From: Dave Chinner <david@fromorbit.com>
To: NeilBrown <neilb@suse.de>
Cc: Jeff Layton <jlayton@redhat.com>,
linux-nfs@vger.kernel.org, Peter Zijlstra <peterz@infradead.org>,
netdev@vger.kernel.org, Ming Lei <ming.lei@canonical.com>,
linux-kernel@vger.kernel.org, xfs@oss.sgi.com,
linux-mm@kvack.org, Ingo Molnar <mingo@redhat.com>
Subject: Re: [PATCH/RFC 00/19] Support loop-back NFS mounts
Date: Thu, 17 Apr 2014 11:27:39 +1000 [thread overview]
Message-ID: <20140417012739.GU15995@dastard> (raw)
In-Reply-To: <20140417102048.2fc8275c@notabene.brown>
On Thu, Apr 17, 2014 at 10:20:48AM +1000, NeilBrown wrote:
> A good example is the deadlock with the flush-* threads.
> flush-* will lock a page, and then call ->writepage. If ->writepage
> allocates memory it can enter reclaim, call ->releasepage on NFS, and block
> waiting for a COMMIT to complete.
> The COMMIT might already be running, performing fsync on that same file that
> flush-* is flushing. It locks each page in turn. When it gets to the page
> that flush-* has locked, it will deadlock.
It's nfs_release_page() again....
> In general, if nfsd is allowed to block on local filesystem, and local
> filesystem is allowed to block on NFS, then a deadlock can happen.
> We would need a clear hierarchy
>
> __GFP_NETFS > __GFP_FS > __GFP_IO
>
> for it to work. I'm not sure the extra level really helps a lot and it would
> be a lot of churn.
I think you are looking at this the wrong way - it's not the other
filesystems that have to avoid memory reclaim recursion, it's the
NFS client mount that is on loopback that needs to avoid recursion.
IMO, the fix should be that the NFS client cannot block on messages sent to the NFSD
on the same host during memory reclaim. That is, nfs_release_page()
cannot send commit messages to the server if the server is on
localhost. Instead, it just tells memory reclaim that it can't
reclaim that page.
If nfs_release_page() no longer blocks in memory reclaim, and all
these nfsd-gets-blocked-in-GFP_KERNEL-memory-allocation recursion
problems go away. Do the same for all the other memory reclaim
operations in the NFS client, and you've got a solution that should
work without needing to walk all over the rest of the kernel....
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2014-04-17 1:27 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-04-16 4:03 NeilBrown
2014-04-16 4:03 ` [PATCH 04/19] Make effect of PF_FSTRANS to disable __GFP_FS universal NeilBrown
2014-04-16 5:37 ` Dave Chinner
2014-04-16 6:17 ` NeilBrown
2014-04-17 1:03 ` NeilBrown
2014-04-17 4:41 ` Dave Chinner
2014-04-16 4:03 ` [PATCH 05/19] SUNRPC: track whether a request is coming from a loop-back interface NeilBrown
2014-04-16 14:47 ` Jeff Layton
2014-04-16 23:25 ` NeilBrown
2014-04-16 4:03 ` [PATCH 03/19] lockdep: improve scenario messages for RECLAIM_FS errors NeilBrown
2014-04-16 7:22 ` Peter Zijlstra
2014-04-16 4:03 ` [PATCH 08/19] Set PF_FSTRANS while write_cache_pages calls ->writepage NeilBrown
2014-04-16 4:03 ` [PATCH 06/19] nfsd: set PF_FSTRANS for nfsd threads NeilBrown
2014-04-16 7:28 ` Peter Zijlstra
2014-04-16 4:03 ` [PATCH 12/19] NET: set PF_FSTRANS while holding rtnl_lock NeilBrown
2014-04-16 4:03 ` [PATCH 01/19] Promote current_{set, restore}_flags_nested from xfs to global NeilBrown
2014-04-16 4:03 ` [PATCH 14/19] driver core: set PF_FSTRANS while holding gdp_mutex NeilBrown
2014-04-16 4:03 ` [PATCH 11/19] FS: set PF_FSTRANS while holding mmap_sem in exec.c NeilBrown
2014-04-16 4:03 ` [PATCH 10/19] NET: set PF_FSTRANS while holding sk_lock NeilBrown
2014-04-16 5:13 ` Eric Dumazet
2014-04-16 5:47 ` NeilBrown
2014-04-16 13:00 ` David Miller
2014-04-17 2:38 ` NeilBrown
2014-04-16 4:03 ` [PATCH 13/19] MM: set PF_FSTRANS while allocating per-cpu memory to avoid deadlock NeilBrown
2014-04-16 5:49 ` Dave Chinner
2014-04-16 6:22 ` NeilBrown
2014-04-16 6:30 ` Dave Chinner
2014-04-16 4:03 ` [PATCH 02/19] lockdep: lockdep_set_current_reclaim_state should save old value NeilBrown
2014-04-16 4:03 ` [PATCH 09/19] XFS: ensure xfs_file_*_read cannot deadlock in memory allocation NeilBrown
2014-04-16 6:04 ` Dave Chinner
2014-04-16 6:27 ` NeilBrown
2014-04-16 6:31 ` Dave Chinner
2014-04-16 4:03 ` [PATCH 07/19] nfsd and VM: use PF_LESS_THROTTLE to avoid throttle in shrink_inactive_list NeilBrown
2014-04-16 4:03 ` [PATCH 16/19] VFS: use GFP_NOFS rather than GFP_KERNEL in __d_alloc NeilBrown
2014-04-16 6:25 ` Dave Chinner
2014-04-16 6:49 ` NeilBrown
2014-04-16 9:00 ` Dave Chinner
2014-04-17 0:51 ` NeilBrown
2014-04-17 5:58 ` Dave Chinner
2014-04-16 4:03 ` [PATCH 19/19] XFS: set PF_FSTRANS while ilock is held in xfs_free_eofblocks NeilBrown
2014-04-16 6:18 ` Dave Chinner
2014-04-16 4:03 ` [PATCH 17/19] VFS: set PF_FSTRANS while namespace_sem is held NeilBrown
2014-04-16 4:46 ` Al Viro
2014-04-16 5:52 ` NeilBrown
[not found] ` <20140416155230.4d02e4b9-wvvUuzkyo1EYVZTmpyfIwg@public.gmane.org>
2014-04-16 16:37 ` Al Viro
2014-04-16 4:03 ` [PATCH 15/19] nfsd: set PF_FSTRANS when client_mutex " NeilBrown
2014-04-16 4:03 ` [PATCH 18/19] nfsd: set PF_FSTRANS during nfsd4_do_callback_rpc NeilBrown
2014-04-16 14:42 ` [PATCH/RFC 00/19] Support loop-back NFS mounts Jeff Layton
2014-04-17 0:20 ` NeilBrown
2014-04-17 1:27 ` Dave Chinner [this message]
2014-04-17 1:50 ` NeilBrown
2014-04-17 4:23 ` Dave Chinner
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20140417012739.GU15995@dastard \
--to=david@fromorbit.com \
--cc=jlayton@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=linux-nfs@vger.kernel.org \
--cc=ming.lei@canonical.com \
--cc=mingo@redhat.com \
--cc=neilb@suse.de \
--cc=netdev@vger.kernel.org \
--cc=peterz@infradead.org \
--cc=xfs@oss.sgi.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox