From: "Theodore Ts'o" <tytso@mit.edu>
To: Michal Hocko <mhocko@kernel.org>
Cc: Jan Kara <jack@suse.cz>,
linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
Dave Chinner <david@fromorbit.com>,
djwong@kernel.org, Chris Mason <clm@fb.com>,
David Sterba <dsterba@suse.cz>,
ceph-devel@vger.kernel.org, cluster-devel@redhat.com,
linux-nfs@vger.kernel.org, logfs@logfs.org,
linux-xfs@vger.kernel.org, linux-ext4@vger.kernel.org,
linux-btrfs@vger.kernel.org, linux-mtd@lists.infradead.org,
reiserfs-devel@vger.kernel.org,
linux-ntfs-dev@lists.sourceforge.net,
linux-f2fs-devel@lists.sourceforge.net,
linux-afs@lists.infradead.org,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 8/8] Revert "ext4: fix wrong gfp type under transaction"
Date: Fri, 27 Jan 2017 01:13:18 -0500 [thread overview]
Message-ID: <20170127061318.xd2qxashbl4dajez@thunk.org> (raw)
In-Reply-To: <20170126074455.GC8456@dhcp22.suse.cz>
On Thu, Jan 26, 2017 at 08:44:55AM +0100, Michal Hocko wrote:
> > > I'm convinced the current series is OK, only real life will tell us whether
> > > we missed something or not ;)
> >
> > I would like to extend the changelog of "jbd2: mark the transaction
> > context with the scope GFP_NOFS context".
> >
> > "
> > Please note that setups without journal do not suffer from potential
> > recursion problems and so they do not need the scope protection because
> > neither ->releasepage nor ->evict_inode (which are the only fs entry
> > points from the direct reclaim) can reenter a locked context which is
> > doing the allocation currently.
> > "
>
> Could you comment on this Ted, please?
I guess.... so there still is one way this could screw us, and it's this reason for GFP_NOFS:
- to prevent from stack overflows during the reclaim because
the allocation is performed from a deep context already
The writepages call stack can be pretty deep. (Especially if we're
using ext4 in no journal mode over, say, iSCSI.)
How much stack space can get consumed by a reclaim?
- Ted
next prev parent reply other threads:[~2017-01-27 6:13 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-06 14:10 [PATCH 0/8 v3] scope GFP_NOFS api Michal Hocko
2017-01-06 14:11 ` [PATCH 1/8] lockdep: allow to disable reclaim lockup detection Michal Hocko
2017-01-09 12:56 ` Vlastimil Babka
2017-01-06 14:11 ` [PATCH 2/8] xfs: abstract PF_FSTRANS to PF_MEMALLOC_NOFS Michal Hocko
2017-01-09 12:59 ` Vlastimil Babka
2017-01-09 14:29 ` Michal Hocko
2017-01-09 20:58 ` Darrick J. Wong
2017-01-06 14:11 ` [PATCH 3/8] mm: introduce memalloc_nofs_{save,restore} API Michal Hocko
2017-01-09 13:04 ` Vlastimil Babka
2017-01-09 13:42 ` Michal Hocko
2017-01-09 13:59 ` Michal Hocko
2017-01-09 14:04 ` Vlastimil Babka
2017-01-06 14:11 ` [PATCH 4/8] xfs: use memalloc_nofs_{save,restore} instead of memalloc_noio* Michal Hocko
2017-01-09 14:08 ` Vlastimil Babka
2017-01-09 14:25 ` Michal Hocko
2017-01-09 15:56 ` Brian Foster
2017-01-09 20:59 ` Darrick J. Wong
2017-01-06 14:11 ` [PATCH 5/8] jbd2: mark the transaction context with the scope GFP_NOFS context Michal Hocko
2017-01-06 14:11 ` [PATCH 6/8] jbd2: make the whole kjournald2 kthread NOFS safe Michal Hocko
2017-01-06 14:11 ` [PATCH 7/8] Revert "ext4: avoid deadlocks in the writeback path by using sb_getblk_gfp" Michal Hocko
2017-01-17 3:01 ` Theodore Ts'o
2017-01-17 7:54 ` Michal Hocko
2017-03-06 11:59 ` Michal Hocko
2017-01-06 14:11 ` [PATCH 8/8] Revert "ext4: fix wrong gfp type under transaction" Michal Hocko
2017-01-17 2:56 ` Theodore Ts'o
2017-01-17 8:24 ` Michal Hocko
2017-01-17 15:18 ` Michal Hocko
2017-01-17 15:59 ` Theodore Ts'o
2017-01-17 16:16 ` Michal Hocko
2017-01-17 17:29 ` Jan Kara
2017-01-19 8:39 ` Michal Hocko
2017-01-19 9:22 ` Jan Kara
2017-01-19 9:44 ` Michal Hocko
2017-01-26 7:44 ` Michal Hocko
2017-01-27 6:13 ` Theodore Ts'o [this message]
2017-01-27 9:37 ` Michal Hocko
2017-01-27 16:40 ` Theodore Ts'o
2017-01-28 7:32 ` [Cluster-devel] " Christoph Hellwig
2017-01-28 8:17 ` David Lang
2017-01-30 8:12 ` Michal Hocko
2017-02-03 15:32 ` Michal Hocko
2017-01-17 21:04 ` Andreas Dilger
2017-01-18 8:29 ` Michal Hocko
2017-01-06 14:18 ` [DEBUG PATCH 0/2] debug explicit GFP_NO{FS,IO} usage from the scope context Michal Hocko
2017-01-06 14:18 ` [DEBUG PATCH 1/2] mm, debug: report when GFP_NO{FS,IO} is used explicitly from memalloc_no{fs,io}_{save,restore} context Michal Hocko
2017-01-06 14:18 ` [DEBUG PATCH 2/2] silent warnings which we cannot do anything about Michal Hocko
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