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From: Dave Chinner <david@fromorbit.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: xfs@oss.sgi.com
Subject: Re: [PATCH 02/17] xfs: skip writeback from reclaim context
Date: Wed, 2 Jun 2010 14:39:57 +1000	[thread overview]
Message-ID: <20100602043957.GB7011@dastard> (raw)
In-Reply-To: <20100531160859.184576507@bombadil.infradead.org>

On Mon, May 31, 2010 at 12:07:29PM -0400, Christoph Hellwig wrote:
> Allowing writeback from reclaim context causes massive problems with stack
> overflows as we can call into the writeback code which tends to be a heavy
> stack user both in the generic code and XFS from random contexts that
> perform memory allocations.
> 
> Follow the example of btrfs (and in slightly different form ext4) and refuse
> to write out data from reclaim context.  This issue should really be handled
> by the VM so that we can tune better for this case, but until we get it
> sorted out there we have to hack around this in each filesystem with a
> complex writeback path.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Yup, I agree that we have to do this for the moment. It hasn't
caused any problems in my usual OOM testing, so it seems safe
to do.

Reviewed-by: Dave Chinner <dchinner@redhat.com>

Also worth thinking about is if should be checked in
xfs_vm_releasepage() as well to avoid the same stack issues if it
triggers allocation...

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com

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  reply	other threads:[~2010-06-02  4:37 UTC|newest]

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-05-31 16:07 [PATCH 00/17] pending patches Christoph Hellwig
2010-05-31 16:07 ` [PATCH 01/17] xfs: remove done roadmap item from xfs-delayed-logging-design.txt Christoph Hellwig
2010-06-02  4:33   ` Dave Chinner
2010-05-31 16:07 ` [PATCH 02/17] xfs: skip writeback from reclaim context Christoph Hellwig
2010-06-02  4:39   ` Dave Chinner [this message]
2010-06-02 10:08     ` Christoph Hellwig
2010-06-02 23:02       ` Dave Chinner
2010-06-03  6:52         ` Christoph Hellwig
2010-06-03  6:52           ` Christoph Hellwig
2010-05-31 16:07 ` [PATCH 03/17] xfs: improve xfs_isilocked Christoph Hellwig
2010-06-02  4:41   ` Dave Chinner
2010-05-31 16:07 ` [PATCH 04/17] xfs: drop dmapi hooks Christoph Hellwig
2010-06-02  4:45   ` Dave Chinner
2010-05-31 16:07 ` [PATCH 05/17] xfs: remove unneeded #include statements Christoph Hellwig
2010-06-02  4:45   ` Dave Chinner
2010-05-31 16:07 ` [PATCH 06/17] xfs: simplify log item descriptor tracking Christoph Hellwig
2010-06-02  5:11   ` Dave Chinner
2010-05-31 16:07 ` [PATCH 07/17] xfs: merge iop_unpin_remove into iop_unpin Christoph Hellwig
2010-06-02  5:14   ` Dave Chinner
2010-05-31 16:07 ` [PATCH 08/17] xfs: give xfs_item_ops methods the correct prototypes Christoph Hellwig
2010-06-02  5:30   ` Dave Chinner
2010-05-31 16:07 ` [PATCH 09/17] xfs: give li_cb callbacks the correct prototype Christoph Hellwig
2010-06-02  5:45   ` Dave Chinner
2010-05-31 16:07 ` [PATCH 10/17] xfs: simplify buffer pinning Christoph Hellwig
2010-06-02  5:47   ` Dave Chinner
2010-05-31 16:07 ` [PATCH 11/17] xfs: simplify inode to transaction joining Christoph Hellwig
2010-06-02  5:57   ` Dave Chinner
2010-05-31 16:07 ` [PATCH 12/17] xfs: fix the xfs_log_iovec i_addr type Christoph Hellwig
2010-06-02  6:01   ` Dave Chinner
2010-05-31 16:07 ` [PATCH 13/17] xfs: kill the unused xlog_debug variable Christoph Hellwig
2010-06-02  6:02   ` Dave Chinner
2010-05-31 16:07 ` [PATCH 14/17] xfs: remove the unused XFS_LOG_SLEEP and XFS_LOG_NOSLEEP flags Christoph Hellwig
2010-06-02  6:02   ` Dave Chinner
2010-05-31 16:07 ` [PATCH 15/17] xfs: remove the unused XFS_TRANS_NOSLEEP/XFS_TRANS_WAIT flags Christoph Hellwig
2010-06-02  6:03   ` Dave Chinner
2010-05-31 16:07 ` [PATCH 16/17] xfs: remove unused XFS_BMAPI_ flags Christoph Hellwig
2010-06-02  6:04   ` Dave Chinner
2010-05-31 16:07 ` [PATCH 17/17] xfs: remove unused delta tracking code in xfs_bmapi Christoph Hellwig
2010-06-02  6:11   ` Dave Chinner
2010-06-02  6:13 ` [PATCH 00/17] pending patches Dave Chinner
2010-06-03 17:01 ` Alex Elder
2010-06-03 17:08   ` dropping dmapi support, was " Christoph Hellwig
2010-06-03 22:33     ` Dave Chinner

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