bisecting fixing commit since f21b807c3cf8cd7c5ca9e406b27bf1cd2f1c1238
building syzkaller on 1ba81399e2d03b53a7e631c4ab05f25af1fb1911
testing commit f21b807c3cf8cd7c5ca9e406b27bf1cd2f1c1238
compiler: gcc (GCC) 10.2.1 20210217, GNU ld (GNU Binutils for Debian) 2.35.2
kernel signature: 8b21325b923fb20a897d5cf3ff1b49eb35e00ef1ffefe76ca64cf7567fdeef74
all runs: crashed: INFO: task hung in ext4_fill_super
testing current HEAD c8c109546a19613d323a319d0c921cb1f317e629
testing commit c8c109546a19613d323a319d0c921cb1f317e629
compiler: gcc (GCC) 10.2.1 20210217, GNU ld (GNU Binutils for Debian) 2.35.2
kernel signature: 78f4371b63c07a38a3b348679cc268ed372770fb4f571a411bb5bd62a37a3983
all runs: crashed: INFO: task hung in ext4_stop_mmpd
revisions tested: 2, total time: 24m49.687612432s (build: 12m23.942673019s, test: 11m49.434940235s)
the crash still happens on HEAD
commit msg: Merge tag 'zstd-for-linus-v5.16' of git://github.com/terrelln/linux
crash: INFO: task hung in ext4_stop_mmpd
INFO: task syz-executor.0:9315 blocked for more than 143 seconds.
Not tainted 5.15.0-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor.0 state:D stack:27880 pid: 9315 ppid: 7069 flags:0x00004004
Call Trace:
context_switch kernel/sched/core.c:4969 [inline]
__schedule+0x90d/0x26c0 kernel/sched/core.c:6250
schedule+0xd2/0x260 kernel/sched/core.c:6323
schedule_timeout+0x19d/0x250 kernel/time/timer.c:1857
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+0x174/0x270 kernel/sched/completion.c:138
kthread_stop+0x104/0x4f0 kernel/kthread.c:648
ext4_stop_mmpd+0x34/0xb0 fs/ext4/mmp.c:255
ext4_fill_super+0x7b61/0xb6a0 fs/ext4/super.c:5068
mount_bdev+0x2cb/0x3b0 fs/super.c:1370
legacy_get_tree+0xfa/0x1f0 fs/fs_context.c:610
vfs_get_tree+0x7f/0x2c0 fs/super.c:1500
do_new_mount fs/namespace.c:2988 [inline]
path_mount+0x7e8/0x1a40 fs/namespace.c:3318
do_mount fs/namespace.c:3331 [inline]
__do_sys_mount fs/namespace.c:3539 [inline]
__se_sys_mount fs/namespace.c:3516 [inline]
__x64_sys_mount+0x1f5/0x260 fs/namespace.c:3516
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x467afa
RSP: 002b:00007fe01ba5afa8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 0000000020000380 RCX: 0000000000467afa
RDX: 0000000020000000 RSI: 00000000200000c0 RDI: 00007fe01ba5b000
RBP: 00007fe01ba5b040 R08: 00007fe01ba5b040 R09: 0000000020000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000020000000
R13: 00000000200000c0 R14: 00007fe01ba5b000 R15: 0000000020000200
INFO: task syz-executor.1:9331 blocked for more than 143 seconds.
Not tainted 5.15.0-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor.1 state:D stack:27904 pid: 9331 ppid: 7070 flags:0x00004004
Call Trace:
context_switch kernel/sched/core.c:4969 [inline]
__schedule+0x90d/0x26c0 kernel/sched/core.c:6250
schedule+0xd2/0x260 kernel/sched/core.c:6323
schedule_timeout+0x19d/0x250 kernel/time/timer.c:1857
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+0x174/0x270 kernel/sched/completion.c:138
kthread_stop+0x104/0x4f0 kernel/kthread.c:648
ext4_stop_mmpd+0x34/0xb0 fs/ext4/mmp.c:255
ext4_fill_super+0x7b61/0xb6a0 fs/ext4/super.c:5068
mount_bdev+0x2cb/0x3b0 fs/super.c:1370
legacy_get_tree+0xfa/0x1f0 fs/fs_context.c:610
vfs_get_tree+0x7f/0x2c0 fs/super.c:1500
do_new_mount fs/namespace.c:2988 [inline]
path_mount+0x7e8/0x1a40 fs/namespace.c:3318
do_mount fs/namespace.c:3331 [inline]
__do_sys_mount fs/namespace.c:3539 [inline]
__se_sys_mount fs/namespace.c:3516 [inline]
__x64_sys_mount+0x1f5/0x260 fs/namespace.c:3516
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x467afa
RSP: 002b:00007ffa0b2fefa8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 0000000020000380 RCX: 0000000000467afa
RDX: 0000000020000000 RSI: 00000000200000c0 RDI: 00007ffa0b2ff000
RBP: 00007ffa0b2ff040 R08: 00007ffa0b2ff040 R09: 0000000020000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000020000000
R13: 00000000200000c0 R14: 00007ffa0b2ff000 R15: 0000000020000200
Showing all locks held in the system:
2 locks held by kworker/u4:0/8:
1 lock held by khungtaskd/27:
#0: ffffffff8ad78840 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:6458
1 lock held by in:imklog/6256:
#0: ffff888077144ff0 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x9c/0xb0 fs/file.c:990
1 lock held by syz-executor.0/9315:
#0: ffff88801bc9e0e0 (&type->s_umount_key#27/1){+.+.}-{3:3}, at: alloc_super+0x192/0xa10 fs/super.c:229
1 lock held by syz-executor.1/9331:
#0: ffff888020e460e0 (&type->s_umount_key#27/1){+.+.}-{3:3}, at: alloc_super+0x192/0xa10 fs/super.c:229
1 lock held by syz-executor.3/9365:
#0: ffff88807562e0e0 (&type->s_umount_key#27/1){+.+.}-{3:3}, at: alloc_super+0x192/0xa10 fs/super.c:229
=============================================
NMI backtrace for cpu 1
CPU: 1 PID: 27 Comm: khungtaskd Not tainted 5.15.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x57/0x7d lib/dump_stack.c:106
nmi_cpu_backtrace.cold+0x30/0xc0 lib/nmi_backtrace.c:105
nmi_trigger_cpumask_backtrace+0x11a/0x160 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:210 [inline]
watchdog+0x88c/0xbf0 kernel/hung_task.c:295
kthread+0x3ab/0x480 kernel/kthread.c:327
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 8 Comm: kworker/u4:0 Not tainted 5.15.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events_unbound toggle_allocation_gate
RIP: 0010:lookup_chain_cache kernel/locking/lockdep.c:3694 [inline]
RIP: 0010:lookup_chain_cache_add kernel/locking/lockdep.c:3714 [inline]
RIP: 0010:validate_chain kernel/locking/lockdep.c:3769 [inline]
RIP: 0010:__lock_acquire+0x15ef/0x5410 kernel/locking/lockdep.c:5027
Code: 49 0f af ef 48 c1 ed 30 48 8d 04 ed a0 38 fe 8e 48 89 c2 48 89 44 24 08 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 80 3c 02 00 <0f> 85 dd 2c 00 00 48 8b 1c ed a0 38 fe 8e 48 85 db 74 58 48 83 eb
RSP: 0018:ffffc90000cd7738 EFLAGS: 00000046
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffffff8153733d
RDX: 1ffffffff1e046a2 RSI: 0000000000000008 RDI: ffffffff8f073940
RBP: 0000000000007f8e R08: 0000000000000000 R09: ffffffff8f073947
R10: fffffbfff1e0e728 R11: 0000000000000000 R12: ffff88801094e0d8
R13: ffff88801094d640 R14: 0000000000000000 R15: 3469074b3b3f0742
FS: 0000000000000000(0000) GS:ffff8880b9e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ff1bf65a000 CR3: 000000000aa8e000 CR4: 0000000000350ef0
Call Trace:
lock_acquire kernel/locking/lockdep.c:5637 [inline]
lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5602
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0x39/0x50 kernel/locking/spinlock.c:162
debug_object_activate+0x12e/0x3e0 lib/debugobjects.c:661
debug_timer_activate kernel/time/timer.c:729 [inline]
__mod_timer+0x55d/0xba0 kernel/time/timer.c:1050
schedule_timeout+0x118/0x250 kernel/time/timer.c:1880
toggle_allocation_gate mm/kfence/core.c:739 [inline]
toggle_allocation_gate+0x275/0x310 mm/kfence/core.c:724
process_one_work+0x87f/0x1450 kernel/workqueue.c:2298
worker_thread+0x598/0x1040 kernel/workqueue.c:2445
kthread+0x3ab/0x480 kernel/kthread.c:327
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
----------------
Code disassembly (best guess):
0: 49 0f af ef imul %r15,%rbp
4: 48 c1 ed 30 shr $0x30,%rbp
8: 48 8d 04 ed a0 38 fe lea -0x7101c760(,%rbp,8),%rax
f: 8e
10: 48 89 c2 mov %rax,%rdx
13: 48 89 44 24 08 mov %rax,0x8(%rsp)
18: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax
1f: fc ff df
22: 48 c1 ea 03 shr $0x3,%rdx
26: 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1)
* 2a: 0f 85 dd 2c 00 00 jne 0x2d0d <-- trapping instruction
30: 48 8b 1c ed a0 38 fe mov -0x7101c760(,%rbp,8),%rbx
37: 8e
38: 48 85 db test %rbx,%rbx
3b: 74 58 je 0x95
3d: 48 rex.W
3e: 83 .byte 0x83
3f: eb .byte 0xeb