INFO: rcu detected stall in sys_sendfile64 (2)

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: d183c8e2 Linux 4.19.98
git tree: linux-4.19.y
console output: https://syzkaller.appspot.com/x/log.txt?x=149b4695e00000
kernel config: https://syzkaller.appspot.com/x/.config?x=2ec5d533b79bf93
dashboard link: https://syzkaller.appspot.com/bug?extid=5b31ebf58ec2861eb238
compiler: gcc (GCC) 9.0.0 20181231 (experimental)

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+5b31eb...@syzkaller.appspotmail.com

audit: type=1804 audit(1580054635.143:688): pid=4136 uid=0 auid=4294967295 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 op=invalid_pcr cause=open_writers comm="syz-executor.4" name="bus" dev="sda1" ino=17457 res=1
rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 1-....: (1191 ticks this GP) idle=23a/1/0x4000000000000002 softirq=158711/158711 fqs=2
rcu: (t=10500 jiffies g=215317 q=723)
rcu: rcu_preempt kthread starved for 1873 jiffies! g215317 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=0
rcu: RCU grace-period kthread stack dump:
rcu_preempt I29008 10 2 0x80000000
Call Trace:
context_switch kernel/sched/core.c:2826 [inline]
__schedule+0x866/0x1dc0 kernel/sched/core.c:3515
schedule+0x92/0x1c0 kernel/sched/core.c:3559
schedule_timeout+0x4db/0xfc0 kernel/time/timer.c:1806
rcu_gp_kthread+0xd5c/0x2190 kernel/rcu/tree.c:2202
kthread+0x354/0x420 kernel/kthread.c:246
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415
NMI backtrace for cpu 1
CPU: 1 PID: 4129 Comm: syz-executor.0 Not tainted 4.19.98-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
<IRQ>
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x197/0x210 lib/dump_stack.c:118
nmi_cpu_backtrace.cold+0x63/0xa4 lib/nmi_backtrace.c:101
nmi_trigger_cpumask_backtrace+0x1b0/0x1f8 lib/nmi_backtrace.c:62
arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline]
rcu_dump_cpu_stacks+0x189/0x1d5 kernel/rcu/tree.c:1340
print_cpu_stall kernel/rcu/tree.c:1478 [inline]
check_cpu_stall kernel/rcu/tree.c:1550 [inline]
__rcu_pending kernel/rcu/tree.c:3293 [inline]
rcu_pending kernel/rcu/tree.c:3336 [inline]
rcu_check_callbacks.cold+0x5e3/0xd90 kernel/rcu/tree.c:2682
update_process_times+0x32/0x80 kernel/time/timer.c:1638
tick_sched_handle+0xa2/0x190 kernel/time/tick-sched.c:168
tick_sched_timer+0x47/0x130 kernel/time/tick-sched.c:1278
__run_hrtimer kernel/time/hrtimer.c:1401 [inline]
__hrtimer_run_queues+0x33b/0xdc0 kernel/time/hrtimer.c:1463
hrtimer_interrupt+0x314/0x770 kernel/time/hrtimer.c:1521
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1067 [inline]
smp_apic_timer_interrupt+0x111/0x550 arch/x86/kernel/apic/apic.c:1092
apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:893
</IRQ>
RIP: 0010:__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:169 [inline]
RIP: 0010:_raw_spin_unlock_irq+0x54/0x90 kernel/locking/spinlock.c:192
Code: c0 d8 5b f2 88 48 ba 00 00 00 00 00 fc ff df 48 c1 e8 03 80 3c 10 00 75 33 48 83 3d 6d 7b 9c 01 00 74 20 fb 66 0f 1f 44 00 00 <bf> 01 00 00 00 e8 b2 ff f2 f9 65 8b 05 4b 0d ac 78 85 c0 74 06 41
RSP: 0018:ffff8880724e7630 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff13
RAX: 1ffffffff11e4b7b RBX: ffff8880790ea480 RCX: 1ffff1100f21d5a4
RDX: dffffc0000000000 RSI: ffff8880790ead00 RDI: ffff8880790eacfc
RBP: ffff8880724e7638 R08: ffff8880790ea480 R09: ffff8880790ead20
R10: 0000000000000000 R11: 0000000000000000 R12: ffff8880ae92c240
R13: ffff888092c38300 R14: 0000000000000000 R15: 0000000000000102
finish_lock_switch kernel/sched/core.c:2576 [inline]
finish_task_switch+0x146/0x7c0 kernel/sched/core.c:2676
context_switch kernel/sched/core.c:2829 [inline]
__schedule+0x86e/0x1dc0 kernel/sched/core.c:3515
schedule+0x92/0x1c0 kernel/sched/core.c:3559
io_schedule+0x1c/0x70 kernel/sched/core.c:5182
wait_on_page_bit_common mm/filemap.c:1123 [inline]
wait_on_page_bit_killable mm/filemap.c:1163 [inline]
wait_on_page_locked_killable include/linux/pagemap.h:537 [inline]
generic_file_buffered_read mm/filemap.c:2138 [inline]
generic_file_read_iter+0xee3/0x2b90 mm/filemap.c:2385
ext4_file_read_iter+0x180/0x3c0 fs/ext4/file.c:77
call_read_iter include/linux/fs.h:1814 [inline]
generic_file_splice_read+0x42c/0x750 fs/splice.c:308
do_splice_to+0x127/0x180 fs/splice.c:881
splice_direct_to_actor+0x2d3/0x970 fs/splice.c:959
do_splice_direct+0x1da/0x2a0 fs/splice.c:1068
do_sendfile+0x597/0xce0 fs/read_write.c:1447
__do_sys_sendfile64 fs/read_write.c:1508 [inline]
__se_sys_sendfile64 fs/read_write.c:1494 [inline]
__x64_sys_sendfile64+0x1dd/0x220 fs/read_write.c:1494
do_syscall_64+0xfd/0x620 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45b349
Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f741a328c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007f741a3296d4 RCX: 000000000045b349
RDX: 0000000000000000 RSI: 0000000000000008 RDI: 0000000000000005
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 00008400fffffffb R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000008c9 R14: 00000000004ca1ed R15: 000000000075bf2c


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[syzbot]

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