* possible deadlock in free_ioctx_users
@ 2018-09-09 18:41 syzbot
2018-09-09 19:11 ` Matthew Wilcox
2018-09-10 9:28 ` Miklos Szeredi
0 siblings, 2 replies; 6+ messages in thread
From: syzbot @ 2018-09-09 18:41 UTC (permalink / raw)
To: bcrl, linux-aio, linux-fsdevel, linux-kernel, syzkaller-bugs, viro
Hello,
syzbot found the following crash on:
HEAD commit: f8f65382c98a Merge tag 'for-linus' of git://git.kernel.org..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=113260ae400000
kernel config: https://syzkaller.appspot.com/x/.config?x=8f59875069d721b6
dashboard link: https://syzkaller.appspot.com/bug?extid=d86c4426a01f60feddc7
compiler: gcc (GCC) 8.0.1 20180413 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=120baa9e400000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13979cbe400000
IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+d86c4426a01f60feddc7@syzkaller.appspotmail.com
random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
========================================================
WARNING: possible irq lock inversion dependency detected
4.19.0-rc2+ #229 Not tainted
--------------------------------------------------------
swapper/0/0 just changed the state of lock:
00000000c02bddef (&(&ctx->ctx_lock)->rlock){..-.}, at: spin_lock_irq
include/linux/spinlock.h:354 [inline]
00000000c02bddef (&(&ctx->ctx_lock)->rlock){..-.}, at:
free_ioctx_users+0xbc/0x710 fs/aio.c:603
but this lock took another, SOFTIRQ-unsafe lock in the past:
(&fiq->waitq){+.+.}
and interrupts could create inverse lock ordering between them.
other info that might help us debug this:
Possible interrupt unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&fiq->waitq);
local_irq_disable();
lock(&(&ctx->ctx_lock)->rlock);
lock(&fiq->waitq);
<Interrupt>
lock(&(&ctx->ctx_lock)->rlock);
*** DEADLOCK ***
2 locks held by swapper/0/0:
#0: 0000000077c9a56b (rcu_callback){....}, at: __rcu_reclaim
kernel/rcu/rcu.h:226 [inline]
#0: 0000000077c9a56b (rcu_callback){....}, at: rcu_do_batch
kernel/rcu/tree.c:2576 [inline]
#0: 0000000077c9a56b (rcu_callback){....}, at: invoke_rcu_callbacks
kernel/rcu/tree.c:2880 [inline]
#0: 0000000077c9a56b (rcu_callback){....}, at: __rcu_process_callbacks
kernel/rcu/tree.c:2847 [inline]
#0: 0000000077c9a56b (rcu_callback){....}, at:
rcu_process_callbacks+0x1012/0x2670 kernel/rcu/tree.c:2864
#1: 0000000031dcf310 (rcu_read_lock_sched){....}, at:
percpu_ref_call_confirm_rcu lib/percpu-refcount.c:119 [inline]
#1: 0000000031dcf310 (rcu_read_lock_sched){....}, at:
percpu_ref_switch_to_atomic_rcu+0x2b7/0x820 lib/percpu-refcount.c:158
the shortest dependencies between 2nd lock and 1st lock:
-> (&fiq->waitq){+.+.} ops: 4 {
HARDIRQ-ON-W at:
lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3901
__raw_spin_lock include/linux/spinlock_api_smp.h:142
[inline]
_raw_spin_lock+0x2d/0x40 kernel/locking/spinlock.c:144
spin_lock include/linux/spinlock.h:329 [inline]
flush_bg_queue+0x389/0x650 fs/fuse/dev.c:364
fuse_request_send_background_locked+0x2f5/0x5a0
fs/fuse/dev.c:598
fuse_request_send_background+0x135/0x180
fs/fuse/dev.c:606
cuse_send_init fs/fuse/cuse.c:458 [inline]
cuse_channel_open+0x6b0/0x963 fs/fuse/cuse.c:518
misc_open+0x3ca/0x560 drivers/char/misc.c:141
chrdev_open+0x25a/0x710 fs/char_dev.c:417
do_dentry_open+0x499/0x1250 fs/open.c:771
vfs_open+0xa0/0xd0 fs/open.c:880
do_last fs/namei.c:3418 [inline]
path_openat+0x12bf/0x5160 fs/namei.c:3534
do_filp_open+0x255/0x380 fs/namei.c:3564
do_sys_open+0x568/0x700 fs/open.c:1063
__do_sys_openat fs/open.c:1090 [inline]
__se_sys_openat fs/open.c:1084 [inline]
__x64_sys_openat+0x9d/0x100 fs/open.c:1084
do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
SOFTIRQ-ON-W at:
lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3901
__raw_spin_lock include/linux/spinlock_api_smp.h:142
[inline]
_raw_spin_lock+0x2d/0x40 kernel/locking/spinlock.c:144
spin_lock include/linux/spinlock.h:329 [inline]
flush_bg_queue+0x389/0x650 fs/fuse/dev.c:364
fuse_request_send_background_locked+0x2f5/0x5a0
fs/fuse/dev.c:598
fuse_request_send_background+0x135/0x180
fs/fuse/dev.c:606
cuse_send_init fs/fuse/cuse.c:458 [inline]
cuse_channel_open+0x6b0/0x963 fs/fuse/cuse.c:518
misc_open+0x3ca/0x560 drivers/char/misc.c:141
chrdev_open+0x25a/0x710 fs/char_dev.c:417
do_dentry_open+0x499/0x1250 fs/open.c:771
vfs_open+0xa0/0xd0 fs/open.c:880
do_last fs/namei.c:3418 [inline]
path_openat+0x12bf/0x5160 fs/namei.c:3534
do_filp_open+0x255/0x380 fs/namei.c:3564
do_sys_open+0x568/0x700 fs/open.c:1063
__do_sys_openat fs/open.c:1090 [inline]
__se_sys_openat fs/open.c:1084 [inline]
__x64_sys_openat+0x9d/0x100 fs/open.c:1084
do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
INITIAL USE at:
lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3901
__raw_spin_lock include/linux/spinlock_api_smp.h:142
[inline]
_raw_spin_lock+0x2d/0x40 kernel/locking/spinlock.c:144
spin_lock include/linux/spinlock.h:329 [inline]
flush_bg_queue+0x389/0x650 fs/fuse/dev.c:364
fuse_request_send_background_locked+0x2f5/0x5a0
fs/fuse/dev.c:598
fuse_request_send_background+0x135/0x180
fs/fuse/dev.c:606
cuse_send_init fs/fuse/cuse.c:458 [inline]
cuse_channel_open+0x6b0/0x963 fs/fuse/cuse.c:518
misc_open+0x3ca/0x560 drivers/char/misc.c:141
chrdev_open+0x25a/0x710 fs/char_dev.c:417
do_dentry_open+0x499/0x1250 fs/open.c:771
vfs_open+0xa0/0xd0 fs/open.c:880
do_last fs/namei.c:3418 [inline]
path_openat+0x12bf/0x5160 fs/namei.c:3534
do_filp_open+0x255/0x380 fs/namei.c:3564
do_sys_open+0x568/0x700 fs/open.c:1063
__do_sys_openat fs/open.c:1090 [inline]
__se_sys_openat fs/open.c:1084 [inline]
__x64_sys_openat+0x9d/0x100 fs/open.c:1084
do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
}
... key at: [<ffffffff8b4763c0>] __key.42168+0x0/0x40
... acquired at:
__raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
_raw_spin_lock+0x2d/0x40 kernel/locking/spinlock.c:144
spin_lock include/linux/spinlock.h:329 [inline]
aio_poll+0x760/0x1420 fs/aio.c:1747
io_submit_one+0xab8/0x1090 fs/aio.c:1850
__do_sys_io_submit fs/aio.c:1916 [inline]
__se_sys_io_submit fs/aio.c:1887 [inline]
__x64_sys_io_submit+0x1b9/0x5d0 fs/aio.c:1887
do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
-> (&(&ctx->ctx_lock)->rlock){..-.} ops: 2 {
IN-SOFTIRQ-W at:
lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3901
__raw_spin_lock_irq
include/linux/spinlock_api_smp.h:128 [inline]
_raw_spin_lock_irq+0x61/0x80
kernel/locking/spinlock.c:160
spin_lock_irq include/linux/spinlock.h:354 [inline]
free_ioctx_users+0xbc/0x710 fs/aio.c:603
percpu_ref_put_many include/linux/percpu-refcount.h:284
[inline]
percpu_ref_put include/linux/percpu-refcount.h:300
[inline]
percpu_ref_call_confirm_rcu lib/percpu-refcount.c:123
[inline]
percpu_ref_switch_to_atomic_rcu+0x62c/0x820
lib/percpu-refcount.c:158
__rcu_reclaim kernel/rcu/rcu.h:236 [inline]
rcu_do_batch kernel/rcu/tree.c:2576 [inline]
invoke_rcu_callbacks kernel/rcu/tree.c:2880 [inline]
__rcu_process_callbacks kernel/rcu/tree.c:2847 [inline]
rcu_process_callbacks+0xf23/0x2670
kernel/rcu/tree.c:2864
__do_softirq+0x30b/0xad8 kernel/softirq.c:292
invoke_softirq kernel/softirq.c:372 [inline]
irq_exit+0x17f/0x1c0 kernel/softirq.c:412
exiting_irq arch/x86/include/asm/apic.h:536 [inline]
smp_apic_timer_interrupt+0x1cb/0x760
arch/x86/kernel/apic/apic.c:1056
apic_timer_interrupt+0xf/0x20
arch/x86/entry/entry_64.S:864
native_safe_halt+0x6/0x10
arch/x86/include/asm/irqflags.h:57
arch_safe_halt arch/x86/include/asm/paravirt.h:94
[inline]
default_idle+0xbf/0x490 arch/x86/kernel/process.c:498
arch_cpu_idle+0x10/0x20 arch/x86/kernel/process.c:489
default_idle_call+0x6d/0x90 kernel/sched/idle.c:93
cpuidle_idle_call kernel/sched/idle.c:153 [inline]
do_idle+0x3db/0x5b0 kernel/sched/idle.c:262
cpu_startup_entry+0x10c/0x120 kernel/sched/idle.c:368
rest_init+0xe2/0xe5 init/main.c:442
start_kernel+0x8f4/0x92f init/main.c:739
x86_64_start_reservations+0x29/0x2b
arch/x86/kernel/head64.c:452
x86_64_start_kernel+0x76/0x79
arch/x86/kernel/head64.c:433
secondary_startup_64+0xa4/0xb0
arch/x86/kernel/head_64.S:242
INITIAL USE at:
lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3901
__raw_spin_lock_irq include/linux/spinlock_api_smp.h:128
[inline]
_raw_spin_lock_irq+0x61/0x80
kernel/locking/spinlock.c:160
spin_lock_irq include/linux/spinlock.h:354 [inline]
aio_poll+0x738/0x1420 fs/aio.c:1746
io_submit_one+0xab8/0x1090 fs/aio.c:1850
__do_sys_io_submit fs/aio.c:1916 [inline]
__se_sys_io_submit fs/aio.c:1887 [inline]
__x64_sys_io_submit+0x1b9/0x5d0 fs/aio.c:1887
do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
}
... key at: [<ffffffff8b3dc960>] __key.50120+0x0/0x40
... acquired at:
mark_lock_irq kernel/locking/lockdep.c:2756 [inline]
mark_lock+0xa6b/0x1cb0 kernel/locking/lockdep.c:3128
mark_irqflags kernel/locking/lockdep.c:3006 [inline]
__lock_acquire+0x15f8/0x4ec0 kernel/locking/lockdep.c:3369
lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3901
__raw_spin_lock_irq include/linux/spinlock_api_smp.h:128 [inline]
_raw_spin_lock_irq+0x61/0x80 kernel/locking/spinlock.c:160
spin_lock_irq include/linux/spinlock.h:354 [inline]
free_ioctx_users+0xbc/0x710 fs/aio.c:603
percpu_ref_put_many include/linux/percpu-refcount.h:284 [inline]
percpu_ref_put include/linux/percpu-refcount.h:300 [inline]
percpu_ref_call_confirm_rcu lib/percpu-refcount.c:123 [inline]
percpu_ref_switch_to_atomic_rcu+0x62c/0x820 lib/percpu-refcount.c:158
__rcu_reclaim kernel/rcu/rcu.h:236 [inline]
rcu_do_batch kernel/rcu/tree.c:2576 [inline]
invoke_rcu_callbacks kernel/rcu/tree.c:2880 [inline]
__rcu_process_callbacks kernel/rcu/tree.c:2847 [inline]
rcu_process_callbacks+0xf23/0x2670 kernel/rcu/tree.c:2864
__do_softirq+0x30b/0xad8 kernel/softirq.c:292
invoke_softirq kernel/softirq.c:372 [inline]
irq_exit+0x17f/0x1c0 kernel/softirq.c:412
exiting_irq arch/x86/include/asm/apic.h:536 [inline]
smp_apic_timer_interrupt+0x1cb/0x760 arch/x86/kernel/apic/apic.c:1056
apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:864
native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:57
arch_safe_halt arch/x86/include/asm/paravirt.h:94 [inline]
default_idle+0xbf/0x490 arch/x86/kernel/process.c:498
arch_cpu_idle+0x10/0x20 arch/x86/kernel/process.c:489
default_idle_call+0x6d/0x90 kernel/sched/idle.c:93
cpuidle_idle_call kernel/sched/idle.c:153 [inline]
do_idle+0x3db/0x5b0 kernel/sched/idle.c:262
cpu_startup_entry+0x10c/0x120 kernel/sched/idle.c:368
rest_init+0xe2/0xe5 init/main.c:442
start_kernel+0x8f4/0x92f init/main.c:739
x86_64_start_reservations+0x29/0x2b arch/x86/kernel/head64.c:452
x86_64_start_kernel+0x76/0x79 arch/x86/kernel/head64.c:433
secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:242
stack backtrace:
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.19.0-rc2+ #229
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+0x1c4/0x2b4 lib/dump_stack.c:113
print_irq_inversion_bug.part.35+0x2c7/0x2d6 kernel/locking/lockdep.c:2622
print_irq_inversion_bug kernel/locking/lockdep.c:2625 [inline]
check_usage_forwards.cold.57+0x20/0x29 kernel/locking/lockdep.c:2647
mark_lock_irq kernel/locking/lockdep.c:2756 [inline]
mark_lock+0xa6b/0x1cb0 kernel/locking/lockdep.c:3128
mark_irqflags kernel/locking/lockdep.c:3006 [inline]
__lock_acquire+0x15f8/0x4ec0 kernel/locking/lockdep.c:3369
lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3901
__raw_spin_lock_irq include/linux/spinlock_api_smp.h:128 [inline]
_raw_spin_lock_irq+0x61/0x80 kernel/locking/spinlock.c:160
spin_lock_irq include/linux/spinlock.h:354 [inline]
free_ioctx_users+0xbc/0x710 fs/aio.c:603
percpu_ref_put_many include/linux/percpu-refcount.h:284 [inline]
percpu_ref_put include/linux/percpu-refcount.h:300 [inline]
percpu_ref_call_confirm_rcu lib/percpu-refcount.c:123 [inline]
percpu_ref_switch_to_atomic_rcu+0x62c/0x820 lib/percpu-refcount.c:158
__rcu_reclaim kernel/rcu/rcu.h:236 [inline]
rcu_do_batch kernel/rcu/tree.c:2576 [inline]
invoke_rcu_callbacks kernel/rcu/tree.c:2880 [inline]
__rcu_process_callbacks kernel/rcu/tree.c:2847 [inline]
rcu_process_callbacks+0xf23/0x2670 kernel/rcu/tree.c:2864
__do_softirq+0x30b/0xad8 kernel/softirq.c:292
invoke_softirq kernel/softirq.c:372 [inline]
irq_exit+0x17f/0x1c0 kernel/softirq.c:412
exiting_irq arch/x86/include/asm/apic.h:536 [inline]
smp_apic_timer_interrupt+0x1cb/0x760 arch/x86/kernel/apic/apic.c:1056
apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:864
</IRQ>
RIP: 0010:native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:57
Code: e9 2c ff ff ff 48 89 c7 48 89 45 d8 e8 43 b9 02 fa 48 8b 45 d8 e9 ca
fe ff ff 48 89 df e8 32 b9 02 fa eb 82 55 48 89 e5 fb f4 <5d> c3 0f 1f 84
00 00 00 00 00 55 48 89 e5 f4 5d c3 90 90 90 90 90
RSP: 0018:ffffffff89407bb8 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff13
RAX: dffffc0000000000 RBX: 1ffffffff1280f7b RCX: 0000000000000000
RDX: 1ffffffff12a4538 RSI: 0000000000000001 RDI: ffffffff895229c0
RBP: ffffffff89407bb8 R08: ffffffff89475fc0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff89407c78
R13: ffffffff8a3149a0 R14: 0000000000000000 R15: 0000000000000000
arch_safe_halt arch/x86/include/asm/paravirt.h:94 [inline]
default_idle+0xbf/0x490 arch/x86/kernel/process.c:498
arch_cpu_idle+0x10/0x20 arch/x86/kernel/process.c:489
default_idle_call+0x6d/0x90 kernel/sched/idle.c:93
cpuidle_idle_call kernel/sched/idle.c:153 [inline]
do_idle+0x3db/0x5b0 kernel/sched/idle.c:262
cpu_startup_entry+0x10c/0x120 kernel/sched/idle.c:368
rest_init+0xe2/0xe5 init/main.c:442
start_kernel+0x8f4/0x92f init/main.c:739
? early_idt_handler_common+
---
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 syzkaller@googlegroups.com.
syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#bug-status-tracking for how to communicate with
syzbot.
syzbot can test patches for this bug, for details see:
https://goo.gl/tpsmEJ#testing-patches
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: possible deadlock in free_ioctx_users
2018-09-09 18:41 possible deadlock in free_ioctx_users syzbot
@ 2018-09-09 19:11 ` Matthew Wilcox
2018-09-10 9:28 ` Miklos Szeredi
1 sibling, 0 replies; 6+ messages in thread
From: Matthew Wilcox @ 2018-09-09 19:11 UTC (permalink / raw)
To: syzbot
Cc: Andrey Ryabinin, Miklos Szeredi, Kirill Tkhai, bcrl, linux-aio,
linux-fsdevel, linux-kernel, syzkaller-bugs, viro
I would be inclined to blame FUSE for this problem.
On Sun, Sep 09, 2018 at 11:41:02AM -0700, syzbot wrote:
> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit: f8f65382c98a Merge tag 'for-linus' of git://git.kernel.org..
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=113260ae400000
> kernel config: https://syzkaller.appspot.com/x/.config?x=8f59875069d721b6
> dashboard link: https://syzkaller.appspot.com/bug?extid=d86c4426a01f60feddc7
> compiler: gcc (GCC) 8.0.1 20180413 (experimental)
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=120baa9e400000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13979cbe400000
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+d86c4426a01f60feddc7@syzkaller.appspotmail.com
>
> random: sshd: uninitialized urandom read (32 bytes read)
> random: sshd: uninitialized urandom read (32 bytes read)
> random: sshd: uninitialized urandom read (32 bytes read)
>
> ========================================================
> WARNING: possible irq lock inversion dependency detected
> 4.19.0-rc2+ #229 Not tainted
> --------------------------------------------------------
> swapper/0/0 just changed the state of lock:
> 00000000c02bddef (&(&ctx->ctx_lock)->rlock){..-.}, at: spin_lock_irq
> include/linux/spinlock.h:354 [inline]
> 00000000c02bddef (&(&ctx->ctx_lock)->rlock){..-.}, at:
> free_ioctx_users+0xbc/0x710 fs/aio.c:603
> but this lock took another, SOFTIRQ-unsafe lock in the past:
> (&fiq->waitq){+.+.}
>
>
> and interrupts could create inverse lock ordering between them.
>
>
> other info that might help us debug this:
> Possible interrupt unsafe locking scenario:
>
> CPU0 CPU1
> ---- ----
> lock(&fiq->waitq);
> local_irq_disable();
> lock(&(&ctx->ctx_lock)->rlock);
> lock(&fiq->waitq);
> <Interrupt>
> lock(&(&ctx->ctx_lock)->rlock);
>
> *** DEADLOCK ***
>
> 2 locks held by swapper/0/0:
> #0: 0000000077c9a56b (rcu_callback){....}, at: __rcu_reclaim
> kernel/rcu/rcu.h:226 [inline]
> #0: 0000000077c9a56b (rcu_callback){....}, at: rcu_do_batch
> kernel/rcu/tree.c:2576 [inline]
> #0: 0000000077c9a56b (rcu_callback){....}, at: invoke_rcu_callbacks
> kernel/rcu/tree.c:2880 [inline]
> #0: 0000000077c9a56b (rcu_callback){....}, at: __rcu_process_callbacks
> kernel/rcu/tree.c:2847 [inline]
> #0: 0000000077c9a56b (rcu_callback){....}, at:
> rcu_process_callbacks+0x1012/0x2670 kernel/rcu/tree.c:2864
> #1: 0000000031dcf310 (rcu_read_lock_sched){....}, at:
> percpu_ref_call_confirm_rcu lib/percpu-refcount.c:119 [inline]
> #1: 0000000031dcf310 (rcu_read_lock_sched){....}, at:
> percpu_ref_switch_to_atomic_rcu+0x2b7/0x820 lib/percpu-refcount.c:158
>
> the shortest dependencies between 2nd lock and 1st lock:
> -> (&fiq->waitq){+.+.} ops: 4 {
> HARDIRQ-ON-W at:
> lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3901
> __raw_spin_lock include/linux/spinlock_api_smp.h:142
> [inline]
> _raw_spin_lock+0x2d/0x40 kernel/locking/spinlock.c:144
> spin_lock include/linux/spinlock.h:329 [inline]
> flush_bg_queue+0x389/0x650 fs/fuse/dev.c:364
> fuse_request_send_background_locked+0x2f5/0x5a0
> fs/fuse/dev.c:598
> fuse_request_send_background+0x135/0x180
> fs/fuse/dev.c:606
> cuse_send_init fs/fuse/cuse.c:458 [inline]
> cuse_channel_open+0x6b0/0x963 fs/fuse/cuse.c:518
> misc_open+0x3ca/0x560 drivers/char/misc.c:141
> chrdev_open+0x25a/0x710 fs/char_dev.c:417
> do_dentry_open+0x499/0x1250 fs/open.c:771
> vfs_open+0xa0/0xd0 fs/open.c:880
> do_last fs/namei.c:3418 [inline]
> path_openat+0x12bf/0x5160 fs/namei.c:3534
> do_filp_open+0x255/0x380 fs/namei.c:3564
> do_sys_open+0x568/0x700 fs/open.c:1063
> __do_sys_openat fs/open.c:1090 [inline]
> __se_sys_openat fs/open.c:1084 [inline]
> __x64_sys_openat+0x9d/0x100 fs/open.c:1084
> do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
> entry_SYSCALL_64_after_hwframe+0x49/0xbe
> SOFTIRQ-ON-W at:
> lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3901
> __raw_spin_lock include/linux/spinlock_api_smp.h:142
> [inline]
> _raw_spin_lock+0x2d/0x40 kernel/locking/spinlock.c:144
> spin_lock include/linux/spinlock.h:329 [inline]
> flush_bg_queue+0x389/0x650 fs/fuse/dev.c:364
> fuse_request_send_background_locked+0x2f5/0x5a0
> fs/fuse/dev.c:598
> fuse_request_send_background+0x135/0x180
> fs/fuse/dev.c:606
> cuse_send_init fs/fuse/cuse.c:458 [inline]
> cuse_channel_open+0x6b0/0x963 fs/fuse/cuse.c:518
> misc_open+0x3ca/0x560 drivers/char/misc.c:141
> chrdev_open+0x25a/0x710 fs/char_dev.c:417
> do_dentry_open+0x499/0x1250 fs/open.c:771
> vfs_open+0xa0/0xd0 fs/open.c:880
> do_last fs/namei.c:3418 [inline]
> path_openat+0x12bf/0x5160 fs/namei.c:3534
> do_filp_open+0x255/0x380 fs/namei.c:3564
> do_sys_open+0x568/0x700 fs/open.c:1063
> __do_sys_openat fs/open.c:1090 [inline]
> __se_sys_openat fs/open.c:1084 [inline]
> __x64_sys_openat+0x9d/0x100 fs/open.c:1084
> do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
> entry_SYSCALL_64_after_hwframe+0x49/0xbe
> INITIAL USE at:
> lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3901
> __raw_spin_lock include/linux/spinlock_api_smp.h:142
> [inline]
> _raw_spin_lock+0x2d/0x40 kernel/locking/spinlock.c:144
> spin_lock include/linux/spinlock.h:329 [inline]
> flush_bg_queue+0x389/0x650 fs/fuse/dev.c:364
> fuse_request_send_background_locked+0x2f5/0x5a0
> fs/fuse/dev.c:598
> fuse_request_send_background+0x135/0x180
> fs/fuse/dev.c:606
> cuse_send_init fs/fuse/cuse.c:458 [inline]
> cuse_channel_open+0x6b0/0x963 fs/fuse/cuse.c:518
> misc_open+0x3ca/0x560 drivers/char/misc.c:141
> chrdev_open+0x25a/0x710 fs/char_dev.c:417
> do_dentry_open+0x499/0x1250 fs/open.c:771
> vfs_open+0xa0/0xd0 fs/open.c:880
> do_last fs/namei.c:3418 [inline]
> path_openat+0x12bf/0x5160 fs/namei.c:3534
> do_filp_open+0x255/0x380 fs/namei.c:3564
> do_sys_open+0x568/0x700 fs/open.c:1063
> __do_sys_openat fs/open.c:1090 [inline]
> __se_sys_openat fs/open.c:1084 [inline]
> __x64_sys_openat+0x9d/0x100 fs/open.c:1084
> do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
> entry_SYSCALL_64_after_hwframe+0x49/0xbe
> }
> ... key at: [<ffffffff8b4763c0>] __key.42168+0x0/0x40
> ... acquired at:
> __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
> _raw_spin_lock+0x2d/0x40 kernel/locking/spinlock.c:144
> spin_lock include/linux/spinlock.h:329 [inline]
> aio_poll+0x760/0x1420 fs/aio.c:1747
> io_submit_one+0xab8/0x1090 fs/aio.c:1850
> __do_sys_io_submit fs/aio.c:1916 [inline]
> __se_sys_io_submit fs/aio.c:1887 [inline]
> __x64_sys_io_submit+0x1b9/0x5d0 fs/aio.c:1887
> do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
> entry_SYSCALL_64_after_hwframe+0x49/0xbe
>
> -> (&(&ctx->ctx_lock)->rlock){..-.} ops: 2 {
> IN-SOFTIRQ-W at:
> lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3901
> __raw_spin_lock_irq include/linux/spinlock_api_smp.h:128
> [inline]
> _raw_spin_lock_irq+0x61/0x80
> kernel/locking/spinlock.c:160
> spin_lock_irq include/linux/spinlock.h:354 [inline]
> free_ioctx_users+0xbc/0x710 fs/aio.c:603
> percpu_ref_put_many include/linux/percpu-refcount.h:284
> [inline]
> percpu_ref_put include/linux/percpu-refcount.h:300
> [inline]
> percpu_ref_call_confirm_rcu lib/percpu-refcount.c:123
> [inline]
> percpu_ref_switch_to_atomic_rcu+0x62c/0x820
> lib/percpu-refcount.c:158
> __rcu_reclaim kernel/rcu/rcu.h:236 [inline]
> rcu_do_batch kernel/rcu/tree.c:2576 [inline]
> invoke_rcu_callbacks kernel/rcu/tree.c:2880 [inline]
> __rcu_process_callbacks kernel/rcu/tree.c:2847 [inline]
> rcu_process_callbacks+0xf23/0x2670
> kernel/rcu/tree.c:2864
> __do_softirq+0x30b/0xad8 kernel/softirq.c:292
> invoke_softirq kernel/softirq.c:372 [inline]
> irq_exit+0x17f/0x1c0 kernel/softirq.c:412
> exiting_irq arch/x86/include/asm/apic.h:536 [inline]
> smp_apic_timer_interrupt+0x1cb/0x760
> arch/x86/kernel/apic/apic.c:1056
> apic_timer_interrupt+0xf/0x20
> arch/x86/entry/entry_64.S:864
> native_safe_halt+0x6/0x10
> arch/x86/include/asm/irqflags.h:57
> arch_safe_halt arch/x86/include/asm/paravirt.h:94
> [inline]
> default_idle+0xbf/0x490 arch/x86/kernel/process.c:498
> arch_cpu_idle+0x10/0x20 arch/x86/kernel/process.c:489
> default_idle_call+0x6d/0x90 kernel/sched/idle.c:93
> cpuidle_idle_call kernel/sched/idle.c:153 [inline]
> do_idle+0x3db/0x5b0 kernel/sched/idle.c:262
> cpu_startup_entry+0x10c/0x120 kernel/sched/idle.c:368
> rest_init+0xe2/0xe5 init/main.c:442
> start_kernel+0x8f4/0x92f init/main.c:739
> x86_64_start_reservations+0x29/0x2b
> arch/x86/kernel/head64.c:452
> x86_64_start_kernel+0x76/0x79
> arch/x86/kernel/head64.c:433
> secondary_startup_64+0xa4/0xb0
> arch/x86/kernel/head_64.S:242
> INITIAL USE at:
> lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3901
> __raw_spin_lock_irq include/linux/spinlock_api_smp.h:128
> [inline]
> _raw_spin_lock_irq+0x61/0x80
> kernel/locking/spinlock.c:160
> spin_lock_irq include/linux/spinlock.h:354 [inline]
> aio_poll+0x738/0x1420 fs/aio.c:1746
> io_submit_one+0xab8/0x1090 fs/aio.c:1850
> __do_sys_io_submit fs/aio.c:1916 [inline]
> __se_sys_io_submit fs/aio.c:1887 [inline]
> __x64_sys_io_submit+0x1b9/0x5d0 fs/aio.c:1887
> do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
> entry_SYSCALL_64_after_hwframe+0x49/0xbe
> }
> ... key at: [<ffffffff8b3dc960>] __key.50120+0x0/0x40
> ... acquired at:
> mark_lock_irq kernel/locking/lockdep.c:2756 [inline]
> mark_lock+0xa6b/0x1cb0 kernel/locking/lockdep.c:3128
> mark_irqflags kernel/locking/lockdep.c:3006 [inline]
> __lock_acquire+0x15f8/0x4ec0 kernel/locking/lockdep.c:3369
> lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3901
> __raw_spin_lock_irq include/linux/spinlock_api_smp.h:128 [inline]
> _raw_spin_lock_irq+0x61/0x80 kernel/locking/spinlock.c:160
> spin_lock_irq include/linux/spinlock.h:354 [inline]
> free_ioctx_users+0xbc/0x710 fs/aio.c:603
> percpu_ref_put_many include/linux/percpu-refcount.h:284 [inline]
> percpu_ref_put include/linux/percpu-refcount.h:300 [inline]
> percpu_ref_call_confirm_rcu lib/percpu-refcount.c:123 [inline]
> percpu_ref_switch_to_atomic_rcu+0x62c/0x820 lib/percpu-refcount.c:158
> __rcu_reclaim kernel/rcu/rcu.h:236 [inline]
> rcu_do_batch kernel/rcu/tree.c:2576 [inline]
> invoke_rcu_callbacks kernel/rcu/tree.c:2880 [inline]
> __rcu_process_callbacks kernel/rcu/tree.c:2847 [inline]
> rcu_process_callbacks+0xf23/0x2670 kernel/rcu/tree.c:2864
> __do_softirq+0x30b/0xad8 kernel/softirq.c:292
> invoke_softirq kernel/softirq.c:372 [inline]
> irq_exit+0x17f/0x1c0 kernel/softirq.c:412
> exiting_irq arch/x86/include/asm/apic.h:536 [inline]
> smp_apic_timer_interrupt+0x1cb/0x760 arch/x86/kernel/apic/apic.c:1056
> apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:864
> native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:57
> arch_safe_halt arch/x86/include/asm/paravirt.h:94 [inline]
> default_idle+0xbf/0x490 arch/x86/kernel/process.c:498
> arch_cpu_idle+0x10/0x20 arch/x86/kernel/process.c:489
> default_idle_call+0x6d/0x90 kernel/sched/idle.c:93
> cpuidle_idle_call kernel/sched/idle.c:153 [inline]
> do_idle+0x3db/0x5b0 kernel/sched/idle.c:262
> cpu_startup_entry+0x10c/0x120 kernel/sched/idle.c:368
> rest_init+0xe2/0xe5 init/main.c:442
> start_kernel+0x8f4/0x92f init/main.c:739
> x86_64_start_reservations+0x29/0x2b arch/x86/kernel/head64.c:452
> x86_64_start_kernel+0x76/0x79 arch/x86/kernel/head64.c:433
> secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:242
>
>
> stack backtrace:
> CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.19.0-rc2+ #229
> 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+0x1c4/0x2b4 lib/dump_stack.c:113
> print_irq_inversion_bug.part.35+0x2c7/0x2d6 kernel/locking/lockdep.c:2622
> print_irq_inversion_bug kernel/locking/lockdep.c:2625 [inline]
> check_usage_forwards.cold.57+0x20/0x29 kernel/locking/lockdep.c:2647
> mark_lock_irq kernel/locking/lockdep.c:2756 [inline]
> mark_lock+0xa6b/0x1cb0 kernel/locking/lockdep.c:3128
> mark_irqflags kernel/locking/lockdep.c:3006 [inline]
> __lock_acquire+0x15f8/0x4ec0 kernel/locking/lockdep.c:3369
> lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3901
> __raw_spin_lock_irq include/linux/spinlock_api_smp.h:128 [inline]
> _raw_spin_lock_irq+0x61/0x80 kernel/locking/spinlock.c:160
> spin_lock_irq include/linux/spinlock.h:354 [inline]
> free_ioctx_users+0xbc/0x710 fs/aio.c:603
> percpu_ref_put_many include/linux/percpu-refcount.h:284 [inline]
> percpu_ref_put include/linux/percpu-refcount.h:300 [inline]
> percpu_ref_call_confirm_rcu lib/percpu-refcount.c:123 [inline]
> percpu_ref_switch_to_atomic_rcu+0x62c/0x820 lib/percpu-refcount.c:158
> __rcu_reclaim kernel/rcu/rcu.h:236 [inline]
> rcu_do_batch kernel/rcu/tree.c:2576 [inline]
> invoke_rcu_callbacks kernel/rcu/tree.c:2880 [inline]
> __rcu_process_callbacks kernel/rcu/tree.c:2847 [inline]
> rcu_process_callbacks+0xf23/0x2670 kernel/rcu/tree.c:2864
> __do_softirq+0x30b/0xad8 kernel/softirq.c:292
> invoke_softirq kernel/softirq.c:372 [inline]
> irq_exit+0x17f/0x1c0 kernel/softirq.c:412
> exiting_irq arch/x86/include/asm/apic.h:536 [inline]
> smp_apic_timer_interrupt+0x1cb/0x760 arch/x86/kernel/apic/apic.c:1056
> apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:864
> </IRQ>
> RIP: 0010:native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:57
> Code: e9 2c ff ff ff 48 89 c7 48 89 45 d8 e8 43 b9 02 fa 48 8b 45 d8 e9 ca
> fe ff ff 48 89 df e8 32 b9 02 fa eb 82 55 48 89 e5 fb f4 <5d> c3 0f 1f 84 00
> 00 00 00 00 55 48 89 e5 f4 5d c3 90 90 90 90 90
> RSP: 0018:ffffffff89407bb8 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff13
> RAX: dffffc0000000000 RBX: 1ffffffff1280f7b RCX: 0000000000000000
> RDX: 1ffffffff12a4538 RSI: 0000000000000001 RDI: ffffffff895229c0
> RBP: ffffffff89407bb8 R08: ffffffff89475fc0 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff89407c78
> R13: ffffffff8a3149a0 R14: 0000000000000000 R15: 0000000000000000
> arch_safe_halt arch/x86/include/asm/paravirt.h:94 [inline]
> default_idle+0xbf/0x490 arch/x86/kernel/process.c:498
> arch_cpu_idle+0x10/0x20 arch/x86/kernel/process.c:489
> default_idle_call+0x6d/0x90 kernel/sched/idle.c:93
> cpuidle_idle_call kernel/sched/idle.c:153 [inline]
> do_idle+0x3db/0x5b0 kernel/sched/idle.c:262
> cpu_startup_entry+0x10c/0x120 kernel/sched/idle.c:368
> rest_init+0xe2/0xe5 init/main.c:442
> start_kernel+0x8f4/0x92f init/main.c:739
> ? early_idt_handler_common+
>
>
> ---
> 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 syzkaller@googlegroups.com.
>
> syzbot will keep track of this bug report. See:
> https://goo.gl/tpsmEJ#bug-status-tracking for how to communicate with
> syzbot.
> syzbot can test patches for this bug, for details see:
> https://goo.gl/tpsmEJ#testing-patches
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: possible deadlock in free_ioctx_users
2018-09-09 18:41 possible deadlock in free_ioctx_users syzbot
2018-09-09 19:11 ` Matthew Wilcox
@ 2018-09-10 9:28 ` Miklos Szeredi
2018-09-10 9:43 ` Dmitry Vyukov
1 sibling, 1 reply; 6+ messages in thread
From: Miklos Szeredi @ 2018-09-10 9:28 UTC (permalink / raw)
To: syzbot
Cc: bcrl, linux-aio, linux-fsdevel, linux-kernel, syzkaller-bugs, Al Viro
On Sun, Sep 9, 2018 at 8:41 PM, syzbot
<syzbot+d86c4426a01f60feddc7@syzkaller.appspotmail.com> wrote:
> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit: f8f65382c98a Merge tag 'for-linus' of git://git.kernel.org..
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=113260ae400000
> kernel config: https://syzkaller.appspot.com/x/.config?x=8f59875069d721b6
> dashboard link: https://syzkaller.appspot.com/bug?extid=d86c4426a01f60feddc7
> compiler: gcc (GCC) 8.0.1 20180413 (experimental)
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=120baa9e400000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13979cbe400000
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+d86c4426a01f60feddc7@syzkaller.appspotmail.com
>
> random: sshd: uninitialized urandom read (32 bytes read)
> random: sshd: uninitialized urandom read (32 bytes read)
> random: sshd: uninitialized urandom read (32 bytes read)
>
> ========================================================
> WARNING: possible irq lock inversion dependency detected
> 4.19.0-rc2+ #229 Not tainted
> --------------------------------------------------------
> swapper/0/0 just changed the state of lock:
> 00000000c02bddef (&(&ctx->ctx_lock)->rlock){..-.}, at: spin_lock_irq
> include/linux/spinlock.h:354 [inline]
> 00000000c02bddef (&(&ctx->ctx_lock)->rlock){..-.}, at:
> free_ioctx_users+0xbc/0x710 fs/aio.c:603
> but this lock took another, SOFTIRQ-unsafe lock in the past:
> (&fiq->waitq){+.+.}
>
>
> and interrupts could create inverse lock ordering between them.
>
>
> other info that might help us debug this:
> Possible interrupt unsafe locking scenario:
>
> CPU0 CPU1
> ---- ----
> lock(&fiq->waitq);
> local_irq_disable();
> lock(&(&ctx->ctx_lock)->rlock);
> lock(&fiq->waitq);
> <Interrupt>
> lock(&(&ctx->ctx_lock)->rlock);
Fuse device doesn't support AIO ops. So false positive, AFAICS.
Thanks,
Miklos
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: possible deadlock in free_ioctx_users
2018-09-10 9:28 ` Miklos Szeredi
@ 2018-09-10 9:43 ` Dmitry Vyukov
2018-09-10 9:50 ` Miklos Szeredi
0 siblings, 1 reply; 6+ messages in thread
From: Dmitry Vyukov @ 2018-09-10 9:43 UTC (permalink / raw)
To: Miklos Szeredi
Cc: syzbot, bcrl, linux-aio, linux-fsdevel, LKML, syzkaller-bugs, Al Viro
On Mon, Sep 10, 2018 at 11:28 AM, Miklos Szeredi <miklos@szeredi.hu> wrote:
> On Sun, Sep 9, 2018 at 8:41 PM, syzbot
> <syzbot+d86c4426a01f60feddc7@syzkaller.appspotmail.com> wrote:
>> Hello,
>>
>> syzbot found the following crash on:
>>
>> HEAD commit: f8f65382c98a Merge tag 'for-linus' of git://git.kernel.org..
>> git tree: upstream
>> console output: https://syzkaller.appspot.com/x/log.txt?x=113260ae400000
>> kernel config: https://syzkaller.appspot.com/x/.config?x=8f59875069d721b6
>> dashboard link: https://syzkaller.appspot.com/bug?extid=d86c4426a01f60feddc7
>> compiler: gcc (GCC) 8.0.1 20180413 (experimental)
>> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=120baa9e400000
>> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13979cbe400000
>>
>> IMPORTANT: if you fix the bug, please add the following tag to the commit:
>> Reported-by: syzbot+d86c4426a01f60feddc7@syzkaller.appspotmail.com
>>
>> random: sshd: uninitialized urandom read (32 bytes read)
>> random: sshd: uninitialized urandom read (32 bytes read)
>> random: sshd: uninitialized urandom read (32 bytes read)
>>
>> ========================================================
>> WARNING: possible irq lock inversion dependency detected
>> 4.19.0-rc2+ #229 Not tainted
>> --------------------------------------------------------
>> swapper/0/0 just changed the state of lock:
>> 00000000c02bddef (&(&ctx->ctx_lock)->rlock){..-.}, at: spin_lock_irq
>> include/linux/spinlock.h:354 [inline]
>> 00000000c02bddef (&(&ctx->ctx_lock)->rlock){..-.}, at:
>> free_ioctx_users+0xbc/0x710 fs/aio.c:603
>> but this lock took another, SOFTIRQ-unsafe lock in the past:
>> (&fiq->waitq){+.+.}
>>
>>
>> and interrupts could create inverse lock ordering between them.
>>
>>
>> other info that might help us debug this:
>> Possible interrupt unsafe locking scenario:
>>
>> CPU0 CPU1
>> ---- ----
>> lock(&fiq->waitq);
>> local_irq_disable();
>> lock(&(&ctx->ctx_lock)->rlock);
>> lock(&fiq->waitq);
>> <Interrupt>
>> lock(&(&ctx->ctx_lock)->rlock);
>
> Fuse device doesn't support AIO ops. So false positive, AFAICS.
Hi Miklos,
We still need to annotate this. How?
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: possible deadlock in free_ioctx_users
2018-09-10 9:43 ` Dmitry Vyukov
@ 2018-09-10 9:50 ` Miklos Szeredi
2018-09-10 10:03 ` Dmitry Vyukov
0 siblings, 1 reply; 6+ messages in thread
From: Miklos Szeredi @ 2018-09-10 9:50 UTC (permalink / raw)
To: Dmitry Vyukov
Cc: syzbot, bcrl, linux-aio, linux-fsdevel, LKML, syzkaller-bugs, Al Viro
On Mon, Sep 10, 2018 at 11:43 AM, Dmitry Vyukov <dvyukov@google.com> wrote:
> On Mon, Sep 10, 2018 at 11:28 AM, Miklos Szeredi <miklos@szeredi.hu> wrote:
>> On Sun, Sep 9, 2018 at 8:41 PM, syzbot
>> <syzbot+d86c4426a01f60feddc7@syzkaller.appspotmail.com> wrote:
>>> Hello,
>>>
>>> syzbot found the following crash on:
>>>
>>> HEAD commit: f8f65382c98a Merge tag 'for-linus' of git://git.kernel.org..
>>> git tree: upstream
>>> console output: https://syzkaller.appspot.com/x/log.txt?x=113260ae400000
>>> kernel config: https://syzkaller.appspot.com/x/.config?x=8f59875069d721b6
>>> dashboard link: https://syzkaller.appspot.com/bug?extid=d86c4426a01f60feddc7
>>> compiler: gcc (GCC) 8.0.1 20180413 (experimental)
>>> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=120baa9e400000
>>> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13979cbe400000
>>>
>>> IMPORTANT: if you fix the bug, please add the following tag to the commit:
>>> Reported-by: syzbot+d86c4426a01f60feddc7@syzkaller.appspotmail.com
>>>
>>> random: sshd: uninitialized urandom read (32 bytes read)
>>> random: sshd: uninitialized urandom read (32 bytes read)
>>> random: sshd: uninitialized urandom read (32 bytes read)
>>>
>>> ========================================================
>>> WARNING: possible irq lock inversion dependency detected
>>> 4.19.0-rc2+ #229 Not tainted
>>> --------------------------------------------------------
>>> swapper/0/0 just changed the state of lock:
>>> 00000000c02bddef (&(&ctx->ctx_lock)->rlock){..-.}, at: spin_lock_irq
>>> include/linux/spinlock.h:354 [inline]
>>> 00000000c02bddef (&(&ctx->ctx_lock)->rlock){..-.}, at:
>>> free_ioctx_users+0xbc/0x710 fs/aio.c:603
>>> but this lock took another, SOFTIRQ-unsafe lock in the past:
>>> (&fiq->waitq){+.+.}
>>>
>>>
>>> and interrupts could create inverse lock ordering between them.
>>>
>>>
>>> other info that might help us debug this:
>>> Possible interrupt unsafe locking scenario:
>>>
>>> CPU0 CPU1
>>> ---- ----
>>> lock(&fiq->waitq);
>>> local_irq_disable();
>>> lock(&(&ctx->ctx_lock)->rlock);
>>> lock(&fiq->waitq);
>>> <Interrupt>
>>> lock(&(&ctx->ctx_lock)->rlock);
>>
>> Fuse device doesn't support AIO ops. So false positive, AFAICS.
>
> Hi Miklos,
>
> We still need to annotate this. How?
Good question.
Isn't lockdep assuming too much here? It hasn't shown that that
ctx_lock instance was actually called from interrupt context, has it?
Thanks,
Miklos
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: possible deadlock in free_ioctx_users
2018-09-10 9:50 ` Miklos Szeredi
@ 2018-09-10 10:03 ` Dmitry Vyukov
0 siblings, 0 replies; 6+ messages in thread
From: Dmitry Vyukov @ 2018-09-10 10:03 UTC (permalink / raw)
To: Miklos Szeredi, Peter Zijlstra, Ingo Molnar, Will Deacon
Cc: syzbot, bcrl, linux-aio, linux-fsdevel, LKML, syzkaller-bugs, Al Viro
On Mon, Sep 10, 2018 at 11:50 AM, Miklos Szeredi <miklos@szeredi.hu> wrote:
> On Mon, Sep 10, 2018 at 11:43 AM, Dmitry Vyukov <dvyukov@google.com> wrote:
>> On Mon, Sep 10, 2018 at 11:28 AM, Miklos Szeredi <miklos@szeredi.hu> wrote:
>>> On Sun, Sep 9, 2018 at 8:41 PM, syzbot
>>> <syzbot+d86c4426a01f60feddc7@syzkaller.appspotmail.com> wrote:
>>>> Hello,
>>>>
>>>> syzbot found the following crash on:
>>>>
>>>> HEAD commit: f8f65382c98a Merge tag 'for-linus' of git://git.kernel.org..
>>>> git tree: upstream
>>>> console output: https://syzkaller.appspot.com/x/log.txt?x=113260ae400000
>>>> kernel config: https://syzkaller.appspot.com/x/.config?x=8f59875069d721b6
>>>> dashboard link: https://syzkaller.appspot.com/bug?extid=d86c4426a01f60feddc7
>>>> compiler: gcc (GCC) 8.0.1 20180413 (experimental)
>>>> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=120baa9e400000
>>>> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13979cbe400000
>>>>
>>>> IMPORTANT: if you fix the bug, please add the following tag to the commit:
>>>> Reported-by: syzbot+d86c4426a01f60feddc7@syzkaller.appspotmail.com
>>>>
>>>> random: sshd: uninitialized urandom read (32 bytes read)
>>>> random: sshd: uninitialized urandom read (32 bytes read)
>>>> random: sshd: uninitialized urandom read (32 bytes read)
>>>>
>>>> ========================================================
>>>> WARNING: possible irq lock inversion dependency detected
>>>> 4.19.0-rc2+ #229 Not tainted
>>>> --------------------------------------------------------
>>>> swapper/0/0 just changed the state of lock:
>>>> 00000000c02bddef (&(&ctx->ctx_lock)->rlock){..-.}, at: spin_lock_irq
>>>> include/linux/spinlock.h:354 [inline]
>>>> 00000000c02bddef (&(&ctx->ctx_lock)->rlock){..-.}, at:
>>>> free_ioctx_users+0xbc/0x710 fs/aio.c:603
>>>> but this lock took another, SOFTIRQ-unsafe lock in the past:
>>>> (&fiq->waitq){+.+.}
>>>>
>>>>
>>>> and interrupts could create inverse lock ordering between them.
>>>>
>>>>
>>>> other info that might help us debug this:
>>>> Possible interrupt unsafe locking scenario:
>>>>
>>>> CPU0 CPU1
>>>> ---- ----
>>>> lock(&fiq->waitq);
>>>> local_irq_disable();
>>>> lock(&(&ctx->ctx_lock)->rlock);
>>>> lock(&fiq->waitq);
>>>> <Interrupt>
>>>> lock(&(&ctx->ctx_lock)->rlock);
>>>
>>> Fuse device doesn't support AIO ops. So false positive, AFAICS.
>>
>> Hi Miklos,
>>
>> We still need to annotate this. How?
>
> Good question.
>
> Isn't lockdep assuming too much here? It hasn't shown that that
> ctx_lock instance was actually called from interrupt context, has it?
+lockdep maintainers for lockdep false positive and how to annotate it
Full reports are available here:
https://syzkaller.appspot.com/bug?extid=d86c4426a01f60feddc7
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2018-09-10 10:04 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2018-09-09 18:41 possible deadlock in free_ioctx_users syzbot
2018-09-09 19:11 ` Matthew Wilcox
2018-09-10 9:28 ` Miklos Szeredi
2018-09-10 9:43 ` Dmitry Vyukov
2018-09-10 9:50 ` Miklos Szeredi
2018-09-10 10:03 ` Dmitry Vyukov
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