INFO: rcu detected stall in sendfile64 (2)

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 78d697fc Linux 4.14.172
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=16fb0819e00000
kernel config: https://syzkaller.appspot.com/x/.config?x=31ad682bcda9b93f
dashboard link: https://syzkaller.appspot.com/bug?extid=f7bb058842149b6d5423
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+f7bb05...@syzkaller.appspotmail.com

attempt to access beyond end of device
loop5: rw=2049, want=78, limit=63
attempt to access beyond end of device
loop5: rw=2049, want=79, limit=63
attempt to access beyond end of device
INFO: rcu_sched detected stalls on CPUs/tasks:
(detected by 0, t=10502 jiffies, g=2521, c=2520, q=8)
All QSes seen, last rcu_sched kthread activity 10498 (4294973243-4294962745), jiffies_till_next_fqs=1, root ->qsmask 0x0
syz-executor.4 R running task 27440 9504 7349 0x00000000
Call Trace:
<IRQ>
sched_show_task kernel/sched/core.c:5168 [inline]
sched_show_task.cold+0x2e3/0x347 kernel/sched/core.c:5143
print_other_cpu_stall kernel/rcu/tree.c:1501 [inline]
check_cpu_stall kernel/rcu/tree.c:1616 [inline]
__rcu_pending kernel/rcu/tree.c:3390 [inline]
rcu_pending kernel/rcu/tree.c:3452 [inline]
rcu_check_callbacks.cold+0xd3f/0xdaa kernel/rcu/tree.c:2792
update_process_times+0x29/0x60 kernel/time/timer.c:1590
tick_sched_handle+0x7d/0x150 kernel/time/tick-sched.c:165
tick_sched_timer+0x3e/0x120 kernel/time/tick-sched.c:1223
__run_hrtimer kernel/time/hrtimer.c:1223 [inline]
__hrtimer_run_queues+0x25c/0xbb0 kernel/time/hrtimer.c:1287
hrtimer_interrupt+0x1e6/0x5e0 kernel/time/hrtimer.c:1321
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1075 [inline]
smp_apic_timer_interrupt+0x117/0x5e0 arch/x86/kernel/apic/apic.c:1100
apic_timer_interrupt+0x8f/0xa0 arch/x86/entry/entry_64.S:792
</IRQ>
RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:779 [inline]
RIP: 0010:kfree+0xf4/0x260 mm/slab.c:3816
RSP: 0018:ffff88804ad0fa00 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff10
RAX: 0000000000000007 RBX: 0000000000000286 RCX: 1ffff11012aa79cc
RDX: 0000000000000000 RSI: ffff88809553ce40 RDI: 0000000000000286
RBP: ffff88808a3d0200 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff88812fe567c0
R13: ffffffff81960da4 R14: ffff88809e8b6d00 R15: 0000000000000000
iter_file_splice_write+0x464/0xa10 fs/splice.c:776
do_splice_from fs/splice.c:851 [inline]
direct_splice_actor+0x115/0x160 fs/splice.c:1018
splice_direct_to_actor+0x27e/0x730 fs/splice.c:973
do_splice_direct+0x164/0x210 fs/splice.c:1061
do_sendfile+0x469/0xaf0 fs/read_write.c:1441
SYSC_sendfile64 fs/read_write.c:1496 [inline]
SyS_sendfile64+0x9b/0x110 fs/read_write.c:1488
do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x45c479
RSP: 002b:00007f76b6bdcc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007f76b6bdd6d4 RCX: 000000000045c479
RDX: 00000000200001c0 RSI: 0000000000000003 RDI: 0000000000000003
RBP: 000000000076bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 00008080fffffffe R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000008d1 R14: 00000000004cb364 R15: 000000000076bf2c
rcu_sched kthread starved for 10498 jiffies! g2521 c2520 f0x2 RCU_GP_WAIT_FQS(3) ->state=0x0 ->cpu=0
rcu_sched R running task 29920 9 2 0x80000000
Call Trace:
schedule+0x8d/0x1b0 kernel/sched/core.c:3428
schedule_timeout+0x43c/0xe40 kernel/time/timer.c:1746
rcu_gp_kthread+0xb8e/0x1ce0 kernel/rcu/tree.c:2255
kthread+0x30d/0x420 kernel/kthread.c:232
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404
INFO: rcu_preempt detected stalls on CPUs/tasks:
(detected by 0, t=10537 jiffies, g=3355, c=3354, q=498)
All QSes seen, last rcu_preempt kthread activity 10537 (4294973281-4294962744), jiffies_till_next_fqs=1, root ->qsmask 0x0
syz-executor.4 R running task 27440 9504 7349 0x00000000
Call Trace:
<IRQ>
sched_show_task kernel/sched/core.c:5168 [inline]
sched_show_task.cold+0x2e3/0x347 kernel/sched/core.c:5143
print_other_cpu_stall kernel/rcu/tree.c:1501 [inline]
check_cpu_stall kernel/rcu/tree.c:1616 [inline]
__rcu_pending kernel/rcu/tree.c:3390 [inline]
rcu_pending kernel/rcu/tree.c:3452 [inline]
rcu_check_callbacks.cold+0xd3f/0xdaa kernel/rcu/tree.c:2792
update_process_times+0x29/0x60 kernel/time/timer.c:1590
tick_sched_handle+0x7d/0x150 kernel/time/tick-sched.c:165
tick_sched_timer+0x3e/0x120 kernel/time/tick-sched.c:1223
__run_hrtimer kernel/time/hrtimer.c:1223 [inline]
__hrtimer_run_queues+0x25c/0xbb0 kernel/time/hrtimer.c:1287
hrtimer_interrupt+0x1e6/0x5e0 kernel/time/hrtimer.c:1321
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1075 [inline]
smp_apic_timer_interrupt+0x117/0x5e0 arch/x86/kernel/apic/apic.c:1100
apic_timer_interrupt+0x8f/0xa0 arch/x86/entry/entry_64.S:792
</IRQ>
RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:779 [inline]
RIP: 0010:kfree+0xf4/0x260 mm/slab.c:3816
RSP: 0018:ffff88804ad0fa00 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff10
RAX: 0000000000000007 RBX: 0000000000000286 RCX: 1ffff11012aa79cc
RDX: 0000000000000000 RSI: ffff88809553ce40 RDI: 0000000000000286
RBP: ffff88808a3d0200 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff88812fe567c0
R13: ffffffff81960da4 R14: ffff88809e8b6d00 R15: 0000000000000000
iter_file_splice_write+0x464/0xa10 fs/splice.c:776
do_splice_from fs/splice.c:851 [inline]
direct_splice_actor+0x115/0x160 fs/splice.c:1018
splice_direct_to_actor+0x27e/0x730 fs/splice.c:973
do_splice_direct+0x164/0x210 fs/splice.c:1061
do_sendfile+0x469/0xaf0 fs/read_write.c:1441
SYSC_sendfile64 fs/read_write.c:1496 [inline]
SyS_sendfile64+0x9b/0x110 fs/read_write.c:1488
do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x45c479
RSP: 002b:00007f76b6bdcc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007f76b6bdd6d4 RCX: 000000000045c479
RDX: 00000000200001c0 RSI: 0000000000000003 RDI: 0000000000000003
RBP: 000000000076bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 00008080fffffffe R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000008d1 R14: 00000000004cb364 R15: 000000000076bf2c
rcu_preempt kthread starved for 10537 jiffies! g3355 c3354 f0x2 RCU_GP_WAIT_FQS(3) ->state=0x0 ->cpu=0
rcu_preempt R running task 29920 8 2 0x80000000
Call Trace:
schedule+0x8d/0x1b0 kernel/sched/core.c:3428
schedule_timeout+0x43c/0xe40 kernel/time/timer.c:1746
rcu_gp_kthread+0xb8e/0x1ce0 kernel/rcu/tree.c:2255
kthread+0x30d/0x420 kernel/kthread.c:232
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404


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[syzbot]

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