Hi, It has been a long time, once I enable lockdep in kernel config, and a reboot I always receive the following lockdep warning, [ 7.615492] WARNING: CPU: 1 PID: 859 at kernel/locking/lockdep.c:746 register_lock_class+0x509/0x5b0 [ 7.620268] Modules linked in: [snipped] [ 7.620327] CPU: 1 PID: 859 Comm: bcache-register Not tainted 5.1.0-rc1-lp151.20-default+ #4 [ 7.620328] Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 04/13/2018 [ 7.620331] RIP: 0010:register_lock_class+0x509/0x5b0 [ 7.620332] Code: 2a 7c 00 e9 ff fb ff ff 48 8d 74 24 30 4c 89 f7 e8 bc f8 14 00 84 c0 74 25 48 8b 44 24 30 48 89 04 24 49 89 06 e9 5b fc ff ff <0f> 0b e9 ac fb ff ff 45 8b a4 24 30 01 00 00 e9 ce fd ff ff 48 8d [ 7.620333] RSP: 0018:ffffc90002a0fa18 EFLAGS: 00010083 [ 7.620333] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000911 [ 7.620334] RDX: ffffffff82b36d00 RSI: ffffffffa055ddfa RDI: 0000000000000000 [ 7.620334] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 [ 7.620334] R10: 0000000000000001 R11: 0000000000000000 R12: ffff88840e188300 [ 7.620334] R13: 0000000000000000 R14: ffff888417bbd0d0 R15: ffffffff82b4bd40 [ 7.620335] FS: 00007f74add0fbc0(0000) GS:ffff88841fe00000(0000) knlGS:0000000000000000 [ 7.620336] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 7.620336] CR2: 00007fa6c9699860 CR3: 000000041b1fc005 CR4: 00000000003606e0 [ 7.620378] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 7.703162] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 7.703163] Call Trace: [ 7.703169] ? __kernel_text_address+0xe/0x30 [ 7.703170] ? unwind_get_return_address+0x1b/0x30 [ 7.703172] ? __save_stack_trace+0x92/0x100 [ 7.703173] __lock_acquire.isra.36+0x4c/0x990 [ 7.703175] lock_acquire+0xb5/0x150 [ 7.703182] ? mca_reap+0x5f/0x1a0 [bcache] [ 7.703183] down_write_trylock+0x58/0x70 [ 7.703186] ? mca_reap+0x5f/0x1a0 [bcache] [ 7.703189] mca_reap+0x5f/0x1a0 [bcache] [ 7.703193] mca_alloc+0xbc/0x500 [bcache] [ 7.703194] ? up_read+0x90/0x90 [ 7.703197] bch_btree_node_get+0x109/0x2b0 [bcache] [ 7.703202] run_cache_set+0x310/0x9a0 [bcache] [ 7.703207] ? register_bcache+0xe5d/0x1280 [bcache] [ 7.703210] register_bcache+0xe5d/0x1280 [bcache] [ 7.703211] ? __lock_acquire.isra.36+0x36b/0x990 [ 7.703214] ? kernfs_fop_write+0x109/0x190 [ 7.703214] kernfs_fop_write+0x109/0x190 [ 7.703216] vfs_write+0xc1/0x1c0 [ 7.703217] ksys_write+0x55/0xc0 [ 7.703219] do_syscall_64+0x65/0x180 [ 7.703221] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 7.703222] RIP: 0033:0x7f74ad1acbd4 [ 7.703224] Code: 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b7 0f 1f 80 00 00 00 00 8b 05 5a fc 2c 00 48 63 ff 85 c0 75 13 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 54 f3 c3 66 90 55 53 48 89 d5 48 89 f3 48 83 [ 7.703224] RSP: 002b:00007ffc45e5e178 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 [ 7.703225] RAX: ffffffffffffffda RBX: 0000000000000009 RCX: 00007f74ad1acbd4 [ 7.703225] RDX: 0000000000000009 RSI: 000055d86834a260 RDI: 0000000000000003 [ 7.703226] RBP: 000055d86834a260 R08: 0000000000000008 R09: 00000000ffffffff [ 7.703226] R10: 00007ffc45e5ebcb R11: 0000000000000246 R12: 0000000000000009 [ 7.703226] R13: 0000000000000001 R14: 00007ffc45e5e220 R15: 0000000000000009 [ 7.703228] ---[ end trace 6de5302b578fb68b ]--- I am not familiar with lockdep engine, and not sure whether such warning hurts anything (so far it looks fine). Can anybody give me a hint, where and how to start diagnosing the problem and solve the warning ? Thanks in advance. -- Coly Li
