On Wed, Sep 09 2015, Chris Mason wrote: > Commit d353d7587 added a plug/finish_plug pair to writeback_sb_inodes, > but writeback_sb_inodes has a horrible secret...it's called with the > wb->list_lock held. > > Btrfs raid5/6 and MD raid10 have horrible secrets of their own...they > both do allocations in their unplug callbacks. > > None of the options to fix it are very pretty. We don't want to kick > off workers for all of these unplugs, and the lock doesn't look hot > enough to justify bigger restructuring. > > [ 2854.025042] BUG: sleeping function called from invalid context at mm/page_alloc.c:3189 > [ 2854.041366] in_atomic(): 1, irqs_disabled(): 0, pid: 145562, name: kworker/u66:15 > [ 2854.056813] INFO: lockdep is turned off. > [ 2854.064870] CPU: 13 PID: 145562 Comm: kworker/u66:15 Not tainted 4.2.0-mason+ #1 > [ 2854.080082] Hardware name: ZTSYSTEMS Echo Ridge T4 /A9DRPF-10D, BIOS 1.07 05/10/2012 > [ 2854.096211] Workqueue: writeback wb_workfn (flush-btrfs-244) > [ 2854.107821] ffffffff81a2bbee ffff880ee09a7598 ffffffff813307bb ffff880ee09a7598 > [ 2854.123162] ffff881010d1ca00 ffff880ee09a75c8 ffffffff81086615 0000000000000000 > [ 2854.138556] 0000000000000000 0000000000000c75 ffffffff81a2bbee ffff880ee09a75f8 > [ 2854.153936] Call Trace: > [ 2854.181101] [<ffffffff81086722>] __might_sleep+0x52/0x90 > [ 2854.192136] [<ffffffff8116d2b4>] __alloc_pages_nodemask+0x344/0xbe0 > [ 2854.229682] [<ffffffff811b54aa>] alloc_pages_current+0x10a/0x1e0 > [ 2854.255508] [<ffffffffa0663f19>] full_stripe_write+0x59/0xc0 [btrfs] > [ 2854.268600] [<ffffffffa0663fb9>] __raid56_parity_write+0x39/0x60 [btrfs] > [ 2854.282385] [<ffffffffa06640fb>] run_plug+0x11b/0x140 [btrfs] > [ 2854.294259] [<ffffffffa0664143>] btrfs_raid_unplug+0x23/0x70 [btrfs] > [ 2854.307334] [<ffffffff81307622>] blk_flush_plug_list+0x82/0x1f0 > [ 2854.319542] [<ffffffff813077c4>] blk_finish_plug+0x34/0x50 > [ 2854.330878] [<ffffffff812079c2>] writeback_sb_inodes+0x122/0x580 > [ 2854.343256] [<ffffffff81208016>] wb_writeback+0x136/0x4e0 > > Signed-off-by: Chris Mason <clm@xxxxxx> Reviewed-by: Jens Axboe <axboe@xxxxxx> -- Jens Axboe -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
