Hi Dave, I looked into killing the mrlock and ran into an unexpected problem. Currently mr_writer tracks that there is someone holding a write lock, lockdep on the other hand checks if the calling thread has that lock. While that generally is the right semantic, our hack to offload btree splits to a work item offends lockdep. E.g. this callstack now asserts: generic/256 [ 32.729465] run fstests generic/256 at 2016-09-05 15:09:48 [ 33.078511] XFS (vdc): Mounting V5 Filesystem [ 33.090875] XFS (vdc): Ending clean mount [ 59.158520] XFS: Assertion failed: xfs_isilocked(ip, XFS_ILOCK_EXCL), file: fs/xfs/xfs_trans_inode.c, line: 100 [ 59.159559] ------------[ cut here ]------------ [ 59.160034] kernel BUG at fs/xfs/xfs_message.c:113! [ 59.160367] invalid opcode: 0000 [#1] SMP [ 59.160633] Modules linked in: [ 59.160846] CPU: 3 PID: 7284 Comm: kworker/3:3 Not tainted 4.8.0-rc2+ #1149 [ 59.161056] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.7.5-20140531_083030-gandalf 04/01/2014 [ 59.161056] Workqueue: xfsalloc xfs_btree_split_worker [ 59.161056] task: ffff880136d25ac0 task.stack: ffff8800bb864000 [ 59.161056] RIP: 0010:[<ffffffff8159309d>] [<ffffffff8159309d>] assfail+0x1d/0x20 [ 59.161056] RSP: 0018:ffff8800bb867ba0 EFLAGS: 00010282 [ 59.161056] RAX: 00000000ffffffea RBX: ffff8801339f3300 RCX: 0000000000000021 [ 59.161056] RDX: ffff8800bb867ac8 RSI: 000000000000000a RDI: ffffffff82403b91 [ 59.161056] RBP: ffff8800bb867ba0 R08: 0000000000000000 R09: 0000000000000000 [ 59.161056] R10: 000000000000000a R11: f000000000000000 R12: 0000000000000001 [ 59.161056] R13: ffff8801356aaaf8 R14: ffff8800bb867bd8 R15: ffff8801352d1d98 [ 59.161056] FS: 0000000000000000(0000) GS:ffff88013fd80000(0000) knlGS:0000000000000000 [ 59.161056] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 59.161056] CR2: 000000000061ee00 CR3: 00000000bb956000 CR4: 00000000000006e0 [ 59.161056] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 59.161056] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 59.161056] Stack: [ 59.161056] ffff8800bb867bc8 ffffffff815b467d ffff8801352d1d98 ffff8800bba0fadc [ 59.161056] ffff8800bb867d10 ffff8800bb867c88 ffffffff81536c0d ffff8801356aaaf8 [ 59.161056] ffff88013ad64000 ffff8801370e3340 ffff8801373d5600 0000000000000000 [ 59.161056] Call Trace: [ 59.161056] [<ffffffff815b467d>] xfs_trans_log_inode+0x5d/0xd0 [ 59.161056] [<ffffffff81536c0d>] xfs_bmbt_alloc_block+0x15d/0x220 [ 59.161056] [<ffffffff8153d526>] __xfs_btree_split+0xb6/0xae0 [ 59.161056] [<ffffffff81e33907>] ? _raw_spin_unlock_irq+0x27/0x40 [ 59.161056] [<ffffffff8153dfc1>] xfs_btree_split_worker+0x71/0xb0 [ 59.161056] [<ffffffff810f58a1>] process_one_work+0x1c1/0x600 [ 59.161056] [<ffffffff810f581b>] ? process_one_work+0x13b/0x600 [ 59.161056] [<ffffffff810f5d44>] worker_thread+0x64/0x4a0 [ 59.161056] [<ffffffff810f5ce0>] ? process_one_work+0x600/0x600 [ 59.161056] [<ffffffff810fb951>] kthread+0xf1/0x110 [ 59.161056] [<ffffffff81e341ef>] ret_from_fork+0x1f/0x40 [ 59.161056] [<ffffffff810fb860>] ? kthread_create_on_node+0x200/0x200 While it previously did fine. I fear there might be other locking asserts in the code called from that work item as well. _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
