syzbot


INFO: task hung in ext4_fill_super
Status: upstream: reported C repro on 2021/06/16 09:56
Reported-by: syzbot+c9ff4822a62eee994ea3@syzkaller.appspotmail.com
First crash: 350d, last: 14d

Cause bisection: the issue happens on the oldest tested release (bisect log)
Crash: INFO: task hung in ext4_fill_super (log)
Repro: C syz .config
similar bugs (2):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-4.19 INFO: task hung in ext4_fill_super C error 9 166d 347d 0/1 upstream: reported C repro on 2021/06/15 09:47
linux-4.14 INFO: task hung in ext4_fill_super C 3 19d 292d 0/1 upstream: reported C repro on 2021/08/09 15:53
Patch testing requests:
Created Duration User Patch Repo Result
2021/08/06 07:45 18m paskripkin@gmail.com patch upstream OK
2021/08/05 14:26 18m paskripkin@gmail.com patch upstream OK
2021/06/16 16:22 13m paskripkin@gmail.com https://linux.googlesource.com/linux/kernel/git/torvalds/linux refs/changes/76/10176/6 report log

Sample crash report:
INFO: task syz-executor768:8567 blocked for more than 143 seconds.
      Not tainted 5.13.0-rc5-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor768 state:D stack:27544 pid: 8567 ppid:  8423 flags:0x00004004
Call Trace:
 context_switch kernel/sched/core.c:4339 [inline]
 __schedule+0x916/0x23e0 kernel/sched/core.c:5147
 schedule+0xcf/0x270 kernel/sched/core.c:5226
 schedule_timeout+0x1db/0x250 kernel/time/timer.c:1868
 do_wait_for_common kernel/sched/completion.c:85 [inline]
 __wait_for_common kernel/sched/completion.c:106 [inline]
 wait_for_common kernel/sched/completion.c:117 [inline]
 wait_for_completion+0x168/0x270 kernel/sched/completion.c:138
 kthread_stop+0x17a/0x720 kernel/kthread.c:642
 ext4_fill_super+0x87ac/0xdfa0 fs/ext4/super.c:5190
 mount_bdev+0x34d/0x410 fs/super.c:1368
 legacy_get_tree+0x105/0x220 fs/fs_context.c:592
 vfs_get_tree+0x89/0x2f0 fs/super.c:1498
 do_new_mount fs/namespace.c:2905 [inline]
 path_mount+0x132a/0x1fa0 fs/namespace.c:3235
 do_mount fs/namespace.c:3248 [inline]
 __do_sys_mount fs/namespace.c:3456 [inline]
 __se_sys_mount fs/namespace.c:3433 [inline]
 __x64_sys_mount+0x27f/0x300 fs/namespace.c:3433
 do_syscall_64+0x3a/0xb0 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x445b2a
RSP: 002b:00007ffc5efbf598 EFLAGS: 00000202 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ffc5efbf5f0 RCX: 0000000000445b2a
RDX: 0000000020000000 RSI: 00000000200000c0 RDI: 00007ffc5efbf5b0
RBP: 00007ffc5efbf5b0 R08: 00007ffc5efbf5f0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 00000000200003f8
R13: 0000000000000003 R14: 0000000000000004 R15: 0000000000000005

Showing all locks held in the system:
1 lock held by khungtaskd/1636:
 #0: ffffffff8bf79620 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:6333
2 locks held by in:imklog/8117:
 #0: ffff888015be9770 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe9/0x100 fs/file.c:974
 #1: ffff888021bc3958 (&mm->mmap_lock#2){++++}-{3:3}, at: file_ctx security/apparmor/include/file.h:33 [inline]
 #1: ffff888021bc3958 (&mm->mmap_lock#2){++++}-{3:3}, at: aa_file_perm+0x119/0x1170 security/apparmor/file.c:609
1 lock held by syz-executor768/8567:
 #0: ffff88802ac340e0 (&type->s_umount_key#27/1){+.+.}-{3:3}, at: alloc_super+0x1dd/0xab0 fs/super.c:229

=============================================

NMI backtrace for cpu 0
CPU: 0 PID: 1636 Comm: khungtaskd Not tainted 5.13.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:79 [inline]
 dump_stack+0x141/0x1d7 lib/dump_stack.c:120
 nmi_cpu_backtrace.cold+0x44/0xd7 lib/nmi_backtrace.c:105
 nmi_trigger_cpumask_backtrace+0x1b3/0x230 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:209 [inline]
 watchdog+0xd48/0xfb0 kernel/hung_task.c:294
 kthread+0x3b1/0x4a0 kernel/kthread.c:313
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1 skipped: idling at native_safe_halt arch/x86/include/asm/irqflags.h:51 [inline]
NMI backtrace for cpu 1 skipped: idling at arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline]
NMI backtrace for cpu 1 skipped: idling at acpi_safe_halt drivers/acpi/processor_idle.c:108 [inline]
NMI backtrace for cpu 1 skipped: idling at acpi_idle_do_entry+0x1c9/0x250 drivers/acpi/processor_idle.c:513

Fix bisection attempts:
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci-upstream-kasan-gce-root 2022/05/14 10:54 upstream ec7f49619d8e 1ba81399 .config log report syz C
ci-upstream-kasan-gce-root 2022/04/14 10:29 upstream a19944809fe9 1ba81399 .config log report syz C
ci-upstream-kasan-gce-root 2022/03/15 10:01 upstream 09688c0166e7 1ba81399 .config log report syz C
ci-upstream-kasan-gce-root 2022/02/13 04:43 upstream b81b1829e7e3 1ba81399 .config log report syz C
ci-upstream-kasan-gce-root 2022/01/13 20:19 upstream fb3b0673b7d5 1ba81399 .config log report syz C
ci-upstream-kasan-gce-root 2021/12/14 16:13 upstream 5472f14a3742 1ba81399 .config log report syz C
ci-upstream-kasan-gce-root 2021/11/14 14:50 upstream c8c109546a19 1ba81399 .config log report syz C
ci-upstream-kasan-gce-root 2021/10/15 03:53 upstream ec681c53f8d2 1ba81399 .config log report syz C
ci-upstream-kasan-gce-root 2021/09/15 03:27 upstream 3ca706c189db 1ba81399 .config log report syz C
ci-upstream-kasan-gce-root 2021/08/15 21:26 upstream ecf93431963a 1ba81399 .config log report syz C
ci-upstream-kasan-gce-root 2021/07/16 12:31 upstream d936eb238744 1ba81399 .config log report syz C
Crashes (4):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci-upstream-kasan-gce-root 2021/06/12 09:38 upstream f21b807c3cf8 1ba81399 .config log report syz C INFO: task hung in ext4_fill_super
ci-upstream-kasan-gce-root 2021/06/16 11:53 upstream 94f0b2d4a1d0 c06f97ad .config log report info INFO: task hung in ext4_fill_super
ci-upstream-kasan-gce-root 2021/06/14 10:18 upstream 009c9aa5be65 1ba81399 .config log report info INFO: task hung in ext4_fill_super
ci-upstream-kasan-gce-root 2021/06/12 06:43 upstream f21b807c3cf8 1ba81399 .config log report info INFO: task hung in ext4_fill_super