Hello,
syzbot found the following crash on:
HEAD commit: 8f3d9f35 Linux 5.7-rc1
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=115720c3e00000
kernel config: https://syzkaller.appspot.com/x/.config?x=5d351a1019ed81a2
dashboard link: https://syzkaller.appspot.com/bug?extid=66243bb7126c410cefe6
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: [email protected]
rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 0-....: (10500 ticks this GP) idle=57e/1/0x4000000000000002 softirq=44329/44329 fqs=5245
(t=10502 jiffies g=79401 q=2096)
NMI backtrace for cpu 0
CPU: 0 PID: 23184 Comm: syz-executor.5 Not tainted 5.7.0-rc1-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+0x188/0x20d lib/dump_stack.c:118
nmi_cpu_backtrace.cold+0x70/0xb1 lib/nmi_backtrace.c:101
nmi_trigger_cpumask_backtrace+0x231/0x27e lib/nmi_backtrace.c:62
trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline]
rcu_dump_cpu_stacks+0x19b/0x1e5 kernel/rcu/tree_stall.h:254
print_cpu_stall kernel/rcu/tree_stall.h:475 [inline]
check_cpu_stall kernel/rcu/tree_stall.h:549 [inline]
rcu_pending kernel/rcu/tree.c:3225 [inline]
rcu_sched_clock_irq.cold+0x55d/0xcfa kernel/rcu/tree.c:2296
update_process_times+0x25/0x60 kernel/time/timer.c:1727
tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:176
tick_sched_timer+0x4e/0x140 kernel/time/tick-sched.c:1320
__run_hrtimer kernel/time/hrtimer.c:1520 [inline]
__hrtimer_run_queues+0x5ca/0xed0 kernel/time/hrtimer.c:1584
hrtimer_interrupt+0x312/0x770 kernel/time/hrtimer.c:1646
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1113 [inline]
smp_apic_timer_interrupt+0x15b/0x600 arch/x86/kernel/apic/apic.c:1138
apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829
</IRQ>
RIP: 0010:io_ring_ctx_wait_and_kill+0x98/0x5a0 fs/io_uring.c:7301
Code: 01 00 00 4d 89 f4 48 b8 00 00 00 00 00 fc ff df 4c 89 ed 49 c1 ec 03 48 c1 ed 03 49 01 c4 48 01 c5 eb 1c e8 3a ea 9d ff f3 90 <41> 80 3c 24 00 0f 85 53 04 00 00 48 83 bb 10 01 00 00 00 74 21 e8
RSP: 0018:ffffc9000897fdf0 EFLAGS: 00000293 ORIG_RAX: ffffffffffffff13
RAX: ffff888024082080 RBX: ffff88808df8e000 RCX: 1ffff9200112ffab
RDX: 0000000000000000 RSI: ffffffff81d549c6 RDI: ffff88808df8e300
RBP: ffffed1011bf1c2c R08: 0000000000000001 R09: ffffed1011bf1c61
R10: ffff88808df8e307 R11: ffffed1011bf1c60 R12: ffffed1011bf1c22
R13: ffff88808df8e160 R14: ffff88808df8e110 R15: ffffffff81d54ed0
io_uring_release+0x3e/0x50 fs/io_uring.c:7324
__fput+0x33e/0x880 fs/file_table.c:280
task_work_run+0xf4/0x1b0 kernel/task_work.c:123
tracehook_notify_resume include/linux/tracehook.h:188 [inline]
exit_to_usermode_loop+0x2fa/0x360 arch/x86/entry/common.c:165
prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline]
syscall_return_slowpath arch/x86/entry/common.c:279 [inline]
do_syscall_64+0x6b1/0x7d0 arch/x86/entry/common.c:305
entry_SYSCALL_64_after_hwframe+0x49/0xb3
RIP: 0033:0x416421
Code: 75 14 b8 03 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 04 1b 00 00 c3 48 83 ec 08 e8 0a fc ff ff 48 89 04 24 b8 03 00 00 00 0f 05 <48> 8b 3c 24 48 89 c2 e8 53 fc ff ff 48 89 d0 48 83 c4 08 48 3d 01
RSP: 002b:00007ffc3c9f63d0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000004 RCX: 0000000000416421
RDX: 00000000000f4240 RSI: 0000000000000081 RDI: 0000000000000003
RBP: 0000000000000000 R08: 0000000000000000 R09: 01ffffffffffffff
R10: 0000000000770b20 R11: 0000000000000293 R12: 000000000076bfa0
R13: 0000000000770b30 R14: 0000000000000001 R15: 000000000076bfac
---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at [email protected].
syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
On 4/18/20 10:06 PM, Hillf Danton wrote:
>
> Sat, 18 Apr 2020 11:59:13 -0700
>>
>> syzbot found the following crash on:
>>
>> HEAD commit: 8f3d9f35 Linux 5.7-rc1
>> git tree: upstream
>> console output: https://syzkaller.appspot.com/x/log.txt?x=115720c3e00000
>> kernel config: https://syzkaller.appspot.com/x/.config?x=5d351a1019ed81a2
>> dashboard link: https://syzkaller.appspot.com/bug?extid=66243bb7126c410cefe6
>> 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: [email protected]
>>
>> rcu: INFO: rcu_preempt self-detected stall on CPU
>> rcu: 0-....: (10500 ticks this GP) idle=57e/1/0x4000000000000002 softirq=44329/44329 fqs=5245
>> (t=10502 jiffies g=79401 q=2096)
>> NMI backtrace for cpu 0
>> CPU: 0 PID: 23184 Comm: syz-executor.5 Not tainted 5.7.0-rc1-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+0x188/0x20d lib/dump_stack.c:118
>> nmi_cpu_backtrace.cold+0x70/0xb1 lib/nmi_backtrace.c:101
>> nmi_trigger_cpumask_backtrace+0x231/0x27e lib/nmi_backtrace.c:62
>> trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline]
>> rcu_dump_cpu_stacks+0x19b/0x1e5 kernel/rcu/tree_stall.h:254
>> print_cpu_stall kernel/rcu/tree_stall.h:475 [inline]
>> check_cpu_stall kernel/rcu/tree_stall.h:549 [inline]
>> rcu_pending kernel/rcu/tree.c:3225 [inline]
>> rcu_sched_clock_irq.cold+0x55d/0xcfa kernel/rcu/tree.c:2296
>> update_process_times+0x25/0x60 kernel/time/timer.c:1727
>> tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:176
>> tick_sched_timer+0x4e/0x140 kernel/time/tick-sched.c:1320
>> __run_hrtimer kernel/time/hrtimer.c:1520 [inline]
>> __hrtimer_run_queues+0x5ca/0xed0 kernel/time/hrtimer.c:1584
>> hrtimer_interrupt+0x312/0x770 kernel/time/hrtimer.c:1646
>> local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1113 [inline]
>> smp_apic_timer_interrupt+0x15b/0x600 arch/x86/kernel/apic/apic.c:1138
>> apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829
>> </IRQ>
>> RIP: 0010:io_ring_ctx_wait_and_kill+0x98/0x5a0 fs/io_uring.c:7301
>> Code: 01 00 00 4d 89 f4 48 b8 00 00 00 00 00 fc ff df 4c 89 ed 49 c1 ec 03 48 c1 ed 03 49 01 c4 48 01 c5 eb 1c e8 3a ea 9d ff f3 90 <41> 80 3c 24 00 0f 85 53 04 00 00 48 83 bb 10 01 00 00 00 74 21 e8
>> RSP: 0018:ffffc9000897fdf0 EFLAGS: 00000293 ORIG_RAX: ffffffffffffff13
>> RAX: ffff888024082080 RBX: ffff88808df8e000 RCX: 1ffff9200112ffab
>> RDX: 0000000000000000 RSI: ffffffff81d549c6 RDI: ffff88808df8e300
>> RBP: ffffed1011bf1c2c R08: 0000000000000001 R09: ffffed1011bf1c61
>> R10: ffff88808df8e307 R11: ffffed1011bf1c60 R12: ffffed1011bf1c22
>> R13: ffff88808df8e160 R14: ffff88808df8e110 R15: ffffffff81d54ed0
>> io_uring_release+0x3e/0x50 fs/io_uring.c:7324
>> __fput+0x33e/0x880 fs/file_table.c:280
>> task_work_run+0xf4/0x1b0 kernel/task_work.c:123
>> tracehook_notify_resume include/linux/tracehook.h:188 [inline]
>> exit_to_usermode_loop+0x2fa/0x360 arch/x86/entry/common.c:165
>> prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline]
>> syscall_return_slowpath arch/x86/entry/common.c:279 [inline]
>> do_syscall_64+0x6b1/0x7d0 arch/x86/entry/common.c:305
>> entry_SYSCALL_64_after_hwframe+0x49/0xb3
>
> Make io ring ctx's percpu_ref balanced.
>
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -5904,6 +5904,7 @@ static int io_submit_sqes(struct io_ring
> fail_req:
> io_cqring_add_event(req, err);
> io_double_put_req(req);
> + --submitted;
> break;
> }
Not sure this is right, need to look closer. But if we post a completion
event, the event has been consumed and should be accounted as such.
--
Jens Axboe
On Sun, Apr 19, 2020 at 12:06:26PM +0800, Hillf Danton wrote:
>
> Sat, 18 Apr 2020 11:59:13 -0700
> >
> > syzbot found the following crash on:
> >
> > HEAD commit: 8f3d9f35 Linux 5.7-rc1
> > git tree: upstream
> > console output: https://syzkaller.appspot.com/x/log.txt?x=115720c3e00000
> > kernel config: https://syzkaller.appspot.com/x/.config?x=5d351a1019ed81a2
> > dashboard link: https://syzkaller.appspot.com/bug?extid=66243bb7126c410cefe6
> > 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: [email protected]
> >
> > rcu: INFO: rcu_preempt self-detected stall on CPU
> > rcu: 0-....: (10500 ticks this GP) idle=57e/1/0x4000000000000002 softirq=44329/44329 fqs=5245
> > (t=10502 jiffies g=79401 q=2096)
> > NMI backtrace for cpu 0
> > CPU: 0 PID: 23184 Comm: syz-executor.5 Not tainted 5.7.0-rc1-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+0x188/0x20d lib/dump_stack.c:118
> > nmi_cpu_backtrace.cold+0x70/0xb1 lib/nmi_backtrace.c:101
> > nmi_trigger_cpumask_backtrace+0x231/0x27e lib/nmi_backtrace.c:62
> > trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline]
> > rcu_dump_cpu_stacks+0x19b/0x1e5 kernel/rcu/tree_stall.h:254
> > print_cpu_stall kernel/rcu/tree_stall.h:475 [inline]
> > check_cpu_stall kernel/rcu/tree_stall.h:549 [inline]
> > rcu_pending kernel/rcu/tree.c:3225 [inline]
> > rcu_sched_clock_irq.cold+0x55d/0xcfa kernel/rcu/tree.c:2296
> > update_process_times+0x25/0x60 kernel/time/timer.c:1727
> > tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:176
> > tick_sched_timer+0x4e/0x140 kernel/time/tick-sched.c:1320
> > __run_hrtimer kernel/time/hrtimer.c:1520 [inline]
> > __hrtimer_run_queues+0x5ca/0xed0 kernel/time/hrtimer.c:1584
> > hrtimer_interrupt+0x312/0x770 kernel/time/hrtimer.c:1646
> > local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1113 [inline]
> > smp_apic_timer_interrupt+0x15b/0x600 arch/x86/kernel/apic/apic.c:1138
> > apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829
> > </IRQ>
> > RIP: 0010:io_ring_ctx_wait_and_kill+0x98/0x5a0 fs/io_uring.c:7301
> > Code: 01 00 00 4d 89 f4 48 b8 00 00 00 00 00 fc ff df 4c 89 ed 49 c1 ec 03 48 c1 ed 03 49 01 c4 48 01 c5 eb 1c e8 3a ea 9d ff f3 90 <41> 80 3c 24 00 0f 85 53 04 00 00 48 83 bb 10 01 00 00 00 74 21 e8
> > RSP: 0018:ffffc9000897fdf0 EFLAGS: 00000293 ORIG_RAX: ffffffffffffff13
> > RAX: ffff888024082080 RBX: ffff88808df8e000 RCX: 1ffff9200112ffab
> > RDX: 0000000000000000 RSI: ffffffff81d549c6 RDI: ffff88808df8e300
> > RBP: ffffed1011bf1c2c R08: 0000000000000001 R09: ffffed1011bf1c61
> > R10: ffff88808df8e307 R11: ffffed1011bf1c60 R12: ffffed1011bf1c22
> > R13: ffff88808df8e160 R14: ffff88808df8e110 R15: ffffffff81d54ed0
> > io_uring_release+0x3e/0x50 fs/io_uring.c:7324
> > __fput+0x33e/0x880 fs/file_table.c:280
> > task_work_run+0xf4/0x1b0 kernel/task_work.c:123
> > tracehook_notify_resume include/linux/tracehook.h:188 [inline]
> > exit_to_usermode_loop+0x2fa/0x360 arch/x86/entry/common.c:165
> > prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline]
> > syscall_return_slowpath arch/x86/entry/common.c:279 [inline]
> > do_syscall_64+0x6b1/0x7d0 arch/x86/entry/common.c:305
> > entry_SYSCALL_64_after_hwframe+0x49/0xb3
>
> Make io ring ctx's percpu_ref balanced.
>
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -5904,6 +5904,7 @@ static int io_submit_sqes(struct io_ring
> fail_req:
> io_cqring_add_event(req, err);
> io_double_put_req(req);
> + --submitted;
> break;
> }
fs/io_uring.c
5880 for (i = 0; i < nr; i++) {
5881 const struct io_uring_sqe *sqe;
5882 struct io_kiocb *req;
5883 int err;
5884
5885 sqe = io_get_sqe(ctx);
5886 if (unlikely(!sqe)) {
5887 io_consume_sqe(ctx);
5888 break;
5889 }
5890 req = io_alloc_req(ctx, statep);
5891 if (unlikely(!req)) {
5892 if (!submitted)
5893 submitted = -EAGAIN;
5894 break;
5895 }
5896
5897 err = io_init_req(ctx, req, sqe, statep, async);
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
On the success path io_init_req() takes some references like:
get_cred(req->work.creds);
That one is probably buggy and should be put if the call to:
return io_req_set_file(state, req, fd, sqe_flags);
fails... But io_req_set_file() takes some other references if it
succeeds like percpu_ref_get(req->fixed_file_refs); and it's not clear
that those are released if io_submit_sqe() fails.
5898 io_consume_sqe(ctx);
5899 /* will complete beyond this point, count as submitted */
5900 submitted++;
5901
5902 if (unlikely(err)) {
5903 fail_req:
5904 io_cqring_add_event(req, err);
5905 io_double_put_req(req);
5906 break;
5907 }
5908
5909 trace_io_uring_submit_sqe(ctx, req->opcode, req->user_data,
5910 true, async);
5911 err = io_submit_sqe(req, sqe, statep, &link);
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
here
5912 if (err)
5913 goto fail_req;
5914 }
regards,
dan carpenter
On 4/20/2020 2:47 PM, Dan Carpenter wrote:
> On Sun, Apr 19, 2020 at 12:06:26PM +0800, Hillf Danton wrote:
>>
>> Sat, 18 Apr 2020 11:59:13 -0700
>>>
>>> syzbot found the following crash on:
>>>
>>> HEAD commit: 8f3d9f35 Linux 5.7-rc1
>>> git tree: upstream
>>> console output: https://syzkaller.appspot.com/x/log.txt?x=115720c3e00000
>>> kernel config: https://syzkaller.appspot.com/x/.config?x=5d351a1019ed81a2
>>> dashboard link: https://syzkaller.appspot.com/bug?extid=66243bb7126c410cefe6
>>> 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: [email protected]
>>>
>>> rcu: INFO: rcu_preempt self-detected stall on CPU
>>> rcu: 0-....: (10500 ticks this GP) idle=57e/1/0x4000000000000002 softirq=44329/44329 fqs=5245
>>> (t=10502 jiffies g=79401 q=2096)
>>> NMI backtrace for cpu 0
>>> CPU: 0 PID: 23184 Comm: syz-executor.5 Not tainted 5.7.0-rc1-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+0x188/0x20d lib/dump_stack.c:118
>>> nmi_cpu_backtrace.cold+0x70/0xb1 lib/nmi_backtrace.c:101
>>> nmi_trigger_cpumask_backtrace+0x231/0x27e lib/nmi_backtrace.c:62
>>> trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline]
>>> rcu_dump_cpu_stacks+0x19b/0x1e5 kernel/rcu/tree_stall.h:254
>>> print_cpu_stall kernel/rcu/tree_stall.h:475 [inline]
>>> check_cpu_stall kernel/rcu/tree_stall.h:549 [inline]
>>> rcu_pending kernel/rcu/tree.c:3225 [inline]
>>> rcu_sched_clock_irq.cold+0x55d/0xcfa kernel/rcu/tree.c:2296
>>> update_process_times+0x25/0x60 kernel/time/timer.c:1727
>>> tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:176
>>> tick_sched_timer+0x4e/0x140 kernel/time/tick-sched.c:1320
>>> __run_hrtimer kernel/time/hrtimer.c:1520 [inline]
>>> __hrtimer_run_queues+0x5ca/0xed0 kernel/time/hrtimer.c:1584
>>> hrtimer_interrupt+0x312/0x770 kernel/time/hrtimer.c:1646
>>> local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1113 [inline]
>>> smp_apic_timer_interrupt+0x15b/0x600 arch/x86/kernel/apic/apic.c:1138
>>> apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829
>>> </IRQ>
>>> RIP: 0010:io_ring_ctx_wait_and_kill+0x98/0x5a0 fs/io_uring.c:7301
>>> Code: 01 00 00 4d 89 f4 48 b8 00 00 00 00 00 fc ff df 4c 89 ed 49 c1 ec 03 48 c1 ed 03 49 01 c4 48 01 c5 eb 1c e8 3a ea 9d ff f3 90 <41> 80 3c 24 00 0f 85 53 04 00 00 48 83 bb 10 01 00 00 00 74 21 e8
>>> RSP: 0018:ffffc9000897fdf0 EFLAGS: 00000293 ORIG_RAX: ffffffffffffff13
>>> RAX: ffff888024082080 RBX: ffff88808df8e000 RCX: 1ffff9200112ffab
>>> RDX: 0000000000000000 RSI: ffffffff81d549c6 RDI: ffff88808df8e300
>>> RBP: ffffed1011bf1c2c R08: 0000000000000001 R09: ffffed1011bf1c61
>>> R10: ffff88808df8e307 R11: ffffed1011bf1c60 R12: ffffed1011bf1c22
>>> R13: ffff88808df8e160 R14: ffff88808df8e110 R15: ffffffff81d54ed0
>>> io_uring_release+0x3e/0x50 fs/io_uring.c:7324
>>> __fput+0x33e/0x880 fs/file_table.c:280
>>> task_work_run+0xf4/0x1b0 kernel/task_work.c:123
>>> tracehook_notify_resume include/linux/tracehook.h:188 [inline]
>>> exit_to_usermode_loop+0x2fa/0x360 arch/x86/entry/common.c:165
>>> prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline]
>>> syscall_return_slowpath arch/x86/entry/common.c:279 [inline]
>>> do_syscall_64+0x6b1/0x7d0 arch/x86/entry/common.c:305
>>> entry_SYSCALL_64_after_hwframe+0x49/0xb3
>>
>> Make io ring ctx's percpu_ref balanced.
>>
>> --- a/fs/io_uring.c
>> +++ b/fs/io_uring.c
>> @@ -5904,6 +5904,7 @@ static int io_submit_sqes(struct io_ring
>> fail_req:
>> io_cqring_add_event(req, err);
>> io_double_put_req(req);
>> + --submitted;
>> break;
>> }
>
>
> fs/io_uring.c
> 5880 for (i = 0; i < nr; i++) {
> 5881 const struct io_uring_sqe *sqe;
> 5882 struct io_kiocb *req;
> 5883 int err;
> 5884
> 5885 sqe = io_get_sqe(ctx);
> 5886 if (unlikely(!sqe)) {
> 5887 io_consume_sqe(ctx);
> 5888 break;
> 5889 }
> 5890 req = io_alloc_req(ctx, statep);
> 5891 if (unlikely(!req)) {
> 5892 if (!submitted)
> 5893 submitted = -EAGAIN;
> 5894 break;
> 5895 }
> 5896
> 5897 err = io_init_req(ctx, req, sqe, statep, async);
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> On the success path io_init_req() takes some references like:
>
> get_cred(req->work.creds);
If a req have got into io_init_req(), than it'll be put at some point
with io_put_req(). io_req_work_drop_env() called from there will clean
up req->work.creds.
>
> That one is probably buggy and should be put if the call to:
>
> return io_req_set_file(state, req, fd, sqe_flags);
>
> fails... But io_req_set_file() takes some other references if it
> succeeds like percpu_ref_get(req->fixed_file_refs); and it's not clear
> that those are released if io_submit_sqe() fails.
The same should happen with req->fixed_file_refs, though I don't
remember in details.
>
> 5898 io_consume_sqe(ctx);
> 5899 /* will complete beyond this point, count as submitted */
> 5900 submitted++;
Regarding, "--submitted" patch -- we take 1 ctx->refs per request, which
is put in io_put_req(). So after a request passes the line above (5900),
it's ref will be eventually dropped in io_put_req() and friends.
And it's a bit more peculiar because io_submit_sqes() batch-takes N refs
first, and then puts unused back at the end.
> 5901
> 5902 if (unlikely(err)) {
> 5903 fail_req:
> 5904 io_cqring_add_event(req, err);
> 5905 io_double_put_req(req);
> 5906 break;
> 5907 }
> 5908
> 5909 trace_io_uring_submit_sqe(ctx, req->opcode, req->user_data,
> 5910 true, async);
> 5911 err = io_submit_sqe(req, sqe, statep, &link);
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> here
>
> 5912 if (err)
> 5913 goto fail_req;
> 5914 }
>
> regards,
> dan carpenter
>
--
Pavel Begunkov
syzbot has found a reproducer for the following crash on:
HEAD commit: ac935d22 Add linux-next specific files for 20200415
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=13a38f0a100000
kernel config: https://syzkaller.appspot.com/x/.config?x=bc498783097e9019
dashboard link: https://syzkaller.appspot.com/bug?extid=66243bb7126c410cefe6
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=179b3b32100000
IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: [email protected]
rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 0-....: (10533 ticks this GP) idle=aea/1/0x4000000000000002 softirq=10553/10555 fqs=5249
(t=10501 jiffies g=12777 q=556)
NMI backtrace for cpu 0
CPU: 0 PID: 8729 Comm: syz-executor.3 Not tainted 5.7.0-rc1-next-20200415-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+0x188/0x20d lib/dump_stack.c:118
nmi_cpu_backtrace.cold+0x70/0xb1 lib/nmi_backtrace.c:101
nmi_trigger_cpumask_backtrace+0x231/0x27e lib/nmi_backtrace.c:62
trigger_single_cpu_backtrace include/linux/nmi.h:165 [inline]
rcu_dump_cpu_stacks+0x19b/0x1e5 kernel/rcu/tree_stall.h:254
print_cpu_stall kernel/rcu/tree_stall.h:475 [inline]
check_cpu_stall kernel/rcu/tree_stall.h:549 [inline]
rcu_pending kernel/rcu/tree.c:3225 [inline]
rcu_sched_clock_irq.cold+0x55d/0xd00 kernel/rcu/tree.c:2296
update_process_times+0x25/0x60 kernel/time/timer.c:1727
tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:176
tick_sched_timer+0x4e/0x140 kernel/time/tick-sched.c:1320
__run_hrtimer kernel/time/hrtimer.c:1520 [inline]
__hrtimer_run_queues+0x5ca/0xed0 kernel/time/hrtimer.c:1584
hrtimer_interrupt+0x312/0x770 kernel/time/hrtimer.c:1646
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1113 [inline]
smp_apic_timer_interrupt+0x15b/0x600 arch/x86/kernel/apic/apic.c:1138
apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829
</IRQ>
RIP: 0010:io_ring_ctx_wait_and_kill+0x98/0x5a0 fs/io_uring.c:7301
Code: 01 00 00 4d 89 f4 48 b8 00 00 00 00 00 fc ff df 4c 89 ed 49 c1 ec 03 48 c1 ed 03 49 01 c4 48 01 c5 eb 1c e8 ba 65 9d ff f3 90 <41> 80 3c 24 00 0f 85 53 04 00 00 48 83 bb 10 01 00 00 00 74 21 e8
RSP: 0018:ffffc900054d7a50 EFLAGS: 00000293 ORIG_RAX: ffffffffffffff13
RAX: ffff888097c14400 RBX: ffff8880963a0000 RCX: 1ffff92000a9af37
RDX: 0000000000000000 RSI: ffffffff81d5ced6 RDI: ffff8880963a0300
RBP: ffffed1012c7402c R08: 0000000000000001 R09: ffffed1012c74061
R10: ffff8880963a0307 R11: ffffed1012c74060 R12: ffffed1012c74022
R13: ffff8880963a0160 R14: ffff8880963a0110 R15: ffffffff81d5d3e0
io_uring_release+0x3e/0x50 fs/io_uring.c:7324
__fput+0x33e/0x880 fs/file_table.c:280
task_work_run+0xf4/0x1b0 kernel/task_work.c:123
exit_task_work include/linux/task_work.h:22 [inline]
do_exit+0xb53/0x2e10 kernel/exit.c:795
do_group_exit+0x125/0x340 kernel/exit.c:893
get_signal+0x47b/0x24e0 kernel/signal.c:2735
do_signal+0x81/0x2240 arch/x86/kernel/signal.c:784
exit_to_usermode_loop+0x26c/0x360 arch/x86/entry/common.c:161
prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline]
syscall_return_slowpath arch/x86/entry/common.c:279 [inline]
do_syscall_64+0x6b1/0x7d0 arch/x86/entry/common.c:305
entry_SYSCALL_64_after_hwframe+0x49/0xb3
RIP: 0033:0x45c829
Code: Bad RIP value.
RSP: 002b:00007fdd2a37fc78 EFLAGS: 00000246 ORIG_RAX: 00000000000001a9
RAX: 0000000000000003 RBX: 00000000004e0ce0 RCX: 000000000045c829
RDX: 0000000000000000 RSI: 0000000020000580 RDI: 00000000000000f1
RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000204 R14: 00000000004c425f R15: 00007fdd2a3806d4
On 5/11/20 8:17 PM, syzbot wrote:
> syzbot has found a reproducer for the following crash on:
>
> HEAD commit: ac935d22 Add linux-next specific files for 20200415
> git tree: linux-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=13a38f0a100000
> kernel config: https://syzkaller.appspot.com/x/.config?x=bc498783097e9019
> dashboard link: https://syzkaller.appspot.com/bug?extid=66243bb7126c410cefe6
> compiler: gcc (GCC) 9.0.0 20181231 (experimental)
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=179b3b32100000
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: [email protected]
>
> rcu: INFO: rcu_preempt self-detected stall on CPU
> rcu: 0-....: (10533 ticks this GP) idle=aea/1/0x4000000000000002 softirq=10553/10555 fqs=5249
> (t=10501 jiffies g=12777 q=556)
> NMI backtrace for cpu 0
> CPU: 0 PID: 8729 Comm: syz-executor.3 Not tainted 5.7.0-rc1-next-20200415-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+0x188/0x20d lib/dump_stack.c:118
> nmi_cpu_backtrace.cold+0x70/0xb1 lib/nmi_backtrace.c:101
> nmi_trigger_cpumask_backtrace+0x231/0x27e lib/nmi_backtrace.c:62
> trigger_single_cpu_backtrace include/linux/nmi.h:165 [inline]
> rcu_dump_cpu_stacks+0x19b/0x1e5 kernel/rcu/tree_stall.h:254
> print_cpu_stall kernel/rcu/tree_stall.h:475 [inline]
> check_cpu_stall kernel/rcu/tree_stall.h:549 [inline]
> rcu_pending kernel/rcu/tree.c:3225 [inline]
> rcu_sched_clock_irq.cold+0x55d/0xd00 kernel/rcu/tree.c:2296
> update_process_times+0x25/0x60 kernel/time/timer.c:1727
> tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:176
> tick_sched_timer+0x4e/0x140 kernel/time/tick-sched.c:1320
> __run_hrtimer kernel/time/hrtimer.c:1520 [inline]
> __hrtimer_run_queues+0x5ca/0xed0 kernel/time/hrtimer.c:1584
> hrtimer_interrupt+0x312/0x770 kernel/time/hrtimer.c:1646
> local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1113 [inline]
> smp_apic_timer_interrupt+0x15b/0x600 arch/x86/kernel/apic/apic.c:1138
> apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829
> </IRQ>
> RIP: 0010:io_ring_ctx_wait_and_kill+0x98/0x5a0 fs/io_uring.c:7301
> Code: 01 00 00 4d 89 f4 48 b8 00 00 00 00 00 fc ff df 4c 89 ed 49 c1 ec 03 48 c1 ed 03 49 01 c4 48 01 c5 eb 1c e8 ba 65 9d ff f3 90 <41> 80 3c 24 00 0f 85 53 04 00 00 48 83 bb 10 01 00 00 00 74 21 e8
> RSP: 0018:ffffc900054d7a50 EFLAGS: 00000293 ORIG_RAX: ffffffffffffff13
> RAX: ffff888097c14400 RBX: ffff8880963a0000 RCX: 1ffff92000a9af37
> RDX: 0000000000000000 RSI: ffffffff81d5ced6 RDI: ffff8880963a0300
> RBP: ffffed1012c7402c R08: 0000000000000001 R09: ffffed1012c74061
> R10: ffff8880963a0307 R11: ffffed1012c74060 R12: ffffed1012c74022
> R13: ffff8880963a0160 R14: ffff8880963a0110 R15: ffffffff81d5d3e0
> io_uring_release+0x3e/0x50 fs/io_uring.c:7324
> __fput+0x33e/0x880 fs/file_table.c:280
> task_work_run+0xf4/0x1b0 kernel/task_work.c:123
> exit_task_work include/linux/task_work.h:22 [inline]
> do_exit+0xb53/0x2e10 kernel/exit.c:795
> do_group_exit+0x125/0x340 kernel/exit.c:893
> get_signal+0x47b/0x24e0 kernel/signal.c:2735
> do_signal+0x81/0x2240 arch/x86/kernel/signal.c:784
> exit_to_usermode_loop+0x26c/0x360 arch/x86/entry/common.c:161
> prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline]
> syscall_return_slowpath arch/x86/entry/common.c:279 [inline]
> do_syscall_64+0x6b1/0x7d0 arch/x86/entry/common.c:305
> entry_SYSCALL_64_after_hwframe+0x49/0xb3
> RIP: 0033:0x45c829
> Code: Bad RIP value.
> RSP: 002b:00007fdd2a37fc78 EFLAGS: 00000246 ORIG_RAX: 00000000000001a9
> RAX: 0000000000000003 RBX: 00000000004e0ce0 RCX: 000000000045c829
> RDX: 0000000000000000 RSI: 0000000020000580 RDI: 00000000000000f1
> RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
> R13: 0000000000000204 R14: 00000000004c425f R15: 00007fdd2a3806d4
#syz fix: io_uring: use cond_resched() in io_ring_ctx_wait_and_kill()
--
Jens Axboe