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From: Christoph Hellwig <hch@infradead.org>
To: xfs@oss.sgi.com
Subject: [PATCH] xfs: allow writeback from kswapd
Date: Mon, 28 Jun 2010 10:34:44 -0400	[thread overview]
Message-ID: <20100628143444.GB5473@infradead.org> (raw)

We only need disable I/O from direct or memcg reclaim.

Signed-off-by: Christoph Hellwig <hch@lst.de>

Index: xfs-dev/fs/xfs/linux-2.6/xfs_aops.c
===================================================================
--- xfs-dev.orig/fs/xfs/linux-2.6/xfs_aops.c	2010-06-28 11:57:06.652261386 +0200
+++ xfs-dev/fs/xfs/linux-2.6/xfs_aops.c	2010-06-28 11:59:17.846068204 +0200
@@ -1049,16 +1049,15 @@ xfs_vm_writepage(
 	/*
 	 * Refuse to write the page out if we are called from reclaim context.
 	 *
-	 * This is primarily to avoid stack overflows when called from deep
-	 * used stacks in random callers for direct reclaim, but disabling
-	 * reclaim for kswap is a nice side-effect as kswapd causes rather
-	 * suboptimal I/O patters, too.
+	 * This avoids stack overflows when called from deeply used stacks in
+	 * random callers for direct reclaim or memcg reclaim.  We explicitly
+	 * allow reclaim from kswapd as the stack usage there is relatively low.
 	 *
 	 * This should really be done by the core VM, but until that happens
 	 * filesystems like XFS, btrfs and ext4 have to take care of this
 	 * by themselves.
 	 */
-	if (current->flags & PF_MEMALLOC)
+	if ((current->flags & (PF_MEMALLOC|PF_KSWAPD)) == PF_MEMALLOC)
 		goto out_fail;
 
 	/*

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             reply	other threads:[~2010-06-28 14:31 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-06-28 14:34 Christoph Hellwig [this message]
2010-07-09 16:13 ` [PATCH] xfs: allow writeback from kswapd Christoph Hellwig
2010-07-12  3:37 ` Alex Elder

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