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Message-Id: <20101213064839.047784036@intel.com>
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Date: Mon, 13 Dec 2010 14:43:06 +0800
From: Wu Fengguang <fengguang.wu@intel.com>
To: Andrew Morton <akpm@linux-foundation.org>
CC: Jan Kara <jack@suse.cz>, Wu Fengguang <fengguang.wu@intel.com>
CC: Christoph Hellwig <hch@lst.de>
CC: Trond Myklebust <Trond.Myklebust@netapp.com>
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CC: "Theodore Ts'o" <tytso@mit.edu>
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Cc: linux-mm <linux-mm@kvack.org>
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Subject: [PATCH 17/47] writeback: do uninterruptible sleep in balance_dirty_pages()
References: <20101213064249.648862451@intel.com>
Content-Disposition: inline; filename=writeback-pause-TASK_UNINTERRUPTIBLE.patch
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Comments from Andrew Morton:

Using TASK_INTERRUPTIBLE in balance_dirty_pages() seems wrong.  If it's
going to do that then it must break out if signal_pending(), otherwise
it's pretty much guaranteed to degenerate into a busywait loop.  Plus
we *do* want these processes to appear in D state and to contribute to
load average.

So it should be TASK_UNINTERRUPTIBLE.

Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
---
 mm/page-writeback.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- linux-next.orig/mm/page-writeback.c	2010-12-08 22:44:26.000000000 +0800
+++ linux-next/mm/page-writeback.c	2010-12-08 22:44:27.000000000 +0800
@@ -673,7 +673,7 @@ pause:
 					  pages_dirtied,
 					  pause);
 		bdi_update_write_bandwidth(bdi, &bw_time, &bw_written);
-		__set_current_state(TASK_INTERRUPTIBLE);
+		__set_current_state(TASK_UNINTERRUPTIBLE);
 		io_schedule_timeout(pause);
 		bdi_update_write_bandwidth(bdi, &bw_time, &bw_written);