linux-kernel - Re: linux-next: slab shrinkers: BUG at mm/list

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20130617151403.GA25172@localhost.localdomain>
Date:	Mon, 17 Jun 2013 19:14:12 +0400
From:	Glauber Costa <glommer@...il.com>
To:	Michal Hocko <mhocko@...e.cz>
Cc:	Dave Chinner <david@...morbit.com>,
	Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: linux-next: slab shrinkers: BUG at mm/list_lru.c:92

On Mon, Jun 17, 2013 at 04:18:22PM +0200, Michal Hocko wrote:
> Hi,

Hi,

> I managed to trigger:
> [ 1015.776029] kernel BUG at mm/list_lru.c:92!
> [ 1015.776029] invalid opcode: 0000 [#1] SMP
> with Linux next (next-20130607) with https://lkml.org/lkml/2013/6/17/203
> on top. 
> 
> This is obviously BUG_ON(nlru->nr_items < 0) and 
> ffffffff81122d0b:       48 85 c0                test   %rax,%rax
> ffffffff81122d0e:       49 89 44 24 18          mov    %rax,0x18(%r12)
> ffffffff81122d13:       0f 84 87 00 00 00       je     ffffffff81122da0 <list_lru_walk_node+0x110>
> ffffffff81122d19:       49 83 7c 24 18 00       cmpq   $0x0,0x18(%r12)
> ffffffff81122d1f:       78 7b                   js     ffffffff81122d9c <list_lru_walk_node+0x10c>
> [...]
> ffffffff81122d9c:       0f 0b                   ud2
> 
> RAX is -1UL.
Yes, fearing those kind of imbalances, we decided to leave the counter as a signed quantity
and BUG, instead of an unsigned quantity.

> 
> I assume that the current backtrace is of no use and it would most
> probably be some shrinker which doesn't behave.
> 
There are currently 3 users of list_lru in tree: dentries, inodes and xfs.
Assuming you are not using xfs, we are left with dentries and inodes.

The first thing to do is to find which one of them is misbehaving. You can try finding
this out by the address of the list_lru, and where it lays in the superblock.

Once we know each of them is misbehaving, then we'll have to figure out why.

Any special filesystem workload ?


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/