lkml.org 
[lkml]   [2011]   [May]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Date
    From
    Subject[PATCH 2/3] writeback: update dirtied_when for synced inode to prevent livelock
    With the more aggressive "keep writeback as long as we wrote something"
    logic in wb_writeback(), the "use LONG_MAX .nr_to_write" trick in commit
    b9543dac5bbc ("writeback: avoid livelocking WB_SYNC_ALL writeback") is
    no longer enough to stop sync livelock.

    The fix is to explicitly update .dirtied_when on synced inodes, so that
    they are no longer considered for writeback in the next round.

    CC: Jan Kara <jack@suse.cz>
    Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
    ---
    fs/fs-writeback.c | 9 +++++++++
    1 file changed, 9 insertions(+)

    ext3/ext4 are working fine now, however tests show that XFS may still
    livelock inside the XFS routines:

    [ 3581.181253] sync D ffff8800b6ca15d8 4560 4403 4392 0x00000000
    [ 3581.181734] ffff88006f775bc8 0000000000000046 ffff8800b6ca12b8 00000001b6ca1938
    [ 3581.182411] ffff88006f774000 00000000001d2e40 00000000001d2e40 ffff8800b6ca1280
    [ 3581.183088] 00000000001d2e40 ffff88006f775fd8 00000340af111ef2 00000000001d2e40
    [ 3581.183765] Call Trace:
    [ 3581.184008] [<ffffffff8109be73>] ? lock_release_holdtime+0xa3/0xab
    [ 3581.184392] [<ffffffff8108cc0d>] ? prepare_to_wait+0x6c/0x79
    [ 3581.184756] [<ffffffff8108cc0d>] ? prepare_to_wait+0x6c/0x79
    [ 3581.185120] [<ffffffff812ed520>] xfs_ioend_wait+0x87/0x9f
    [ 3581.185474] [<ffffffff8108c97a>] ? wake_up_bit+0x2a/0x2a
    [ 3581.185827] [<ffffffff812f742a>] xfs_sync_inode_data+0x92/0x9d
    [ 3581.186198] [<ffffffff812f76e2>] xfs_inode_ag_walk+0x1a5/0x287
    [ 3581.186569] [<ffffffff812f779b>] ? xfs_inode_ag_walk+0x25e/0x287
    [ 3581.186946] [<ffffffff812f7398>] ? xfs_sync_worker+0x69/0x69
    [ 3581.187311] [<ffffffff812e2354>] ? xfs_perag_get+0x68/0xd0
    [ 3581.187669] [<ffffffff81092175>] ? local_clock+0x41/0x5a
    [ 3581.188020] [<ffffffff8109be73>] ? lock_release_holdtime+0xa3/0xab
    [ 3581.188403] [<ffffffff812e22ec>] ? xfs_check_sizes+0x160/0x160
    [ 3581.188773] [<ffffffff812e2354>] ? xfs_perag_get+0x68/0xd0
    [ 3581.189130] [<ffffffff812e236c>] ? xfs_perag_get+0x80/0xd0
    [ 3581.189488] [<ffffffff812e22ec>] ? xfs_check_sizes+0x160/0x160
    [ 3581.189858] [<ffffffff812f7831>] ? xfs_inode_ag_iterator+0x6d/0x8f
    [ 3581.190241] [<ffffffff812f7398>] ? xfs_sync_worker+0x69/0x69
    [ 3581.190606] [<ffffffff812f780b>] xfs_inode_ag_iterator+0x47/0x8f
    [ 3581.190982] [<ffffffff811611f5>] ? __sync_filesystem+0x7a/0x7a
    [ 3581.191352] [<ffffffff812f7877>] xfs_sync_data+0x24/0x43
    [ 3581.191703] [<ffffffff812f7911>] xfs_quiesce_data+0x2c/0x88
    [ 3581.192065] [<ffffffff812f5556>] xfs_fs_sync_fs+0x21/0x48
    [ 3581.192419] [<ffffffff811611e1>] __sync_filesystem+0x66/0x7a
    [ 3581.192783] [<ffffffff8116120b>] sync_one_sb+0x16/0x18
    [ 3581.193128] [<ffffffff8113e3e3>] iterate_supers+0x72/0xce
    [ 3581.193482] [<ffffffff81161140>] sync_filesystems+0x20/0x22
    [ 3581.193842] [<ffffffff8116127e>] sys_sync+0x21/0x33
    [ 3581.194177] [<ffffffff819016c2>] system_call_fastpath+0x16/0x1b

    --- linux-next.orig/fs/fs-writeback.c 2011-05-02 11:16:50.000000000 +0800
    +++ linux-next/fs/fs-writeback.c 2011-05-02 11:17:24.000000000 +0800
    @@ -431,6 +431,15 @@ writeback_single_inode(struct inode *ino
    requeue_io(inode, wb);
    } else {
    /*
    + * sync livelock prevention: each inode is
    + * tagged and synced in one shot. If still
    + * dirty, move it back to s_dirty with updated
    + * dirty time to prevent syncing it again.
    + */
    + if (wbc->sync_mode == WB_SYNC_ALL ||
    + wbc->tagged_sync)
    + inode->dirtied_when = jiffies;
    + /*
    * Writeback blocked by something other than
    * congestion. Delay the inode for some time to
    * avoid spinning on the CPU (100% iowait)



    \
     
     \ /
      Last update: 2011-05-02 05:35    [W:0.025 / U:0.380 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site