linux-kernel - Re: [PATCH 19/19] XFS: set PF_FSTRANS while ilock is held in xfs_free

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: Windows password security audit tool. GUI, reports in PDF.

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

Message-ID: <20140416061819.GF15995@dastard>
Date:	Wed, 16 Apr 2014 16:18:20 +1000
From:	Dave Chinner <david@...morbit.com>
To:	NeilBrown <neilb@...e.de>
Cc:	linux-mm@...ck.org, linux-nfs@...r.kernel.org,
	linux-kernel@...r.kernel.org, xfs@....sgi.com
Subject: Re: [PATCH 19/19] XFS: set PF_FSTRANS while ilock is held in
 xfs_free_eofblocks

On Wed, Apr 16, 2014 at 02:03:37PM +1000, NeilBrown wrote:
> memory allocates can happen while the xfs ilock is held in
> xfs_free_eofblocks, particularly
> 
>   [<ffffffff813e6667>] kmem_zone_alloc+0x67/0xc0
>   [<ffffffff813e5945>] xfs_trans_add_item+0x25/0x50
>   [<ffffffff8143d64c>] xfs_trans_ijoin+0x2c/0x60
>   [<ffffffff8142275e>] xfs_itruncate_extents+0xbe/0x400
>   [<ffffffff813c72f4>] xfs_free_eofblocks+0x1c4/0x240
> 
> So set PF_FSTRANS to avoid this causing a deadlock.

Another "You broke KM_NOFS" moment. You win a Kit Kat. ;)

xfs_trans_add_item():

	lidp = kmem_zone_zalloc(xfs_log_item_desc_zone, KM_SLEEP | KM_NOFS);

KM_NOFS needs to work, otherwise XFS is just a huge steaming pile of
memory reclaim deadlocks regardless of whether you are using
loopback NFS or not.

Cheers,

Dave.
-- 
Dave Chinner
david@...morbit.com
--
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/