linux-kernel - Re: [PATCH 0/15] Per-bdi writeback flusher threads v10

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Date:	Tue, 16 Jun 2009 09:06:37 +0800
From:	"Zhang, Yanmin" <yanmin_zhang@...ux.intel.com>
To:	Jens Axboe <jens.axboe@...cle.com>
Cc:	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	chris.mason@...cle.com, david@...morbit.com, hch@...radead.org,
	akpm@...ux-foundation.org, jack@...e.cz, richard@....demon.co.uk,
	damien.wyart@...e.fr, dedekind1@...il.com, fweisbec@...il.com
Subject: Re: [PATCH 0/15] Per-bdi writeback flusher threads v10

On Fri, 2009-06-12 at 14:54 +0200, Jens Axboe wrote:
> Hi,
> 
> Here's the 10th version of the writeback patches. Changes since v9:
> 
> - Fix bdi task exit race leaving work on the list, flush it after we
>   know we cannot be found anymore.
> - Rename flusher tasks from bdi-foo to flush-foo. Should make it more
>   clear to the casual observer.
> - Fix a problem with the btrfs bdi register patch that would spew
>   warnings for > 1 mounted btrfs file system.
> - Rebase to current -git, there were some conflicts with the latest work
>   from viro/hch.
> - Fix a block layer core problem were stacked devices would overwrite
>   the bdi state, causing problems and warning spew.
> - In bdi_writeback_all(), in the race occurence of a work allocation
>   failure, restart scanning from the beginning. Then we can drop the
>   bdi_lock mutex before diving into bdi specific writeback.
> - Convert bdi_lock to a spinlock.
> - Use spin_trylock() in bdi_writeback_all(), if this isn't a data
>   integrity writeback. Debatable, I kind of like it...
> - Get rid of BDI_CAP_FLUSH_FORKER, just check for match with the
>   default_backing_dev_info.
> - Fix race in list checking in bdi_forker_task().
> 
> 
> For ease of patching, I've put the full diff here:
> 
>   http://kernel.dk/writeback-v10.patch
Jens,

I applied the patch to 2.6.30 and got a confliction. The attachment is
the patch I ported to 2.6.30. Did I miss anything?


With the patch, kernel reports below messages on 2 machines.

INFO: task sync:29984 blocked for more than 120 seconds.
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
sync          D ffff88002805e300  6168 29984  24581
 ffff88022f84b780 0000000000000082 7fffffffffffffff ffff880133dbfe70
 0000000000000000 ffff88022e2b4c50 ffff88022e2b4fd8 00000001000c7bb8
 ffff88022f513fd0 ffff880133dbfde8 ffff880133dbfec8 ffff88022d5d13c8
Call Trace:
 [<ffffffff802b69e4>] ? bdi_sched_wait+0x0/0xd
 [<ffffffff80780fde>] ? schedule+0x9/0x1d
 [<ffffffff802b69ed>] ? bdi_sched_wait+0x9/0xd
 [<ffffffff8078158d>] ? __wait_on_bit+0x40/0x6f
 [<ffffffff802b69e4>] ? bdi_sched_wait+0x0/0xd
 [<ffffffff80781628>] ? out_of_line_wait_on_bit+0x6c/0x78
 [<ffffffff8024a426>] ? wake_bit_function+0x0/0x23
 [<ffffffff802b67ac>] ? bdi_writeback_all+0x12a/0x152
 [<ffffffff802b6805>] ? generic_sync_sb_inodes+0x31/0xde
 [<ffffffff802b6935>] ? sync_inodes_sb+0x83/0x88
 [<ffffffff802b6980>] ? __sync_inodes+0x46/0x8f
 [<ffffffff802b94f2>] ? do_sync+0x36/0x5a
 [<ffffffff802b9538>] ? sys_sync+0xe/0x12
 [<ffffffff8020b9ab>] ? system_call_fastpath+0x16/0x1b

> 
> and also stored this in a writeback-v10 branch that will not change,
> you can pull that into Linus tree from here:
> 
>   git://git.kernel.dk/linux-2.6-block.git writeback-v10
> 
> Please test and report results/interesting finds. Thanks!
> 
>  b/block/blk-core.c            |    6 
>  b/block/blk-settings.c        |    4 
>  b/drivers/block/aoe/aoeblk.c  |    1 
>  b/drivers/char/mem.c          |    1 
>  b/fs/btrfs/disk-io.c          |   27 -
>  b/fs/buffer.c                 |    2 
>  b/fs/char_dev.c               |    1 
>  b/fs/configfs/inode.c         |    1 
>  b/fs/fs-writeback.c           |  818 +++++++++++++++++++++++++++-------
>  b/fs/fuse/inode.c             |    1 
>  b/fs/hugetlbfs/inode.c        |    1 
>  b/fs/nfs/client.c             |    1 
>  b/fs/ocfs2/dlm/dlmfs.c        |    1 
>  b/fs/ramfs/inode.c            |    1 
>  b/fs/super.c                  |    3 
>  b/fs/sysfs/inode.c            |    1 
>  b/fs/ubifs/super.c            |    4 
>  b/include/linux/backing-dev.h |   72 ++
>  b/include/linux/fs.h          |   11 
>  b/include/linux/writeback.h   |   15 
>  b/kernel/cgroup.c             |    1 
>  b/mm/Makefile                 |    2 
>  b/mm/backing-dev.c            |  519 +++++++++++++++++++++
>  b/mm/page-writeback.c         |  157 ------
>  b/mm/swap_state.c             |    1 
>  b/mm/vmscan.c                 |    2 
>  mm/pdflush.c                  |  269 -----------
>  27 files changed, 1317 insertions(+), 606 deletions(-)
> 

View attachment "writeback-v10_port.patch" of type "text/x-patch" (82832 bytes)