Hello,
syzbot found the following issue on:
HEAD commit: 4442749a Add linux-next specific files for 20200902
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=12f9e915900000
kernel config: https://syzkaller.appspot.com/x/.config?x=39134fcec6c78e33
dashboard link: https://syzkaller.appspot.com/bug?extid=107dd59d1efcaf3ffca4
compiler: gcc (GCC) 10.1.0-syz 20200507
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11594671900000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=111ca835900000
The issue was bisected to:
commit dfe127799f8e663c7e3e48b5275ca538b278177b
Author: Stefano Garzarella <[email protected]>
Date: Thu Aug 27 14:58:31 2020 +0000
io_uring: allow disabling rings during the creation
bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=11bc66c1900000
final oops: https://syzkaller.appspot.com/x/report.txt?x=13bc66c1900000
console output: https://syzkaller.appspot.com/x/log.txt?x=15bc66c1900000
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: [email protected]
Fixes: dfe127799f8e ("io_uring: allow disabling rings during the creation")
INFO: task syz-executor047:6853 blocked for more than 143 seconds.
Not tainted 5.9.0-rc3-next-20200902-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor047 state:D stack:28104 pid: 6853 ppid: 6847 flags:0x00004000
Call Trace:
context_switch kernel/sched/core.c:3777 [inline]
__schedule+0xea9/0x2230 kernel/sched/core.c:4526
schedule+0xd0/0x2a0 kernel/sched/core.c:4601
schedule_timeout+0x1d8/0x250 kernel/time/timer.c:1855
do_wait_for_common kernel/sched/completion.c:85 [inline]
__wait_for_common kernel/sched/completion.c:106 [inline]
wait_for_common kernel/sched/completion.c:117 [inline]
wait_for_completion+0x163/0x260 kernel/sched/completion.c:138
io_sq_thread_stop fs/io_uring.c:6906 [inline]
io_finish_async fs/io_uring.c:6920 [inline]
io_sq_offload_create fs/io_uring.c:7595 [inline]
io_uring_create fs/io_uring.c:8671 [inline]
io_uring_setup+0x1495/0x29a0 fs/io_uring.c:8744
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x440299
Code: Bad RIP value.
RSP: 002b:00007ffc57cff668 EFLAGS: 00000246 ORIG_RAX: 00000000000001a9
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 0000000000440299
RDX: 0000000000400b40 RSI: 0000000020000100 RDI: 0000000000003ffe
RBP: 00000000006ca018 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000246 R12: 0000000000401aa0
R13: 0000000000401b30 R14: 0000000000000000 R15: 0000000000000000
INFO: task io_uring-sq:6854 blocked for more than 143 seconds.
Not tainted 5.9.0-rc3-next-20200902-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:io_uring-sq state:D stack:31200 pid: 6854 ppid: 2 flags:0x00004000
Call Trace:
context_switch kernel/sched/core.c:3777 [inline]
__schedule+0xea9/0x2230 kernel/sched/core.c:4526
schedule+0xd0/0x2a0 kernel/sched/core.c:4601
schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:4660
kthread+0x2ac/0x4a0 kernel/kthread.c:285
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
Showing all locks held in the system:
1 lock held by khungtaskd/1174:
#0: ffffffff89c67980 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:5829
3 locks held by in:imklog/6525:
#0: ffff8880a3de2df0 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe9/0x100 fs/file.c:930
#1: ffff8880907d8968 (&mm->mmap_lock#2){++++}-{3:3}, at: rq_lock kernel/sched/sched.h:1292 [inline]
#1: ffff8880907d8968 (&mm->mmap_lock#2){++++}-{3:3}, at: ttwu_queue kernel/sched/core.c:2698 [inline]
#1: ffff8880907d8968 (&mm->mmap_lock#2){++++}-{3:3}, at: try_to_wake_up+0x52b/0x12b0 kernel/sched/core.c:2978
#2: ffff8880ae620ec8 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_switch+0x2fb/0x400 kernel/sched/psi.c:833
=============================================
NMI backtrace for cpu 1
CPU: 1 PID: 1174 Comm: khungtaskd Not tainted 5.9.0-rc3-next-20200902-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x198/0x1fd lib/dump_stack.c:118
nmi_cpu_backtrace.cold+0x44/0xd7 lib/nmi_backtrace.c:105
nmi_trigger_cpumask_backtrace+0x1b3/0x223 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:147 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:253 [inline]
watchdog+0xd89/0xf30 kernel/hung_task.c:339
kthread+0x3b5/0x4a0 kernel/kthread.c:292
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 3901 Comm: systemd-journal Not tainted 5.9.0-rc3-next-20200902-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:unwind_next_frame+0x139a/0x1f90 arch/x86/kernel/unwind_orc.c:607
Code: 49 39 47 28 0f 85 3e f0 ff ff 80 3d df 2c 84 09 00 0f 85 31 f0 ff ff e9 06 18 00 00 48 b8 00 00 00 00 00 fc ff df 48 8b 14 24 <48> c1 ea 03 80 3c 02 00 0f 85 02 08 00 00 49 8d 7f 08 49 8b 6f 38
RSP: 0018:ffffc900040475f8 EFLAGS: 00000246
RAX: dffffc0000000000 RBX: 1ffff92000808ec7 RCX: 1ffff92000808ee2
RDX: ffffc90004047708 RSI: ffffc90004047aa8 RDI: ffffc90004047aa8
RBP: 0000000000000001 R08: ffffffff8b32a670 R09: 0000000000000001
R10: 000000000007201e R11: 0000000000000001 R12: ffffc90004047ac8
R13: ffffc90004047705 R14: ffffc90004047720 R15: ffffc900040476d0
FS: 00007efc659ac8c0(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007efc62d51000 CR3: 0000000093d6a000 CR4: 00000000001506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
arch_stack_walk+0x81/0xf0 arch/x86/kernel/stacktrace.c:25
stack_trace_save+0x8c/0xc0 kernel/stacktrace.c:123
kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48
kasan_set_track mm/kasan/common.c:56 [inline]
__kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:461
slab_post_alloc_hook mm/slab.h:517 [inline]
slab_alloc mm/slab.c:3312 [inline]
kmem_cache_alloc+0x13a/0x3a0 mm/slab.c:3482
kmem_cache_zalloc include/linux/slab.h:656 [inline]
__alloc_file+0x21/0x350 fs/file_table.c:101
alloc_empty_file+0x6d/0x170 fs/file_table.c:151
path_openat+0xe3/0x2730 fs/namei.c:3354
do_filp_open+0x17e/0x3c0 fs/namei.c:3395
do_sys_openat2+0x16d/0x420 fs/open.c:1168
do_sys_open fs/open.c:1184 [inline]
__do_sys_open fs/open.c:1192 [inline]
__se_sys_open fs/open.c:1188 [inline]
__x64_sys_open+0x119/0x1c0 fs/open.c:1188
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7efc64f3c840
Code: 73 01 c3 48 8b 0d 68 77 20 00 f7 d8 64 89 01 48 83 c8 ff c3 66 0f 1f 44 00 00 83 3d 89 bb 20 00 00 75 10 b8 02 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 31 c3 48 83 ec 08 e8 1e f6 ff ff 48 89 04 24
RSP: 002b:00007ffc45e60f18 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 00007ffc45e61220 RCX: 00007efc64f3c840
RDX: 00000000000001a0 RSI: 0000000000080042 RDI: 00005626d683e6d0
RBP: 000000000000000d R08: 000000000000c0ff R09: 00000000ffffffff
R10: 0000000000000069 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00005626d6831040 R14: 00007ffc45e611e0 R15: 00005626d683e720
---
This report 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 issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
For information about bisection process see: https://goo.gl/tpsmEJ#bisection
syzbot can test patches for this issue, for details see:
https://goo.gl/tpsmEJ#testing-patches
On 9/3/20 5:15 AM, Hillf Danton wrote:
>
> Thu, 03 Sep 2020 01:38:15 -0700
>> syzbot found the following issue on:
>>
>> HEAD commit: 4442749a Add linux-next specific files for 20200902
>> git tree: linux-next
>> console output: https://syzkaller.appspot.com/x/log.txt?x=12f9e915900000
>> kernel config: https://syzkaller.appspot.com/x/.config?x=39134fcec6c78e33
>> dashboard link: https://syzkaller.appspot.com/bug?extid=107dd59d1efcaf3ffca4
>> compiler: gcc (GCC) 10.1.0-syz 20200507
>> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11594671900000
>> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=111ca835900000
>>
>> The issue was bisected to:
>>
>> commit dfe127799f8e663c7e3e48b5275ca538b278177b
>> Author: Stefano Garzarella <[email protected]>
>> Date: Thu Aug 27 14:58:31 2020 +0000
>>
>> io_uring: allow disabling rings during the creation
>>
>> bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=11bc66c1900000
>> final oops: https://syzkaller.appspot.com/x/report.txt?x=13bc66c1900000
>> console output: https://syzkaller.appspot.com/x/log.txt?x=15bc66c1900000
>>
>> IMPORTANT: if you fix the issue, please add the following tag to the commit:
>> Reported-by: [email protected]
>> Fixes: dfe127799f8e ("io_uring: allow disabling rings during the creation")
>>
>> INFO: task syz-executor047:6853 blocked for more than 143 seconds.
>> Not tainted 5.9.0-rc3-next-20200902-syzkaller #0
>> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
>> task:syz-executor047 state:D stack:28104 pid: 6853 ppid: 6847 flags:0x00004000
>> Call Trace:
>> context_switch kernel/sched/core.c:3777 [inline]
>> __schedule+0xea9/0x2230 kernel/sched/core.c:4526
>> schedule+0xd0/0x2a0 kernel/sched/core.c:4601
>> schedule_timeout+0x1d8/0x250 kernel/time/timer.c:1855
>> do_wait_for_common kernel/sched/completion.c:85 [inline]
>> __wait_for_common kernel/sched/completion.c:106 [inline]
>> wait_for_common kernel/sched/completion.c:117 [inline]
>> wait_for_completion+0x163/0x260 kernel/sched/completion.c:138
>> io_sq_thread_stop fs/io_uring.c:6906 [inline]
>> io_finish_async fs/io_uring.c:6920 [inline]
>> io_sq_offload_create fs/io_uring.c:7595 [inline]
>> io_uring_create fs/io_uring.c:8671 [inline]
>> io_uring_setup+0x1495/0x29a0 fs/io_uring.c:8744
>> do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
>> entry_SYSCALL_64_after_hwframe+0x44/0xa9
>> RIP: 0033:0x440299
>> Code: Bad RIP value.
>> RSP: 002b:00007ffc57cff668 EFLAGS: 00000246 ORIG_RAX: 00000000000001a9
>> RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 0000000000440299
>> RDX: 0000000000400b40 RSI: 0000000020000100 RDI: 0000000000003ffe
>> RBP: 00000000006ca018 R08: 0000000000000000 R09: 0000000000000000
>> R10: 00000000ffffffff R11: 0000000000000246 R12: 0000000000401aa0
>> R13: 0000000000401b30 R14: 0000000000000000 R15: 0000000000000000
>> INFO: task io_uring-sq:6854 blocked for more than 143 seconds.
>> Not tainted 5.9.0-rc3-next-20200902-syzkaller #0
>> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
>> task:io_uring-sq state:D stack:31200 pid: 6854 ppid: 2 flags:0x00004000
>> Call Trace:
>> context_switch kernel/sched/core.c:3777 [inline]
>> __schedule+0xea9/0x2230 kernel/sched/core.c:4526
>> schedule+0xd0/0x2a0 kernel/sched/core.c:4601
>> schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:4660
>> kthread+0x2ac/0x4a0 kernel/kthread.c:285
>> ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
>>
>> Showing all locks held in the system:
>> 1 lock held by khungtaskd/1174:
>> #0: ffffffff89c67980 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:5829
>> 3 locks held by in:imklog/6525:
>> #0: ffff8880a3de2df0 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe9/0x100 fs/file.c:930
>> #1: ffff8880907d8968 (&mm->mmap_lock#2){++++}-{3:3}, at: rq_lock kernel/sched/sched.h:1292 [inline]
>> #1: ffff8880907d8968 (&mm->mmap_lock#2){++++}-{3:3}, at: ttwu_queue kernel/sched/core.c:2698 [inline]
>> #1: ffff8880907d8968 (&mm->mmap_lock#2){++++}-{3:3}, at: try_to_wake_up+0x52b/0x12b0 kernel/sched/core.c:2978
>> #2: ffff8880ae620ec8 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_switch+0x2fb/0x400 kernel/sched/psi.c:833
>>
>> =============================================
>>
>> NMI backtrace for cpu 1
>> CPU: 1 PID: 1174 Comm: khungtaskd Not tainted 5.9.0-rc3-next-20200902-syzkaller #0
>> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
>> Call Trace:
>> __dump_stack lib/dump_stack.c:77 [inline]
>> dump_stack+0x198/0x1fd lib/dump_stack.c:118
>> nmi_cpu_backtrace.cold+0x44/0xd7 lib/nmi_backtrace.c:105
>> nmi_trigger_cpumask_backtrace+0x1b3/0x223 lib/nmi_backtrace.c:62
>> trigger_all_cpu_backtrace include/linux/nmi.h:147 [inline]
>> check_hung_uninterruptible_tasks kernel/hung_task.c:253 [inline]
>> watchdog+0xd89/0xf30 kernel/hung_task.c:339
>> kthread+0x3b5/0x4a0 kernel/kthread.c:292
>> ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
>> Sending NMI from CPU 1 to CPUs 0:
>> NMI backtrace for cpu 0
>> CPU: 0 PID: 3901 Comm: systemd-journal Not tainted 5.9.0-rc3-next-20200902-syzkaller #0
>> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
>> RIP: 0010:unwind_next_frame+0x139a/0x1f90 arch/x86/kernel/unwind_orc.c:607
>> Code: 49 39 47 28 0f 85 3e f0 ff ff 80 3d df 2c 84 09 00 0f 85 31 f0 ff ff e9 06 18 00 00 48 b8 00 00 00 00 00 fc ff df 48 8b 14 24 <48> c1 ea 03 80 3c 02 00 0f 85 02 08 00 00 49 8d 7f 08 49 8b 6f 38
>> RSP: 0018:ffffc900040475f8 EFLAGS: 00000246
>> RAX: dffffc0000000000 RBX: 1ffff92000808ec7 RCX: 1ffff92000808ee2
>> RDX: ffffc90004047708 RSI: ffffc90004047aa8 RDI: ffffc90004047aa8
>> RBP: 0000000000000001 R08: ffffffff8b32a670 R09: 0000000000000001
>> R10: 000000000007201e R11: 0000000000000001 R12: ffffc90004047ac8
>> R13: ffffc90004047705 R14: ffffc90004047720 R15: ffffc900040476d0
>> FS: 00007efc659ac8c0(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000
>> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>> CR2: 00007efc62d51000 CR3: 0000000093d6a000 CR4: 00000000001506f0
>> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>> Call Trace:
>> arch_stack_walk+0x81/0xf0 arch/x86/kernel/stacktrace.c:25
>> stack_trace_save+0x8c/0xc0 kernel/stacktrace.c:123
>> kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48
>> kasan_set_track mm/kasan/common.c:56 [inline]
>> __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:461
>> slab_post_alloc_hook mm/slab.h:517 [inline]
>> slab_alloc mm/slab.c:3312 [inline]
>> kmem_cache_alloc+0x13a/0x3a0 mm/slab.c:3482
>> kmem_cache_zalloc include/linux/slab.h:656 [inline]
>> __alloc_file+0x21/0x350 fs/file_table.c:101
>> alloc_empty_file+0x6d/0x170 fs/file_table.c:151
>> path_openat+0xe3/0x2730 fs/namei.c:3354
>> do_filp_open+0x17e/0x3c0 fs/namei.c:3395
>> do_sys_openat2+0x16d/0x420 fs/open.c:1168
>> do_sys_open fs/open.c:1184 [inline]
>> __do_sys_open fs/open.c:1192 [inline]
>> __se_sys_open fs/open.c:1188 [inline]
>> __x64_sys_open+0x119/0x1c0 fs/open.c:1188
>> do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
>> entry_SYSCALL_64_after_hwframe+0x44/0xa9
>
> Add wakeup to make sure the wait for completion will be completed.
>
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -6903,6 +6903,7 @@ static int io_sqe_files_unregister(struc
> static void io_sq_thread_stop(struct io_ring_ctx *ctx)
> {
> if (ctx->sqo_thread) {
> + wake_up_process(ctx->sqo_thread);
> wait_for_completion(&ctx->sq_thread_comp);
> /*
> * The park is a bit of a work-around, without it we get
Yeah this looks reasonable, if the thread is attempted stopped if it
was created de-activated and never started.
Needs a comment to that effect. Care to add that and send it as a
properly formatted patch (with commit message, etc)?
--
Jens Axboe
On Thu, Sep 3, 2020 at 1:44 PM Jens Axboe <[email protected]> wrote:
>
> On 9/3/20 5:15 AM, Hillf Danton wrote:
> >
> > Thu, 03 Sep 2020 01:38:15 -0700
> >> syzbot found the following issue on:
> >>
> >> HEAD commit: 4442749a Add linux-next specific files for 20200902
> >> git tree: linux-next
> >> console output: https://syzkaller.appspot.com/x/log.txt?x=12f9e915900000
> >> kernel config: https://syzkaller.appspot.com/x/.config?x=39134fcec6c78e33
> >> dashboard link: https://syzkaller.appspot.com/bug?extid=107dd59d1efcaf3ffca4
> >> compiler: gcc (GCC) 10.1.0-syz 20200507
> >> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11594671900000
> >> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=111ca835900000
> >>
> >> The issue was bisected to:
> >>
> >> commit dfe127799f8e663c7e3e48b5275ca538b278177b
> >> Author: Stefano Garzarella <[email protected]>
> >> Date: Thu Aug 27 14:58:31 2020 +0000
> >>
> >> io_uring: allow disabling rings during the creation
> >>
> >> bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=11bc66c1900000
> >> final oops: https://syzkaller.appspot.com/x/report.txt?x=13bc66c1900000
> >> console output: https://syzkaller.appspot.com/x/log.txt?x=15bc66c1900000
> >>
> >> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> >> Reported-by: [email protected]
> >> Fixes: dfe127799f8e ("io_uring: allow disabling rings during the creation")
> >>
> >> INFO: task syz-executor047:6853 blocked for more than 143 seconds.
> >> Not tainted 5.9.0-rc3-next-20200902-syzkaller #0
> >> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> >> task:syz-executor047 state:D stack:28104 pid: 6853 ppid: 6847 flags:0x00004000
> >> Call Trace:
> >> context_switch kernel/sched/core.c:3777 [inline]
> >> __schedule+0xea9/0x2230 kernel/sched/core.c:4526
> >> schedule+0xd0/0x2a0 kernel/sched/core.c:4601
> >> schedule_timeout+0x1d8/0x250 kernel/time/timer.c:1855
> >> do_wait_for_common kernel/sched/completion.c:85 [inline]
> >> __wait_for_common kernel/sched/completion.c:106 [inline]
> >> wait_for_common kernel/sched/completion.c:117 [inline]
> >> wait_for_completion+0x163/0x260 kernel/sched/completion.c:138
> >> io_sq_thread_stop fs/io_uring.c:6906 [inline]
> >> io_finish_async fs/io_uring.c:6920 [inline]
> >> io_sq_offload_create fs/io_uring.c:7595 [inline]
> >> io_uring_create fs/io_uring.c:8671 [inline]
> >> io_uring_setup+0x1495/0x29a0 fs/io_uring.c:8744
> >> do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
> >> entry_SYSCALL_64_after_hwframe+0x44/0xa9
> >> RIP: 0033:0x440299
> >> Code: Bad RIP value.
> >> RSP: 002b:00007ffc57cff668 EFLAGS: 00000246 ORIG_RAX: 00000000000001a9
> >> RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 0000000000440299
> >> RDX: 0000000000400b40 RSI: 0000000020000100 RDI: 0000000000003ffe
> >> RBP: 00000000006ca018 R08: 0000000000000000 R09: 0000000000000000
> >> R10: 00000000ffffffff R11: 0000000000000246 R12: 0000000000401aa0
> >> R13: 0000000000401b30 R14: 0000000000000000 R15: 0000000000000000
> >> INFO: task io_uring-sq:6854 blocked for more than 143 seconds.
> >> Not tainted 5.9.0-rc3-next-20200902-syzkaller #0
> >> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> >> task:io_uring-sq state:D stack:31200 pid: 6854 ppid: 2 flags:0x00004000
> >> Call Trace:
> >> context_switch kernel/sched/core.c:3777 [inline]
> >> __schedule+0xea9/0x2230 kernel/sched/core.c:4526
> >> schedule+0xd0/0x2a0 kernel/sched/core.c:4601
> >> schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:4660
> >> kthread+0x2ac/0x4a0 kernel/kthread.c:285
> >> ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
> >>
> >> Showing all locks held in the system:
> >> 1 lock held by khungtaskd/1174:
> >> #0: ffffffff89c67980 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:5829
> >> 3 locks held by in:imklog/6525:
> >> #0: ffff8880a3de2df0 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe9/0x100 fs/file.c:930
> >> #1: ffff8880907d8968 (&mm->mmap_lock#2){++++}-{3:3}, at: rq_lock kernel/sched/sched.h:1292 [inline]
> >> #1: ffff8880907d8968 (&mm->mmap_lock#2){++++}-{3:3}, at: ttwu_queue kernel/sched/core.c:2698 [inline]
> >> #1: ffff8880907d8968 (&mm->mmap_lock#2){++++}-{3:3}, at: try_to_wake_up+0x52b/0x12b0 kernel/sched/core.c:2978
> >> #2: ffff8880ae620ec8 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_switch+0x2fb/0x400 kernel/sched/psi.c:833
> >>
> >> =============================================
> >>
> >> NMI backtrace for cpu 1
> >> CPU: 1 PID: 1174 Comm: khungtaskd Not tainted 5.9.0-rc3-next-20200902-syzkaller #0
> >> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> >> Call Trace:
> >> __dump_stack lib/dump_stack.c:77 [inline]
> >> dump_stack+0x198/0x1fd lib/dump_stack.c:118
> >> nmi_cpu_backtrace.cold+0x44/0xd7 lib/nmi_backtrace.c:105
> >> nmi_trigger_cpumask_backtrace+0x1b3/0x223 lib/nmi_backtrace.c:62
> >> trigger_all_cpu_backtrace include/linux/nmi.h:147 [inline]
> >> check_hung_uninterruptible_tasks kernel/hung_task.c:253 [inline]
> >> watchdog+0xd89/0xf30 kernel/hung_task.c:339
> >> kthread+0x3b5/0x4a0 kernel/kthread.c:292
> >> ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
> >> Sending NMI from CPU 1 to CPUs 0:
> >> NMI backtrace for cpu 0
> >> CPU: 0 PID: 3901 Comm: systemd-journal Not tainted 5.9.0-rc3-next-20200902-syzkaller #0
> >> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> >> RIP: 0010:unwind_next_frame+0x139a/0x1f90 arch/x86/kernel/unwind_orc.c:607
> >> Code: 49 39 47 28 0f 85 3e f0 ff ff 80 3d df 2c 84 09 00 0f 85 31 f0 ff ff e9 06 18 00 00 48 b8 00 00 00 00 00 fc ff df 48 8b 14 24 <48> c1 ea 03 80 3c 02 00 0f 85 02 08 00 00 49 8d 7f 08 49 8b 6f 38
> >> RSP: 0018:ffffc900040475f8 EFLAGS: 00000246
> >> RAX: dffffc0000000000 RBX: 1ffff92000808ec7 RCX: 1ffff92000808ee2
> >> RDX: ffffc90004047708 RSI: ffffc90004047aa8 RDI: ffffc90004047aa8
> >> RBP: 0000000000000001 R08: ffffffff8b32a670 R09: 0000000000000001
> >> R10: 000000000007201e R11: 0000000000000001 R12: ffffc90004047ac8
> >> R13: ffffc90004047705 R14: ffffc90004047720 R15: ffffc900040476d0
> >> FS: 00007efc659ac8c0(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000
> >> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> >> CR2: 00007efc62d51000 CR3: 0000000093d6a000 CR4: 00000000001506f0
> >> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> >> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> >> Call Trace:
> >> arch_stack_walk+0x81/0xf0 arch/x86/kernel/stacktrace.c:25
> >> stack_trace_save+0x8c/0xc0 kernel/stacktrace.c:123
> >> kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48
> >> kasan_set_track mm/kasan/common.c:56 [inline]
> >> __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:461
> >> slab_post_alloc_hook mm/slab.h:517 [inline]
> >> slab_alloc mm/slab.c:3312 [inline]
> >> kmem_cache_alloc+0x13a/0x3a0 mm/slab.c:3482
> >> kmem_cache_zalloc include/linux/slab.h:656 [inline]
> >> __alloc_file+0x21/0x350 fs/file_table.c:101
> >> alloc_empty_file+0x6d/0x170 fs/file_table.c:151
> >> path_openat+0xe3/0x2730 fs/namei.c:3354
> >> do_filp_open+0x17e/0x3c0 fs/namei.c:3395
> >> do_sys_openat2+0x16d/0x420 fs/open.c:1168
> >> do_sys_open fs/open.c:1184 [inline]
> >> __do_sys_open fs/open.c:1192 [inline]
> >> __se_sys_open fs/open.c:1188 [inline]
> >> __x64_sys_open+0x119/0x1c0 fs/open.c:1188
> >> do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
> >> entry_SYSCALL_64_after_hwframe+0x44/0xa9
> >
> > Add wakeup to make sure the wait for completion will be completed.
> >
> > --- a/fs/io_uring.c
> > +++ b/fs/io_uring.c
> > @@ -6903,6 +6903,7 @@ static int io_sqe_files_unregister(struc
> > static void io_sq_thread_stop(struct io_ring_ctx *ctx)
> > {
> > if (ctx->sqo_thread) {
> > + wake_up_process(ctx->sqo_thread);
> > wait_for_completion(&ctx->sq_thread_comp);
> > /*
> > * The park is a bit of a work-around, without it we get
>
> Yeah this looks reasonable, if the thread is attempted stopped if it
> was created de-activated and never started.
>
> Needs a comment to that effect. Care to add that and send it as a
> properly formatted patch (with commit message, etc)?
What happened with this fix?
The bug is marked as fixed with commit "io_uring: fix task hung in
io_uring_setup":
https://syzkaller.appspot.com/bug?id=a2b6779df9f5006318875364e0f18cc3af14fa60
but this commit cannot be found in any tree.
On 10/30/20 4:01 AM, Dmitry Vyukov wrote:
> On Thu, Sep 3, 2020 at 1:44 PM Jens Axboe <[email protected]> wrote:
>>
>> On 9/3/20 5:15 AM, Hillf Danton wrote:
>>>
>>> Thu, 03 Sep 2020 01:38:15 -0700
>>>> syzbot found the following issue on:
>>>>
>>>> HEAD commit: 4442749a Add linux-next specific files for 20200902
>>>> git tree: linux-next
>>>> console output: https://syzkaller.appspot.com/x/log.txt?x=12f9e915900000
>>>> kernel config: https://syzkaller.appspot.com/x/.config?x=39134fcec6c78e33
>>>> dashboard link: https://syzkaller.appspot.com/bug?extid=107dd59d1efcaf3ffca4
>>>> compiler: gcc (GCC) 10.1.0-syz 20200507
>>>> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11594671900000
>>>> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=111ca835900000
>>>>
>>>> The issue was bisected to:
>>>>
>>>> commit dfe127799f8e663c7e3e48b5275ca538b278177b
>>>> Author: Stefano Garzarella <[email protected]>
>>>> Date: Thu Aug 27 14:58:31 2020 +0000
>>>>
>>>> io_uring: allow disabling rings during the creation
>>>>
>>>> bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=11bc66c1900000
>>>> final oops: https://syzkaller.appspot.com/x/report.txt?x=13bc66c1900000
>>>> console output: https://syzkaller.appspot.com/x/log.txt?x=15bc66c1900000
>>>>
>>>> IMPORTANT: if you fix the issue, please add the following tag to the commit:
>>>> Reported-by: [email protected]
>>>> Fixes: dfe127799f8e ("io_uring: allow disabling rings during the creation")
>>>>
>>>> INFO: task syz-executor047:6853 blocked for more than 143 seconds.
>>>> Not tainted 5.9.0-rc3-next-20200902-syzkaller #0
>>>> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
>>>> task:syz-executor047 state:D stack:28104 pid: 6853 ppid: 6847 flags:0x00004000
>>>> Call Trace:
>>>> context_switch kernel/sched/core.c:3777 [inline]
>>>> __schedule+0xea9/0x2230 kernel/sched/core.c:4526
>>>> schedule+0xd0/0x2a0 kernel/sched/core.c:4601
>>>> schedule_timeout+0x1d8/0x250 kernel/time/timer.c:1855
>>>> do_wait_for_common kernel/sched/completion.c:85 [inline]
>>>> __wait_for_common kernel/sched/completion.c:106 [inline]
>>>> wait_for_common kernel/sched/completion.c:117 [inline]
>>>> wait_for_completion+0x163/0x260 kernel/sched/completion.c:138
>>>> io_sq_thread_stop fs/io_uring.c:6906 [inline]
>>>> io_finish_async fs/io_uring.c:6920 [inline]
>>>> io_sq_offload_create fs/io_uring.c:7595 [inline]
>>>> io_uring_create fs/io_uring.c:8671 [inline]
>>>> io_uring_setup+0x1495/0x29a0 fs/io_uring.c:8744
>>>> do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
>>>> entry_SYSCALL_64_after_hwframe+0x44/0xa9
>>>> RIP: 0033:0x440299
>>>> Code: Bad RIP value.
>>>> RSP: 002b:00007ffc57cff668 EFLAGS: 00000246 ORIG_RAX: 00000000000001a9
>>>> RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 0000000000440299
>>>> RDX: 0000000000400b40 RSI: 0000000020000100 RDI: 0000000000003ffe
>>>> RBP: 00000000006ca018 R08: 0000000000000000 R09: 0000000000000000
>>>> R10: 00000000ffffffff R11: 0000000000000246 R12: 0000000000401aa0
>>>> R13: 0000000000401b30 R14: 0000000000000000 R15: 0000000000000000
>>>> INFO: task io_uring-sq:6854 blocked for more than 143 seconds.
>>>> Not tainted 5.9.0-rc3-next-20200902-syzkaller #0
>>>> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
>>>> task:io_uring-sq state:D stack:31200 pid: 6854 ppid: 2 flags:0x00004000
>>>> Call Trace:
>>>> context_switch kernel/sched/core.c:3777 [inline]
>>>> __schedule+0xea9/0x2230 kernel/sched/core.c:4526
>>>> schedule+0xd0/0x2a0 kernel/sched/core.c:4601
>>>> schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:4660
>>>> kthread+0x2ac/0x4a0 kernel/kthread.c:285
>>>> ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
>>>>
>>>> Showing all locks held in the system:
>>>> 1 lock held by khungtaskd/1174:
>>>> #0: ffffffff89c67980 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:5829
>>>> 3 locks held by in:imklog/6525:
>>>> #0: ffff8880a3de2df0 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe9/0x100 fs/file.c:930
>>>> #1: ffff8880907d8968 (&mm->mmap_lock#2){++++}-{3:3}, at: rq_lock kernel/sched/sched.h:1292 [inline]
>>>> #1: ffff8880907d8968 (&mm->mmap_lock#2){++++}-{3:3}, at: ttwu_queue kernel/sched/core.c:2698 [inline]
>>>> #1: ffff8880907d8968 (&mm->mmap_lock#2){++++}-{3:3}, at: try_to_wake_up+0x52b/0x12b0 kernel/sched/core.c:2978
>>>> #2: ffff8880ae620ec8 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_switch+0x2fb/0x400 kernel/sched/psi.c:833
>>>>
>>>> =============================================
>>>>
>>>> NMI backtrace for cpu 1
>>>> CPU: 1 PID: 1174 Comm: khungtaskd Not tainted 5.9.0-rc3-next-20200902-syzkaller #0
>>>> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
>>>> Call Trace:
>>>> __dump_stack lib/dump_stack.c:77 [inline]
>>>> dump_stack+0x198/0x1fd lib/dump_stack.c:118
>>>> nmi_cpu_backtrace.cold+0x44/0xd7 lib/nmi_backtrace.c:105
>>>> nmi_trigger_cpumask_backtrace+0x1b3/0x223 lib/nmi_backtrace.c:62
>>>> trigger_all_cpu_backtrace include/linux/nmi.h:147 [inline]
>>>> check_hung_uninterruptible_tasks kernel/hung_task.c:253 [inline]
>>>> watchdog+0xd89/0xf30 kernel/hung_task.c:339
>>>> kthread+0x3b5/0x4a0 kernel/kthread.c:292
>>>> ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
>>>> Sending NMI from CPU 1 to CPUs 0:
>>>> NMI backtrace for cpu 0
>>>> CPU: 0 PID: 3901 Comm: systemd-journal Not tainted 5.9.0-rc3-next-20200902-syzkaller #0
>>>> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
>>>> RIP: 0010:unwind_next_frame+0x139a/0x1f90 arch/x86/kernel/unwind_orc.c:607
>>>> Code: 49 39 47 28 0f 85 3e f0 ff ff 80 3d df 2c 84 09 00 0f 85 31 f0 ff ff e9 06 18 00 00 48 b8 00 00 00 00 00 fc ff df 48 8b 14 24 <48> c1 ea 03 80 3c 02 00 0f 85 02 08 00 00 49 8d 7f 08 49 8b 6f 38
>>>> RSP: 0018:ffffc900040475f8 EFLAGS: 00000246
>>>> RAX: dffffc0000000000 RBX: 1ffff92000808ec7 RCX: 1ffff92000808ee2
>>>> RDX: ffffc90004047708 RSI: ffffc90004047aa8 RDI: ffffc90004047aa8
>>>> RBP: 0000000000000001 R08: ffffffff8b32a670 R09: 0000000000000001
>>>> R10: 000000000007201e R11: 0000000000000001 R12: ffffc90004047ac8
>>>> R13: ffffc90004047705 R14: ffffc90004047720 R15: ffffc900040476d0
>>>> FS: 00007efc659ac8c0(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000
>>>> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>>>> CR2: 00007efc62d51000 CR3: 0000000093d6a000 CR4: 00000000001506f0
>>>> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>>>> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>>>> Call Trace:
>>>> arch_stack_walk+0x81/0xf0 arch/x86/kernel/stacktrace.c:25
>>>> stack_trace_save+0x8c/0xc0 kernel/stacktrace.c:123
>>>> kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48
>>>> kasan_set_track mm/kasan/common.c:56 [inline]
>>>> __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:461
>>>> slab_post_alloc_hook mm/slab.h:517 [inline]
>>>> slab_alloc mm/slab.c:3312 [inline]
>>>> kmem_cache_alloc+0x13a/0x3a0 mm/slab.c:3482
>>>> kmem_cache_zalloc include/linux/slab.h:656 [inline]
>>>> __alloc_file+0x21/0x350 fs/file_table.c:101
>>>> alloc_empty_file+0x6d/0x170 fs/file_table.c:151
>>>> path_openat+0xe3/0x2730 fs/namei.c:3354
>>>> do_filp_open+0x17e/0x3c0 fs/namei.c:3395
>>>> do_sys_openat2+0x16d/0x420 fs/open.c:1168
>>>> do_sys_open fs/open.c:1184 [inline]
>>>> __do_sys_open fs/open.c:1192 [inline]
>>>> __se_sys_open fs/open.c:1188 [inline]
>>>> __x64_sys_open+0x119/0x1c0 fs/open.c:1188
>>>> do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
>>>> entry_SYSCALL_64_after_hwframe+0x44/0xa9
>>>
>>> Add wakeup to make sure the wait for completion will be completed.
>>>
>>> --- a/fs/io_uring.c
>>> +++ b/fs/io_uring.c
>>> @@ -6903,6 +6903,7 @@ static int io_sqe_files_unregister(struc
>>> static void io_sq_thread_stop(struct io_ring_ctx *ctx)
>>> {
>>> if (ctx->sqo_thread) {
>>> + wake_up_process(ctx->sqo_thread);
>>> wait_for_completion(&ctx->sq_thread_comp);
>>> /*
>>> * The park is a bit of a work-around, without it we get
>>
>> Yeah this looks reasonable, if the thread is attempted stopped if it
>> was created de-activated and never started.
>>
>> Needs a comment to that effect. Care to add that and send it as a
>> properly formatted patch (with commit message, etc)?
>
> What happened with this fix?
> The bug is marked as fixed with commit "io_uring: fix task hung in
> io_uring_setup":
> https://syzkaller.appspot.com/bug?id=a2b6779df9f5006318875364e0f18cc3af14fa60
> but this commit cannot be found in any tree.
I don't think Hillf ever sent in that patch, but it did get corrected as
part of:
commit 7e84e1c7566a1df470a9e1f49d3db2ce311261a4
Author: Stefano Garzarella <[email protected]>
Date: Thu Aug 27 16:58:31 2020 +0200
io_uring: allow disabling rings during the creation
which should have been done as a separate patch. I'll queue one up for
-stable.
--
Jens Axboe
On Fri, Oct 30, 2020 at 3:01 PM Jens Axboe <[email protected]> wrote:
>
> On 10/30/20 4:01 AM, Dmitry Vyukov wrote:
> > On Thu, Sep 3, 2020 at 1:44 PM Jens Axboe <[email protected]> wrote:
> >>
> >> On 9/3/20 5:15 AM, Hillf Danton wrote:
> >>>
> >>> Thu, 03 Sep 2020 01:38:15 -0700
> >>>> syzbot found the following issue on:
> >>>>
> >>>> HEAD commit: 4442749a Add linux-next specific files for 20200902
> >>>> git tree: linux-next
> >>>> console output: https://syzkaller.appspot.com/x/log.txt?x=12f9e915900000
> >>>> kernel config: https://syzkaller.appspot.com/x/.config?x=39134fcec6c78e33
> >>>> dashboard link: https://syzkaller.appspot.com/bug?extid=107dd59d1efcaf3ffca4
> >>>> compiler: gcc (GCC) 10.1.0-syz 20200507
> >>>> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11594671900000
> >>>> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=111ca835900000
> >>>>
> >>>> The issue was bisected to:
> >>>>
> >>>> commit dfe127799f8e663c7e3e48b5275ca538b278177b
> >>>> Author: Stefano Garzarella <[email protected]>
> >>>> Date: Thu Aug 27 14:58:31 2020 +0000
> >>>>
> >>>> io_uring: allow disabling rings during the creation
> >>>>
> >>>> bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=11bc66c1900000
> >>>> final oops: https://syzkaller.appspot.com/x/report.txt?x=13bc66c1900000
> >>>> console output: https://syzkaller.appspot.com/x/log.txt?x=15bc66c1900000
> >>>>
> >>>> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> >>>> Reported-by: [email protected]
> >>>> Fixes: dfe127799f8e ("io_uring: allow disabling rings during the creation")
> >>>>
> >>>> INFO: task syz-executor047:6853 blocked for more than 143 seconds.
> >>>> Not tainted 5.9.0-rc3-next-20200902-syzkaller #0
> >>>> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> >>>> task:syz-executor047 state:D stack:28104 pid: 6853 ppid: 6847 flags:0x00004000
> >>>> Call Trace:
> >>>> context_switch kernel/sched/core.c:3777 [inline]
> >>>> __schedule+0xea9/0x2230 kernel/sched/core.c:4526
> >>>> schedule+0xd0/0x2a0 kernel/sched/core.c:4601
> >>>> schedule_timeout+0x1d8/0x250 kernel/time/timer.c:1855
> >>>> do_wait_for_common kernel/sched/completion.c:85 [inline]
> >>>> __wait_for_common kernel/sched/completion.c:106 [inline]
> >>>> wait_for_common kernel/sched/completion.c:117 [inline]
> >>>> wait_for_completion+0x163/0x260 kernel/sched/completion.c:138
> >>>> io_sq_thread_stop fs/io_uring.c:6906 [inline]
> >>>> io_finish_async fs/io_uring.c:6920 [inline]
> >>>> io_sq_offload_create fs/io_uring.c:7595 [inline]
> >>>> io_uring_create fs/io_uring.c:8671 [inline]
> >>>> io_uring_setup+0x1495/0x29a0 fs/io_uring.c:8744
> >>>> do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
> >>>> entry_SYSCALL_64_after_hwframe+0x44/0xa9
> >>>> RIP: 0033:0x440299
> >>>> Code: Bad RIP value.
> >>>> RSP: 002b:00007ffc57cff668 EFLAGS: 00000246 ORIG_RAX: 00000000000001a9
> >>>> RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 0000000000440299
> >>>> RDX: 0000000000400b40 RSI: 0000000020000100 RDI: 0000000000003ffe
> >>>> RBP: 00000000006ca018 R08: 0000000000000000 R09: 0000000000000000
> >>>> R10: 00000000ffffffff R11: 0000000000000246 R12: 0000000000401aa0
> >>>> R13: 0000000000401b30 R14: 0000000000000000 R15: 0000000000000000
> >>>> INFO: task io_uring-sq:6854 blocked for more than 143 seconds.
> >>>> Not tainted 5.9.0-rc3-next-20200902-syzkaller #0
> >>>> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> >>>> task:io_uring-sq state:D stack:31200 pid: 6854 ppid: 2 flags:0x00004000
> >>>> Call Trace:
> >>>> context_switch kernel/sched/core.c:3777 [inline]
> >>>> __schedule+0xea9/0x2230 kernel/sched/core.c:4526
> >>>> schedule+0xd0/0x2a0 kernel/sched/core.c:4601
> >>>> schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:4660
> >>>> kthread+0x2ac/0x4a0 kernel/kthread.c:285
> >>>> ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
> >>>>
> >>>> Showing all locks held in the system:
> >>>> 1 lock held by khungtaskd/1174:
> >>>> #0: ffffffff89c67980 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:5829
> >>>> 3 locks held by in:imklog/6525:
> >>>> #0: ffff8880a3de2df0 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe9/0x100 fs/file.c:930
> >>>> #1: ffff8880907d8968 (&mm->mmap_lock#2){++++}-{3:3}, at: rq_lock kernel/sched/sched.h:1292 [inline]
> >>>> #1: ffff8880907d8968 (&mm->mmap_lock#2){++++}-{3:3}, at: ttwu_queue kernel/sched/core.c:2698 [inline]
> >>>> #1: ffff8880907d8968 (&mm->mmap_lock#2){++++}-{3:3}, at: try_to_wake_up+0x52b/0x12b0 kernel/sched/core.c:2978
> >>>> #2: ffff8880ae620ec8 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_switch+0x2fb/0x400 kernel/sched/psi.c:833
> >>>>
> >>>> =============================================
> >>>>
> >>>> NMI backtrace for cpu 1
> >>>> CPU: 1 PID: 1174 Comm: khungtaskd Not tainted 5.9.0-rc3-next-20200902-syzkaller #0
> >>>> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> >>>> Call Trace:
> >>>> __dump_stack lib/dump_stack.c:77 [inline]
> >>>> dump_stack+0x198/0x1fd lib/dump_stack.c:118
> >>>> nmi_cpu_backtrace.cold+0x44/0xd7 lib/nmi_backtrace.c:105
> >>>> nmi_trigger_cpumask_backtrace+0x1b3/0x223 lib/nmi_backtrace.c:62
> >>>> trigger_all_cpu_backtrace include/linux/nmi.h:147 [inline]
> >>>> check_hung_uninterruptible_tasks kernel/hung_task.c:253 [inline]
> >>>> watchdog+0xd89/0xf30 kernel/hung_task.c:339
> >>>> kthread+0x3b5/0x4a0 kernel/kthread.c:292
> >>>> ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
> >>>> Sending NMI from CPU 1 to CPUs 0:
> >>>> NMI backtrace for cpu 0
> >>>> CPU: 0 PID: 3901 Comm: systemd-journal Not tainted 5.9.0-rc3-next-20200902-syzkaller #0
> >>>> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> >>>> RIP: 0010:unwind_next_frame+0x139a/0x1f90 arch/x86/kernel/unwind_orc.c:607
> >>>> Code: 49 39 47 28 0f 85 3e f0 ff ff 80 3d df 2c 84 09 00 0f 85 31 f0 ff ff e9 06 18 00 00 48 b8 00 00 00 00 00 fc ff df 48 8b 14 24 <48> c1 ea 03 80 3c 02 00 0f 85 02 08 00 00 49 8d 7f 08 49 8b 6f 38
> >>>> RSP: 0018:ffffc900040475f8 EFLAGS: 00000246
> >>>> RAX: dffffc0000000000 RBX: 1ffff92000808ec7 RCX: 1ffff92000808ee2
> >>>> RDX: ffffc90004047708 RSI: ffffc90004047aa8 RDI: ffffc90004047aa8
> >>>> RBP: 0000000000000001 R08: ffffffff8b32a670 R09: 0000000000000001
> >>>> R10: 000000000007201e R11: 0000000000000001 R12: ffffc90004047ac8
> >>>> R13: ffffc90004047705 R14: ffffc90004047720 R15: ffffc900040476d0
> >>>> FS: 00007efc659ac8c0(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000
> >>>> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> >>>> CR2: 00007efc62d51000 CR3: 0000000093d6a000 CR4: 00000000001506f0
> >>>> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> >>>> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> >>>> Call Trace:
> >>>> arch_stack_walk+0x81/0xf0 arch/x86/kernel/stacktrace.c:25
> >>>> stack_trace_save+0x8c/0xc0 kernel/stacktrace.c:123
> >>>> kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48
> >>>> kasan_set_track mm/kasan/common.c:56 [inline]
> >>>> __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:461
> >>>> slab_post_alloc_hook mm/slab.h:517 [inline]
> >>>> slab_alloc mm/slab.c:3312 [inline]
> >>>> kmem_cache_alloc+0x13a/0x3a0 mm/slab.c:3482
> >>>> kmem_cache_zalloc include/linux/slab.h:656 [inline]
> >>>> __alloc_file+0x21/0x350 fs/file_table.c:101
> >>>> alloc_empty_file+0x6d/0x170 fs/file_table.c:151
> >>>> path_openat+0xe3/0x2730 fs/namei.c:3354
> >>>> do_filp_open+0x17e/0x3c0 fs/namei.c:3395
> >>>> do_sys_openat2+0x16d/0x420 fs/open.c:1168
> >>>> do_sys_open fs/open.c:1184 [inline]
> >>>> __do_sys_open fs/open.c:1192 [inline]
> >>>> __se_sys_open fs/open.c:1188 [inline]
> >>>> __x64_sys_open+0x119/0x1c0 fs/open.c:1188
> >>>> do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
> >>>> entry_SYSCALL_64_after_hwframe+0x44/0xa9
> >>>
> >>> Add wakeup to make sure the wait for completion will be completed.
> >>>
> >>> --- a/fs/io_uring.c
> >>> +++ b/fs/io_uring.c
> >>> @@ -6903,6 +6903,7 @@ static int io_sqe_files_unregister(struc
> >>> static void io_sq_thread_stop(struct io_ring_ctx *ctx)
> >>> {
> >>> if (ctx->sqo_thread) {
> >>> + wake_up_process(ctx->sqo_thread);
> >>> wait_for_completion(&ctx->sq_thread_comp);
> >>> /*
> >>> * The park is a bit of a work-around, without it we get
> >>
> >> Yeah this looks reasonable, if the thread is attempted stopped if it
> >> was created de-activated and never started.
> >>
> >> Needs a comment to that effect. Care to add that and send it as a
> >> properly formatted patch (with commit message, etc)?
> >
> > What happened with this fix?
> > The bug is marked as fixed with commit "io_uring: fix task hung in
> > io_uring_setup":
> > https://syzkaller.appspot.com/bug?id=a2b6779df9f5006318875364e0f18cc3af14fa60
> > but this commit cannot be found in any tree.
>
> I don't think Hillf ever sent in that patch, but it did get corrected as
> part of:
>
> commit 7e84e1c7566a1df470a9e1f49d3db2ce311261a4
> Author: Stefano Garzarella <[email protected]>
> Date: Thu Aug 27 16:58:31 2020 +0200
>
> io_uring: allow disabling rings during the creation
>
> which should have been done as a separate patch. I'll queue one up for
> -stable.
Thanks.
Let's tell syzbot that this is not an issue anymore:
#syz fix: io_uring: allow disabling rings during the creation