with 3.2, I
think we also want this:
Cc: stable@kernel.org [3.2.x]
next prev parent reply other threads:[~2011-12-20 19:29 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-09 16:55 [PATCH] mempolicy: refix mbind_range() vma issue kosaki.motohiro
2011-12-09 16:55 ` kosaki.motohiro
2011-12-12 11:20 ` Johannes Weiner
2011-12-12 11:20 ` Johannes Weiner
2011-12-20 18:17 ` [PATCH] [v2] " kosaki.motohiro
2011-12-20 18:17 ` kosaki.motohiro
2011-12-20 19:28 ` Johannes Weiner [this message]
2011-12-20 19:28 ` Johannes Weiner
2011-12-20 23:37 ` Andrew Morton
2011-12-20 23:37 ` Andrew Morton
2011-12-20 23:54 ` Johannes Weiner
2011-12-20 23:54 ` Johannes Weiner
2011-12-20 18:19 ` [PATCH] " KOSAKI Motohiro
2011-12-20 18:19 ` KOSAKI Motohiro
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