https://bugzilla.kernel.org/show_bug.cgi?id=102751 Bug ID: 102751 Summary: infinite loop in jbd2_journal_destroy() Product: File System Version: 2.5 Kernel Version: 4.1.5 Hardware: All OS: Linux Tree: Mainline Status: NEW Severity: normal Priority: P1 Component: ext4 Assignee: fs_ext4@xxxxxxxxxxxxxxxxxxxx Reporter: mihai.dontu@xxxxxxxxx Regression: No While watching a video from a removable disk (USB), the connecting cable failed (too much use) and I had to unplug it. I noticed, however, that vlc has started consuming 100% CPU time while being zombie. An Alt+SysReq+l showed this: NMI backtrace for cpu 2 CPU: 2 PID: 17378 Comm: vlc Tainted: G O 4.1.5-gentoo #1 Hardware name: Dell Inc. Latitude E7440/07F3F4, BIOS A15 05/19/2015 task: ffff88029d050000 ti: ffff8802cd80c000 task.ti: ffff8802cd80c000 RIP: 0010:[<ffffffff8cec3320>] [<ffffffff8cec3320>] mutex_unlock+0x10/0x20 RSP: 0018:ffff8802cd80fcd0 EFLAGS: 00000202 RAX: 00000000fffffffb RBX: ffff880084068000 RCX: 0000000000000000 RDX: 0000000080000001 RSI: 0000000000000000 RDI: ffff8800840680e8 RBP: ffff8802cd80fd38 R08: 000000000000000a R09: 00000000000004b0 R10: 0000000000017e98 R11: 00000000000004b0 R12: ffff880084068398 R13: ffff8800840680e8 R14: ffff8802cd80fcf0 R15: ffff8800840680a0 FS: 00007fa8ac663700(0000) GS:ffff88041eb00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f5b3e946000 CR3: 000000000d80d000 CR4: 00000000001426e0 Stack: ffffffff8c3d1318 ffff880200000000 ffff88029d050000 ffffffff8c179cc0 ffff8802cd80fcf0 ffff8802cd80fcf0 0000000028b119c8 ffff88015d99c400 ffff88008406c000 ffff880185940400 ffff880084068800 ffff88029d050000 Call Trace: [<ffffffff8c3d1318>] ? jbd2_journal_destroy+0x138/0x240 [<ffffffff8c179cc0>] ? wake_atomic_t_function+0x60/0x60 [<ffffffff8c38f0e7>] ext4_put_super+0x67/0x360 [<ffffffff8c29d726>] generic_shutdown_super+0x76/0x100 [<ffffffff8c29dae7>] kill_block_super+0x27/0x80 [<ffffffff8c29de59>] deactivate_locked_super+0x49/0x80 [<ffffffff8c29e2cc>] deactivate_super+0x6c/0x80 [<ffffffff8c2bc033>] cleanup_mnt+0x43/0xa0 [<ffffffff8c2bc0e2>] __cleanup_mnt+0x12/0x20 [<ffffffff8c153804>] task_work_run+0xd4/0xf0 [<ffffffff8c139174>] do_exit+0x2f4/0xb90 [<ffffffff8c1d381c>] ? __audit_syscall_entry+0xac/0x100 [<ffffffff8c05f745>] ? do_audit_syscall_entry+0x55/0x80 [<ffffffff8c139a9b>] do_group_exit+0x3b/0xb0 [<ffffffff8c139b24>] SyS_exit_group+0x14/0x20 [<ffffffff8cec59db>] system_call_fastpath+0x16/0x6e Code: ff 4c 89 e7 e8 d2 1e 00 00 5b 41 5c 5d c3 0f 1f 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 c7 47 18 00 00 00 00 f0 ff 07 <7f> 0a 55 48 89 e5 e8 95 ff ff ff 5d c3 0f 1f 00 0f 1f 44 00 00 and perf top (first 9 lines): 18.08% [kernel] [k] _raw_spin_lock 17.97% [kernel] [k] mutex_lock 15.36% [kernel] [k] mutex_unlock 10.89% [kernel] [k] _raw_spin_unlock 6.49% [kernel] [k] jbd2_log_do_checkpoint 6.16% [kernel] [k] preempt_count_add 4.53% [kernel] [k] jbd2_cleanup_journal_tail 3.96% [kernel] [k] preempt_count_sub 3.21% [kernel] [k] jbd2_journal_destroy Looking at the code it would seem that I've hit a race in: while (journal->j_checkpoint_transactions != NULL) { ... } because it's waiting for a transaction that cannot take place: Buffer I/O error on dev dm-1, logical block 243826688, lost sync page write JBD2: Error -5 detected when updating journal superblock for dm-1-8. Aborting journal on device dm-1-8. Buffer I/O error on dev dm-1, logical block 243826688, lost sync page write JBD2: Error -5 detected when updating journal superblock for dm-1-8. Maybe the loop should be abandoned on jbd2_log_do_checkpoint() error? The USB failure happened several times before, but I've never seen vlc get stuck. This also means that I'm unlikely to be able to reproduce this. :-( One more detail: the ext4 filesystem sits on top a LUKS device. -- You are receiving this mail because: You are watching the assignee of the bug. -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
