iouring locking issue in io_req_complete_post() / io_rsrc_node_ref_zero()
From: Nadav Amit <hidden>
Date: 2021-08-09 04:36:23
Jens, others, Sorry for bothering again, but I encountered a lockdep assertion failure: [ 106.009878] ------------[ cut here ]------------ [ 106.012487] WARNING: CPU: 2 PID: 1777 at kernel/softirq.c:364 __local_bh_enable_ip+0xaa/0xe0 [ 106.014524] Modules linked in: [ 106.015174] CPU: 2 PID: 1777 Comm: umem Not tainted 5.13.1+ #161 [ 106.016653] Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 07/22/2020 [ 106.018959] RIP: 0010:__local_bh_enable_ip+0xaa/0xe0 [ 106.020344] Code: a9 00 ff ff 00 74 38 65 ff 0d a2 21 8c 7a e8 ed 1a 20 00 fb 66 0f 1f 44 00 00 5b 41 5c 5d c3 65 8b 05 e6 2d 8c 7a 85 c0 75 9a <0f> 0b eb 96 e8 2d 1f 20 00 eb a5 4c 89 e7 e8 73 4f 0c 00 eb ae 65 [ 106.026258] RSP: 0018:ffff88812e58fcc8 EFLAGS: 00010046 [ 106.028143] RAX: 0000000000000000 RBX: 0000000000000201 RCX: dffffc0000000000 [ 106.029626] RDX: 0000000000000007 RSI: 0000000000000201 RDI: ffffffff8898c5ac [ 106.031340] RBP: ffff88812e58fcd8 R08: ffffffff8575dbbf R09: ffffed1028ef14f9 [ 106.032938] R10: ffff88814778a7c3 R11: ffffed1028ef14f8 R12: ffffffff85c9e9ae [ 106.034363] R13: ffff88814778a000 R14: ffff88814778a7b0 R15: ffff8881086db890 [ 106.036115] FS: 00007fbcfee17700(0000) GS:ffff8881e0300000(0000) knlGS:0000000000000000 [ 106.037855] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 106.039010] CR2: 000000c0402a5008 CR3: 000000011c1ac003 CR4: 00000000003706e0 [ 106.040453] Call Trace: [ 106.041245] _raw_spin_unlock_bh+0x31/0x40 [ 106.042543] io_rsrc_node_ref_zero+0x13e/0x190 [ 106.043471] io_dismantle_req+0x215/0x220 [ 106.044297] io_req_complete_post+0x1b8/0x720 [ 106.045456] __io_complete_rw.isra.0+0x16b/0x1f0 [ 106.046593] io_complete_rw+0x10/0x20 [ .... The rest of the call-stack is my stuff ] Apparently, io_req_complete_post() disables IRQs and this code-path seems valid (IOW: I did not somehow cause this failure). I am not familiar with this code, so some feedback would be appreciated. Thanks, Nadav