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 a19944809fe9942e6a96292490717904d0690c21
testing commit a19944809fe9942e6a96292490717904d0690c21
compiler: gcc (GCC) 10.2.1 20210217, GNU ld (GNU Binutils for Debian) 2.35.2
kernel signature: 056044d6b1381a2b208d84ac2ba1e5f1bb63c5b6e0826661f50f03116dea92a2
all runs: crashed: INFO: task hung in ext4_stop_mmpd
revisions tested: 2, total time: 27m58.887860001s (build: 16m22.831690825s, test: 10m55.094223124s)
the crash still happens on HEAD
commit msg: Merge tag 'hardening-v5.18-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux
crash: INFO: task hung in ext4_stop_mmpd
INFO: task syz-executor.2:4021 blocked for more than 143 seconds.
Not tainted 5.18.0-rc2-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor.2 state:D stack:27584 pid: 4021 ppid: 3918 flags:0x00004004
Call Trace:
context_switch kernel/sched/core.c:5073 [inline]
__schedule+0x913/0x26a0 kernel/sched/core.c:6388
schedule+0xd2/0x1f0 kernel/sched/core.c:6460
schedule_timeout+0x19d/0x250 kernel/time/timer.c:1857
do_wait_for_common kernel/sched/completion.c:85 [inline]
__wait_for_common+0x373/0x530 kernel/sched/completion.c:106
kthread_stop+0x104/0x4f0 kernel/kthread.c:708
ext4_stop_mmpd+0x34/0xb0 fs/ext4/mmp.c:255
__ext4_fill_super fs/ext4/super.c:5538 [inline]
ext4_fill_super+0x8766/0xc070 fs/ext4/super.c:5587
get_tree_bdev+0x398/0x680 fs/super.c:1292
vfs_get_tree+0x7f/0x2c0 fs/super.c:1497
do_new_mount fs/namespace.c:3040 [inline]
path_mount+0x7e8/0x1a40 fs/namespace.c:3370
do_mount fs/namespace.c:3383 [inline]
__do_sys_mount fs/namespace.c:3591 [inline]
__se_sys_mount fs/namespace.c:3568 [inline]
__x64_sys_mount+0x1f5/0x260 fs/namespace.c:3568
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0x80 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x467afa
RSP: 002b:00007fa4d5ca9fa8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 0000000020000380 RCX: 0000000000467afa
RDX: 0000000020000000 RSI: 00000000200000c0 RDI: 00007fa4d5caa000
RBP: 00007fa4d5caa040 R08: 00007fa4d5caa040 R09: 0000000020000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000020000000
R13: 00000000200000c0 R14: 00007fa4d5caa000 R15: 0000000020000200
INFO: task syz-executor.3:4040 blocked for more than 143 seconds.
Not tainted 5.18.0-rc2-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor.3 state:D stack:27576 pid: 4040 ppid: 3924 flags:0x00004004
Call Trace:
context_switch kernel/sched/core.c:5073 [inline]
__schedule+0x913/0x26a0 kernel/sched/core.c:6388
schedule+0xd2/0x1f0 kernel/sched/core.c:6460
schedule_timeout+0x19d/0x250 kernel/time/timer.c:1857
do_wait_for_common kernel/sched/completion.c:85 [inline]
__wait_for_common+0x373/0x530 kernel/sched/completion.c:106
kthread_stop+0x104/0x4f0 kernel/kthread.c:708
ext4_stop_mmpd+0x34/0xb0 fs/ext4/mmp.c:255
__ext4_fill_super fs/ext4/super.c:5538 [inline]
ext4_fill_super+0x8766/0xc070 fs/ext4/super.c:5587
get_tree_bdev+0x398/0x680 fs/super.c:1292
vfs_get_tree+0x7f/0x2c0 fs/super.c:1497
do_new_mount fs/namespace.c:3040 [inline]
path_mount+0x7e8/0x1a40 fs/namespace.c:3370
do_mount fs/namespace.c:3383 [inline]
__do_sys_mount fs/namespace.c:3591 [inline]
__se_sys_mount fs/namespace.c:3568 [inline]
__x64_sys_mount+0x1f5/0x260 fs/namespace.c:3568
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0x80 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x467afa
RSP: 002b:00007f5b237d2fa8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 0000000020000380 RCX: 0000000000467afa
RDX: 0000000020000000 RSI: 00000000200000c0 RDI: 00007f5b237d3000
RBP: 00007f5b237d3040 R08: 00007f5b237d3040 R09: 0000000020000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000020000000
R13: 00000000200000c0 R14: 00007f5b237d3000 R15: 0000000020000200
Showing all locks held in the system:
1 lock held by khungtaskd/28:
#0: ffffffff8ad76660 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:6467
2 locks held by getty/3314:
#0: ffff888148b42098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x1f/0x70 drivers/tty/tty_ldisc.c:244
#1: ffffc90002a662e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x9d7/0xed0 drivers/tty/n_tty.c:2075
1 lock held by syz-executor.2/4021:
#0: ffff888077bf00e0 (&type->s_umount_key#27/1){+.+.}-{3:3}, at: alloc_super+0x192/0x9e0 fs/super.c:228
1 lock held by syz-executor.3/4040:
#0: ffff88801e0180e0 (&type->s_umount_key#27/1){+.+.}-{3:3}, at: alloc_super+0x192/0x9e0 fs/super.c:228
=============================================
NMI backtrace for cpu 1
CPU: 1 PID: 28 Comm: khungtaskd Not tainted 5.18.0-rc2-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:111
nmi_trigger_cpumask_backtrace+0x140/0x170 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:212 [inline]
watchdog+0x88c/0xbf0 kernel/hung_task.c:369
kthread+0x299/0x340 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 54 Comm: kworker/u4:2 Not tainted 5.18.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: bat_events batadv_nc_worker
RIP: 0010:find_held_lock+0xbc/0x110 kernel/locking/lockdep.c:5153
Code: 0f b6 5b 21 48 89 f8 48 89 fa 48 c1 e8 03 83 e2 07 0f b6 04 28 38 d0 7f 04 84 c0 75 4e 41 32 5c 24 21 83 e3 60 74 94 45 31 e4 <48> b8 00 00 00 00 00 fc ff df 4c 89 f2 48 c1 ea 03 0f b6 14 02 4c
RSP: 0018:ffffc90000bf7b88 EFLAGS: 00000002
RAX: 0000000000000001 RBX: 0000000000000003 RCX: ffffc90000bf7c10
RDX: 0000000000000003 RSI: ffffffff8ad76660 RDI: ffff8880159ec3f0
RBP: 1ffff9200017ef7a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000001 R12: ffff8880159ec3f0
R13: ffffffff8ad76660 R14: ffffc90000bf7c10 R15: 0000000000000002
FS: 0000000000000000(0000) GS:ffff8880b9e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055ef510b79f0 CR3: 000000000aa8e000 CR4: 0000000000350ef0
Call Trace:
__lock_release kernel/locking/lockdep.c:5316 [inline]
lock_release+0x1f2/0x720 kernel/locking/lockdep.c:5661
rcu_lock_release include/linux/rcupdate.h:273 [inline]
rcu_read_unlock include/linux/rcupdate.h:727 [inline]
batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:412 [inline]
batadv_nc_worker+0x668/0xd70 net/batman-adv/network-coding.c:719
process_one_work+0x865/0x13d0 kernel/workqueue.c:2289
worker_thread+0x598/0xec0 kernel/workqueue.c:2436
kthread+0x299/0x340 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298
----------------
Code disassembly (best guess):
0: 0f b6 5b 21 movzbl 0x21(%rbx),%ebx
4: 48 89 f8 mov %rdi,%rax
7: 48 89 fa mov %rdi,%rdx
a: 48 c1 e8 03 shr $0x3,%rax
e: 83 e2 07 and $0x7,%edx
11: 0f b6 04 28 movzbl (%rax,%rbp,1),%eax
15: 38 d0 cmp %dl,%al
17: 7f 04 jg 0x1d
19: 84 c0 test %al,%al
1b: 75 4e jne 0x6b
1d: 41 32 5c 24 21 xor 0x21(%r12),%bl
22: 83 e3 60 and $0x60,%ebx
25: 74 94 je 0xffffffbb
27: 45 31 e4 xor %r12d,%r12d
* 2a: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax <-- trapping instruction
31: fc ff df
34: 4c 89 f2 mov %r14,%rdx
37: 48 c1 ea 03 shr $0x3,%rdx
3b: 0f b6 14 02 movzbl (%rdx,%rax,1),%edx
3f: 4c rex.WR