INFO: rcu detected stall in generic_file_write_iter (4)

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: fdfa3a67 Merge tag 'scsi-misc' of git://git.kernel.org/pub..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=104ffba5e00000
kernel config: https://syzkaller.appspot.com/x/.config?x=1910a1dea657830a
dashboard link: https://syzkaller.appspot.com/bug?extid=415020d172cd05f3e283
compiler: clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81)
CC: [and...@fb.com a...@kernel.org b...@vger.kernel.org cgr...@vger.kernel.org dan...@iogearbox.net han...@cmpxchg.org ka...@fb.com linux-...@vger.kernel.org liz...@huawei.com net...@vger.kernel.org songliu...@fb.com t...@kernel.org y...@fb.com]

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+415020...@syzkaller.appspotmail.com

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
(detected by 1, t=10502 jiffies, g=180313, q=37)
rcu: All QSes seen, last rcu_preempt kthread activity 10494 (4295069428-4295058934), jiffies_till_next_fqs=1, root ->qsmask 0x0
syz-executor.5 R running task 25144 24667 24666 0x00004002
Call Trace:
<IRQ>
sched_show_task+0x411/0x560 kernel/sched/core.c:5954
print_other_cpu_stall kernel/rcu/tree_stall.h:430 [inline]
check_cpu_stall kernel/rcu/tree_stall.h:558 [inline]
rcu_pending kernel/rcu/tree.c:3030 [inline]
rcu_sched_clock_irq+0x188c/0x1aa0 kernel/rcu/tree.c:2276
update_process_times+0x12d/0x180 kernel/time/timer.c:1726
tick_sched_handle kernel/time/tick-sched.c:171 [inline]
tick_sched_timer+0x263/0x420 kernel/time/tick-sched.c:1314
__run_hrtimer kernel/time/hrtimer.c:1517 [inline]
__hrtimer_run_queues+0x3f3/0x840 kernel/time/hrtimer.c:1579
hrtimer_interrupt+0x37c/0xda0 kernel/time/hrtimer.c:1641
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1110 [inline]
smp_apic_timer_interrupt+0x109/0x280 arch/x86/kernel/apic/apic.c:1135
apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829
</IRQ>
RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:752 [inline]
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:160 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0xa8/0xe0 kernel/locking/spinlock.c:191
Code: b9 00 00 00 00 00 fc ff df 80 3c 08 00 74 0c 48 c7 c7 d0 d2 2a 89 e8 d7 c4 9b f9 48 83 3d 9f 72 12 01 00 74 2d 4c 89 f7 57 9d <0f> 1f 44 00 00 bf 01 00 00 00 e8 69 c7 3a f9 65 8b 05 7e bd e9 77
RSP: 0018:ffffc9000864f798 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff13
RAX: 1ffffffff1255a5a RBX: ffffffff892e49c0 RCX: dffffc0000000000
RDX: 0000000000000000 RSI: 0000000000000008 RDI: 0000000000000282
RBP: ffffc9000864f7a8 R08: ffff8880556b4dd8 R09: fffffbfff1406327
R10: fffffbfff1406327 R11: 0000000000000000 R12: 0000000100018ef3
R13: ffff8880992aa530 R14: 0000000000000282 R15: 1ffff110132554a5
spin_unlock_irqrestore include/linux/spinlock.h:393 [inline]
cgroup_file_notify+0x184/0x1a0 kernel/cgroup/cgroup.c:4099
memcg_memory_event include/linux/memcontrol.h:779 [inline]
try_charge+0x4f2/0x18a0 mm/memcontrol.c:2453
mem_cgroup_try_charge+0x216/0x550 mm/memcontrol.c:6367
mem_cgroup_try_charge_delay+0x25/0xa0 mm/memcontrol.c:6382
shmem_getpage_gfp+0x1246/0x2f80 mm/shmem.c:1872
shmem_getpage mm/shmem.c:154 [inline]
shmem_write_begin+0xcb/0x1b0 mm/shmem.c:2488
generic_perform_write+0x23d/0x4f0 mm/filemap.c:3287
__generic_file_write_iter+0x235/0x500 mm/filemap.c:3416
generic_file_write_iter+0x4b1/0x660 mm/filemap.c:3448
call_write_iter include/linux/fs.h:1901 [inline]
new_sync_write fs/read_write.c:483 [inline]
__vfs_write+0x5a1/0x740 fs/read_write.c:496
vfs_write+0x270/0x580 fs/read_write.c:558
ksys_pwrite64 fs/read_write.c:665 [inline]
__do_sys_pwrite64 fs/read_write.c:675 [inline]
__se_sys_pwrite64 fs/read_write.c:672 [inline]
__x64_sys_pwrite64+0x162/0x1d0 fs/read_write.c:672
do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x415197
Code: 12 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 a1 18 00 00 c3 48 83 ec 08 e8 a7 f9 ff ff 48 89 04 24 49 89 ca b8 12 00 00 00 0f 05 <48> 8b 3c 24 48 89 c2 e8 ed f9 ff ff 48 89 d0 48 83 c4 08 48 3d 01
RSP: 002b:00007fae5e6f7a60 EFLAGS: 00000246 ORIG_RAX: 0000000000000012
RAX: ffffffffffffffda RBX: 00007fae5e6f86d4 RCX: 0000000000415197
RDX: 0000000008100000 RSI: 0000000020000680 RDI: 0000000000000009
RBP: 000000000075c070 R08: fe03f80fe03f80ff R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000ba5 R14: 00000000004cc7cf R15: 000000000075c07c
rcu: rcu_preempt kthread starved for 10494 jiffies! g180313 f0x2 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
rcu: RCU grace-period kthread stack dump:
rcu_preempt R running task 28736 10 2 0x80004000
Call Trace:
context_switch kernel/sched/core.c:3386 [inline]
__schedule+0x87f/0xcd0 kernel/sched/core.c:4082
schedule+0x188/0x210 kernel/sched/core.c:4156
schedule_timeout+0x14f/0x240 kernel/time/timer.c:1895
rcu_gp_fqs_loop kernel/rcu/tree.c:1658 [inline]
rcu_gp_kthread+0xe8d/0x17e0 kernel/rcu/tree.c:1818
kthread+0x332/0x350 kernel/kthread.c:255
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.