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From: Dmitry Monakhov <dmonakhov@openvz.org>
To: Jeremiah Mahler <jmmahler@gmail.com>,
	Stephen Rothwell <sfr@canb.auug.org.au>
Cc: linux-next@vger.kernel.org, linux-kernel@vger.kernel.org,
	"Theodore Ts'o" <tytso@mit.edu>
Subject: Re: linux-next: Tree for Dec 4
Date: Fri, 05 Dec 2014 11:29:03 +0300	[thread overview]
Message-ID: <87sigu5wkw.fsf@openvz.org> (raw)
In-Reply-To: <20141205005401.GA1279@hudson.localdomain>

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Jeremiah Mahler <jmmahler@gmail.com> writes:

> all,
>
> On Thu, Dec 04, 2014 at 03:34:11PM -0800, Jeremiah Mahler wrote:
>> all,
>> 
>> On Thu, Dec 04, 2014 at 07:59:28PM +1100, Stephen Rothwell wrote:
>> > Hi all,
>> > 
>> > Changes since 20141203:
>> > 
> [...]
>> > 
>> > -- 
>> > Cheers,
>> > Stephen Rothwell                    sfr@canb.auug.org.au
>> > 
>> [...]
>> 
>> linux-next 20141204 is broken on all my machines, 20141203 worked fine.
>> 
>> They fail very early in the boot process and are unable to mount root.
>> There are lots of "ext4_check_descriptors: Checksum for group ...
>> failed" messages.
>> 
>> Any suggestions for where to start looking?
>> 
>> -- 
>> - Jeremiah Mahler
>
> I ran a bisect and found this patch to be faulty.
>
>   commit fdfe073987619ec375da8d8a2701ab271d1b1339
>   Author: Dmitry Monakhov <dmonakhov@openvz.org>
>   Date:   Tue Dec 2 16:09:16 2014 -0500
>   
>       ext4: fix potential use after free during resize
>       
>       We need some sort of synchronization while updating ->s_group_desc
>       because there are a lot of users which can access old ->s_group_desc
>       array after it was released.
>       
>       Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
>       Signed-off-by: Theodore Ts'o <tytso@mit.edu>
+       rcu_read_lock();
+       gd_bh = *rcu_dereference(sbi->s_group_desc) + group_desc;
+       rcu_read_unlock(); 
Yes this is true crap. The only question is how it passed xfstess?

>
> -- 
> - Jeremiah Mahler

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  reply	other threads:[~2014-12-05  8:29 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-12-04  8:59 linux-next: Tree for Dec 4 Stephen Rothwell
2014-12-04 23:34 ` Jeremiah Mahler
2014-12-05  0:54   ` Jeremiah Mahler
2014-12-05  8:29     ` Dmitry Monakhov [this message]
  -- strict thread matches above, loose matches on Subject: below --
2025-12-04  6:54 Stephen Rothwell
2024-12-04 14:49 Mark Brown
2023-12-04  4:57 Stephen Rothwell
2020-12-04 10:20 Stephen Rothwell
2019-12-04  5:06 Stephen Rothwell
2018-12-04  6:46 Stephen Rothwell
2017-12-04  4:06 Stephen Rothwell
2013-12-04  3:01 Stephen Rothwell
2012-12-04  6:22 Stephen Rothwell

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