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* [REF PATCH] mm/swap: fix swapon failure
@ 2020-11-09 11:47 Alex Shi
  2020-11-09 12:07 ` Matthew Wilcox
  0 siblings, 1 reply; 5+ messages in thread
From: Alex Shi @ 2020-11-09 11:47 UTC (permalink / raw)
  To: linmiaohe, akpm; +Cc: Darrick J. Wong, Hugh Dickins, linux-mm, linux-kernel

One of my VM guest has a swapon issue:
root #swapon -v -f /swap1
swapon /swap1
swapon: /swap1: found swap signature: version 1, page-size 4, same byte order
swapon: /swap1: pagesize=4096, swapsize=1607467008, devsize=1607467008
swapon: /swap1: swapon failed: Invalid argument

and bisection report commit 822bca52ee7e "mm/swapfile.c: fix potential
memory leak in sys_swapon" cause the trouble.

Go through the context I found the exit_swap_address_space(p->type)
shouldn't be used in good result path. So just move it to error path.

Fixes: 822bca52ee7e ("mm/swapfile.c: fix potential memory leak in
sys_swapon")
Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Andrew Morton <akpm@linux-foundation.org> 
Cc: "Darrick J. Wong" <darrick.wong@oracle.com> 
Cc: Miaohe Lin <linmiaohe@huawei.com> 
Cc: Hugh Dickins <hughd@google.com>
Cc: linux-mm@kvack.org 
Cc: linux-kernel@vger.kernel.org 
---
 mm/swapfile.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/mm/swapfile.c b/mm/swapfile.c
index c8966b8fc6ac..1ac1f737fee3 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -3339,7 +3339,8 @@ static bool swap_discardable(struct swap_info_struct *si)
 	error = inode_drain_writes(inode);
 	if (error) {
 		inode->i_flags &= ~S_SWAPFILE;
-		goto free_swap_address_space;
+		exit_swap_address_space(p->type);
+		goto bad_swap_unlock_inode;
 	}
 
 	mutex_lock(&swapon_mutex);
@@ -3364,8 +3365,6 @@ static bool swap_discardable(struct swap_info_struct *si)
 
 	error = 0;
 	goto out;
-free_swap_address_space:
-	exit_swap_address_space(p->type);
 bad_swap_unlock_inode:
 	inode_unlock(inode);
 bad_swap:
-- 
1.8.3.1



^ permalink raw reply	[flat|nested] 5+ messages in thread
* Re: [REF PATCH] mm/swap: fix swapon failure
@ 2020-11-09 12:07 linmiaohe
  0 siblings, 0 replies; 5+ messages in thread
From: linmiaohe @ 2020-11-09 12:07 UTC (permalink / raw)
  To: Alex Shi; +Cc: akpm, Darrick J. Wong, Hugh Dickins, linux-mm, linux-kernel

Hi:
Alex Shi <alex.shi@linux.alibaba.com> wrote:
> One of my VM guest has a swapon issue:
> root #swapon -v -f /swap1
> swapon /swap1
> swapon: /swap1: found swap signature: version 1, page-size 4, same byte order
> swapon: /swap1: pagesize=4096, swapsize=1607467008, devsize=1607467008
> swapon: /swap1: swapon failed: Invalid argument
>
> and bisection report commit 822bca52ee7e "mm/swapfile.c: fix potential memory leak in sys_swapon" cause the trouble.
>
> Go through the context I found the exit_swap_address_space(p->type) shouldn't be used in good result path. So just move it to error path.
>

Many thanks for your patch. But I'am somehow confused as we only do the label free_swap_address_space stuff in error path. And the good result
path can't reach here as it just goto out before free_swap_address_space label. Could you please explain it for me more detailed?

Thanks again.

> Fixes: 822bca52ee7e ("mm/swapfile.c: fix potential memory leak in
> sys_swapon")
> Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>


^ permalink raw reply	[flat|nested] 5+ messages in thread
end of thread, other threads:[~2020-11-09 12:36 UTC | newest]

Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-11-09 11:47 [REF PATCH] mm/swap: fix swapon failure Alex Shi
2020-11-09 12:07 ` Matthew Wilcox
2020-11-09 12:17   ` Alex Shi
2020-11-09 12:36     ` Alex Shi
2020-11-09 12:07 linmiaohe

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