• Tejun Heo's avatar
    writeback: set worker desc to identify writeback workers in task dumps · ef3b1019
    Tejun Heo authored
    Writeback has been recently converted to use workqueue instead of its
    private thread pool implementation.  One negative side effect of this
    conversion is that there's no easy to tell which backing device a
    writeback work item was working on at the time of task dump, be it
    sysrq-t, BUG, WARN or whatever, which, according to our writeback
    brethren, is important in tracking down issues with a lot of mounted
    file systems on a lot of different devices.
    
    This patch restores that information using the new worker description
    facility.  bdi_writeback_workfn() calls set_work_desc() to identify
    which bdi it's working on.  The description is printed out together with
    the worqueue name and worker function as in the following example dump.
    
     WARNING: at fs/fs-writeback.c:1015 bdi_writeback_workfn+0x2b4/0x3c0()
     Modules linked in:
     Pid: 28, comm: kworker/u18:0 Not tainted 3.9.0-rc1-work+ #24 empty empty/S3992
     Workqueue: writeback bdi_writeback_workfn (flush-8:16)
      ffffffff820a3a98 ffff88015b927cb8 ffffffff81c61855 ffff88015b927cf8
      ffffffff8108f500 0000000000000000 ffff88007a171948 ffff88007a1716b0
      ffff88015b49df00 ffff88015b8d3940 0000000000000000 ffff88015b927d08
     Call Trace:
      [<ffffffff81c61855>] dump_stack+0x19/0x1b
      [<ffffffff8108f500>] warn_slowpath_common+0x70/0xa0
      [<ffffffff8108f54a>] warn_slowpath_null+0x1a/0x20
      [<ffffffff81200144>] bdi_writeback_workfn+0x2b4/0x3c0
      [<ffffffff810b4c87>] process_one_work+0x1d7/0x660
      [<ffffffff810b5c72>] worker_thread+0x122/0x380
      [<ffffffff810bdfea>] kthread+0xea/0xf0
      [<ffffffff81c6cedc>] ret_from_fork+0x7c/0xb0
    Signed-off-by: default avatarTejun Heo <tj@kernel.org>
    Cc: Dave Chinner <david@fromorbit.com>
    Cc: Jan Kara <jack@suse.cz>
    Cc: Jens Axboe <axboe@kernel.dk>
    Cc: Oleg Nesterov <oleg@redhat.com>
    Cc: Ingo Molnar <mingo@redhat.com>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    ef3b1019
fs-writeback.c 39.6 KB