Re: possible deadlock in io_submit_one (3)

From: syzbot
Date: Mon Apr 06 2020 - 21:36:17 EST

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syzbot has found a reproducer for the following crash on:

HEAD commit: 7e634208 Merge tag 'acpi-5.7-rc1-2' of git://git.kernel.or..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=139b71c7e00000
kernel config: https://syzkaller.appspot.com/x/.config?x=12205d036cec317f
dashboard link: https://syzkaller.appspot.com/bug?extid=343f75cdeea091340956
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
userspace arch: i386
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=105d592be00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+343f75cdeea091340956@xxxxxxxxxxxxxxxxxxxxxxxxx

=====================================================
WARNING: SOFTIRQ-safe -> SOFTIRQ-unsafe lock order detected
5.6.0-syzkaller #0 Not tainted
-----------------------------------------------------
syz-executor.0/9005 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire:
ffff88808b9c1b48 (&pid->wait_pidfd){+.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:353 [inline]
ffff88808b9c1b48 (&pid->wait_pidfd){+.+.}-{2:2}, at: aio_poll fs/aio.c:1767 [inline]
ffff88808b9c1b48 (&pid->wait_pidfd){+.+.}-{2:2}, at: __io_submit_one fs/aio.c:1841 [inline]
ffff88808b9c1b48 (&pid->wait_pidfd){+.+.}-{2:2}, at: io_submit_one+0xc1b/0x2ec0 fs/aio.c:1878

and this task is already holding:
ffff8880a81b1cd8 (&ctx->ctx_lock){..-.}-{2:2}, at: spin_lock_irq include/linux/spinlock.h:378 [inline]
ffff8880a81b1cd8 (&ctx->ctx_lock){..-.}-{2:2}, at: aio_poll fs/aio.c:1765 [inline]
ffff8880a81b1cd8 (&ctx->ctx_lock){..-.}-{2:2}, at: __io_submit_one fs/aio.c:1841 [inline]
ffff8880a81b1cd8 (&ctx->ctx_lock){..-.}-{2:2}, at: io_submit_one+0xbd6/0x2ec0 fs/aio.c:1878
which would create a new lock dependency:
(&ctx->ctx_lock){..-.}-{2:2} -> (&pid->wait_pidfd){+.+.}-{2:2}

but this new dependency connects a SOFTIRQ-irq-safe lock:
(&ctx->ctx_lock){..-.}-{2:2}

... which became SOFTIRQ-irq-safe at:
lock_acquire+0x1f2/0x8f0 kernel/locking/lockdep.c:4923
__raw_spin_lock_irq include/linux/spinlock_api_smp.h:128 [inline]
_raw_spin_lock_irq+0x5b/0x80 kernel/locking/spinlock.c:167
spin_lock_irq include/linux/spinlock.h:378 [inline]
free_ioctx_users+0x2b/0x450 fs/aio.c:618
percpu_ref_put_many include/linux/percpu-refcount.h:309 [inline]
percpu_ref_put include/linux/percpu-refcount.h:325 [inline]
percpu_ref_call_confirm_rcu lib/percpu-refcount.c:131 [inline]
percpu_ref_switch_to_atomic_rcu+0x494/0x540 lib/percpu-refcount.c:166
rcu_do_batch kernel/rcu/tree.c:2206 [inline]
rcu_core+0x59f/0x1370 kernel/rcu/tree.c:2433
__do_softirq+0x26c/0x9f7 kernel/softirq.c:292
invoke_softirq kernel/softirq.c:373 [inline]
irq_exit+0x192/0x1d0 kernel/softirq.c:413
exiting_irq arch/x86/include/asm/apic.h:546 [inline]
smp_apic_timer_interrupt+0x19e/0x600 arch/x86/kernel/apic/apic.c:1140
apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829
preempt_count_add+0x0/0x140 kernel/sched/core.c:6758
__raw_spin_lock include/linux/spinlock_api_smp.h:141 [inline]
_raw_spin_lock+0xe/0x40 kernel/locking/spinlock.c:151
spin_lock include/linux/spinlock.h:353 [inline]
lockref_put_or_lock+0x14/0x80 lib/lockref.c:174
fast_dput fs/dcache.c:728 [inline]
dput+0x4a3/0xdf0 fs/dcache.c:846
path_put+0x2d/0x60 fs/namei.c:482
vfs_statx+0x14d/0x1e0 fs/stat.c:202
vfs_stat include/linux/fs.h:3279 [inline]
__do_sys_newstat+0x96/0x120 fs/stat.c:351
do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295
entry_SYSCALL_64_after_hwframe+0x49/0xb3

to a SOFTIRQ-irq-unsafe lock:
(&pid->wait_pidfd){+.+.}-{2:2}

... which became SOFTIRQ-irq-unsafe at:
...
lock_acquire+0x1f2/0x8f0 kernel/locking/lockdep.c:4923
__raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
_raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:151
spin_lock include/linux/spinlock.h:353 [inline]
proc_pid_make_inode+0x1f9/0x3c0 fs/proc/base.c:1880
proc_pid_instantiate+0x51/0x150 fs/proc/base.c:3285
proc_pid_lookup+0x1da/0x340 fs/proc/base.c:3320
proc_root_lookup+0x20/0x60 fs/proc/root.c:243
__lookup_slow+0x256/0x490 fs/namei.c:1530
lookup_slow fs/namei.c:1547 [inline]
walk_component+0x418/0x6a0 fs/namei.c:1846
link_path_walk.part.0+0x4f1/0xb50 fs/namei.c:2166
link_path_walk fs/namei.c:2098 [inline]
path_openat+0x25a/0x27d0 fs/namei.c:3342
do_filp_open+0x192/0x260 fs/namei.c:3373
do_sys_openat2+0x585/0x7d0 fs/open.c:1148
do_sys_open+0xc3/0x140 fs/open.c:1164
do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295
entry_SYSCALL_64_after_hwframe+0x49/0xb3

other info that might help us debug this:

Possible interrupt unsafe locking scenario:

CPU0 CPU1
---- ----
lock(&pid->wait_pidfd);
local_irq_disable();
lock(&ctx->ctx_lock);
lock(&pid->wait_pidfd);
<Interrupt>
lock(&ctx->ctx_lock);

*** DEADLOCK ***

1 lock held by syz-executor.0/9005:
#0: ffff8880a81b1cd8 (&ctx->ctx_lock){..-.}-{2:2}, at: spin_lock_irq include/linux/spinlock.h:378 [inline]
#0: ffff8880a81b1cd8 (&ctx->ctx_lock){..-.}-{2:2}, at: aio_poll fs/aio.c:1765 [inline]
#0: ffff8880a81b1cd8 (&ctx->ctx_lock){..-.}-{2:2}, at: __io_submit_one fs/aio.c:1841 [inline]
#0: ffff8880a81b1cd8 (&ctx->ctx_lock){..-.}-{2:2}, at: io_submit_one+0xbd6/0x2ec0 fs/aio.c:1878

the dependencies between SOFTIRQ-irq-safe lock and the holding lock:
-> (&ctx->ctx_lock){..-.}-{2:2} {
IN-SOFTIRQ-W at:
lock_acquire+0x1f2/0x8f0 kernel/locking/lockdep.c:4923
__raw_spin_lock_irq include/linux/spinlock_api_smp.h:128 [inline]
_raw_spin_lock_irq+0x5b/0x80 kernel/locking/spinlock.c:167
spin_lock_irq include/linux/spinlock.h:378 [inline]
free_ioctx_users+0x2b/0x450 fs/aio.c:618
percpu_ref_put_many include/linux/percpu-refcount.h:309 [inline]
percpu_ref_put include/linux/percpu-refcount.h:325 [inline]
percpu_ref_call_confirm_rcu lib/percpu-refcount.c:131 [inline]
percpu_ref_switch_to_atomic_rcu+0x494/0x540 lib/percpu-refcount.c:166
rcu_do_batch kernel/rcu/tree.c:2206 [inline]
rcu_core+0x59f/0x1370 kernel/rcu/tree.c:2433
__do_softirq+0x26c/0x9f7 kernel/softirq.c:292
invoke_softirq kernel/softirq.c:373 [inline]
irq_exit+0x192/0x1d0 kernel/softirq.c:413
exiting_irq arch/x86/include/asm/apic.h:546 [inline]
smp_apic_timer_interrupt+0x19e/0x600 arch/x86/kernel/apic/apic.c:1140
apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829
preempt_count_add+0x0/0x140 kernel/sched/core.c:6758
__raw_spin_lock include/linux/spinlock_api_smp.h:141 [inline]
_raw_spin_lock+0xe/0x40 kernel/locking/spinlock.c:151
spin_lock include/linux/spinlock.h:353 [inline]
lockref_put_or_lock+0x14/0x80 lib/lockref.c:174
fast_dput fs/dcache.c:728 [inline]
dput+0x4a3/0xdf0 fs/dcache.c:846
path_put+0x2d/0x60 fs/namei.c:482
vfs_statx+0x14d/0x1e0 fs/stat.c:202
vfs_stat include/linux/fs.h:3279 [inline]
__do_sys_newstat+0x96/0x120 fs/stat.c:351
do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295
entry_SYSCALL_64_after_hwframe+0x49/0xb3
INITIAL USE at:
lock_acquire+0x1f2/0x8f0 kernel/locking/lockdep.c:4923
__raw_spin_lock_irq include/linux/spinlock_api_smp.h:128 [inline]
_raw_spin_lock_irq+0x5b/0x80 kernel/locking/spinlock.c:167
spin_lock_irq include/linux/spinlock.h:378 [inline]
free_ioctx_users+0x2b/0x450 fs/aio.c:618
percpu_ref_put_many include/linux/percpu-refcount.h:309 [inline]
percpu_ref_put include/linux/percpu-refcount.h:325 [inline]
percpu_ref_call_confirm_rcu lib/percpu-refcount.c:131 [inline]
percpu_ref_switch_to_atomic_rcu+0x494/0x540 lib/percpu-refcount.c:166
rcu_do_batch kernel/rcu/tree.c:2206 [inline]
rcu_core+0x59f/0x1370 kernel/rcu/tree.c:2433
__do_softirq+0x26c/0x9f7 kernel/softirq.c:292
invoke_softirq kernel/softirq.c:373 [inline]
irq_exit+0x192/0x1d0 kernel/softirq.c:413
exiting_irq arch/x86/include/asm/apic.h:546 [inline]
smp_apic_timer_interrupt+0x19e/0x600 arch/x86/kernel/apic/apic.c:1140
apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829
preempt_count_add+0x0/0x140 kernel/sched/core.c:6758
__raw_spin_lock include/linux/spinlock_api_smp.h:141 [inline]
_raw_spin_lock+0xe/0x40 kernel/locking/spinlock.c:151
spin_lock include/linux/spinlock.h:353 [inline]
lockref_put_or_lock+0x14/0x80 lib/lockref.c:174
fast_dput fs/dcache.c:728 [inline]
dput+0x4a3/0xdf0 fs/dcache.c:846
path_put+0x2d/0x60 fs/namei.c:482
vfs_statx+0x14d/0x1e0 fs/stat.c:202
vfs_stat include/linux/fs.h:3279 [inline]
__do_sys_newstat+0x96/0x120 fs/stat.c:351
do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295
entry_SYSCALL_64_after_hwframe+0x49/0xb3
}
... key at: [<ffffffff8c67af20>] __key.55262+0x0/0x40
... acquired at:
lock_acquire+0x1f2/0x8f0 kernel/locking/lockdep.c:4923
__raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
_raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:151
spin_lock include/linux/spinlock.h:353 [inline]
aio_poll fs/aio.c:1767 [inline]
__io_submit_one fs/aio.c:1841 [inline]
io_submit_one+0xc1b/0x2ec0 fs/aio.c:1878
__do_compat_sys_io_submit fs/aio.c:1979 [inline]
__se_compat_sys_io_submit fs/aio.c:1949 [inline]
__ia32_compat_sys_io_submit+0x1bf/0x530 fs/aio.c:1949
do_syscall_32_irqs_on arch/x86/entry/common.c:337 [inline]
do_fast_syscall_32+0x270/0xe90 arch/x86/entry/common.c:396
entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139

the dependencies between the lock to be acquired
and SOFTIRQ-irq-unsafe lock:
-> (&pid->wait_pidfd){+.+.}-{2:2} {
HARDIRQ-ON-W at:
lock_acquire+0x1f2/0x8f0 kernel/locking/lockdep.c:4923
__raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
_raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:151
spin_lock include/linux/spinlock.h:353 [inline]
proc_pid_make_inode+0x1f9/0x3c0 fs/proc/base.c:1880
proc_pid_instantiate+0x51/0x150 fs/proc/base.c:3285
proc_pid_lookup+0x1da/0x340 fs/proc/base.c:3320
proc_root_lookup+0x20/0x60 fs/proc/root.c:243
__lookup_slow+0x256/0x490 fs/namei.c:1530
lookup_slow fs/namei.c:1547 [inline]
walk_component+0x418/0x6a0 fs/namei.c:1846
link_path_walk.part.0+0x4f1/0xb50 fs/namei.c:2166
link_path_walk fs/namei.c:2098 [inline]
path_openat+0x25a/0x27d0 fs/namei.c:3342
do_filp_open+0x192/0x260 fs/namei.c:3373
do_sys_openat2+0x585/0x7d0 fs/open.c:1148
do_sys_open+0xc3/0x140 fs/open.c:1164
do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295
entry_SYSCALL_64_after_hwframe+0x49/0xb3
SOFTIRQ-ON-W at:
lock_acquire+0x1f2/0x8f0 kernel/locking/lockdep.c:4923
__raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
_raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:151
spin_lock include/linux/spinlock.h:353 [inline]
proc_pid_make_inode+0x1f9/0x3c0 fs/proc/base.c:1880
proc_pid_instantiate+0x51/0x150 fs/proc/base.c:3285
proc_pid_lookup+0x1da/0x340 fs/proc/base.c:3320
proc_root_lookup+0x20/0x60 fs/proc/root.c:243
__lookup_slow+0x256/0x490 fs/namei.c:1530
lookup_slow fs/namei.c:1547 [inline]
walk_component+0x418/0x6a0 fs/namei.c:1846
link_path_walk.part.0+0x4f1/0xb50 fs/namei.c:2166
link_path_walk fs/namei.c:2098 [inline]
path_openat+0x25a/0x27d0 fs/namei.c:3342
do_filp_open+0x192/0x260 fs/namei.c:3373
do_sys_openat2+0x585/0x7d0 fs/open.c:1148
do_sys_open+0xc3/0x140 fs/open.c:1164
do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295
entry_SYSCALL_64_after_hwframe+0x49/0xb3
INITIAL USE at:
lock_acquire+0x1f2/0x8f0 kernel/locking/lockdep.c:4923
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0x8c/0xbf kernel/locking/spinlock.c:159
__wake_up_common_lock+0xb4/0x130 kernel/sched/wait.c:122
do_notify_pidfd kernel/signal.c:1900 [inline]
do_notify_parent+0x19e/0xe60 kernel/signal.c:1927
exit_notify kernel/exit.c:660 [inline]
do_exit+0x238f/0x2dd0 kernel/exit.c:816
call_usermodehelper_exec_async+0x507/0x710 kernel/umh.c:125
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
}
... key at: [<ffffffff8bbbe680>] __key.53786+0x0/0x40
... acquired at:
lock_acquire+0x1f2/0x8f0 kernel/locking/lockdep.c:4923
__raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
_raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:151
spin_lock include/linux/spinlock.h:353 [inline]
aio_poll fs/aio.c:1767 [inline]
__io_submit_one fs/aio.c:1841 [inline]
io_submit_one+0xc1b/0x2ec0 fs/aio.c:1878
__do_compat_sys_io_submit fs/aio.c:1979 [inline]
__se_compat_sys_io_submit fs/aio.c:1949 [inline]
__ia32_compat_sys_io_submit+0x1bf/0x530 fs/aio.c:1949
do_syscall_32_irqs_on arch/x86/entry/common.c:337 [inline]
do_fast_syscall_32+0x270/0xe90 arch/x86/entry/common.c:396
entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139

stack backtrace:
CPU: 0 PID: 9005 Comm: syz-executor.0 Not tainted 5.6.0-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+0x188/0x20d lib/dump_stack.c:118
print_bad_irq_dependency kernel/locking/lockdep.c:2132 [inline]
check_irq_usage.cold+0x566/0x6de kernel/locking/lockdep.c:2330
check_prev_add kernel/locking/lockdep.c:2519 [inline]
check_prevs_add kernel/locking/lockdep.c:2620 [inline]
validate_chain kernel/locking/lockdep.c:3237 [inline]
__lock_acquire+0x2c39/0x4e00 kernel/locking/lockdep.c:4344
lock_acquire+0x1f2/0x8f0 kernel/locking/lockdep.c:4923
__raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
_raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:151
spin_lock include/linux/spinlock.h:353 [inline]
aio_poll fs/aio.c:1767 [inline]
__io_submit_one fs/aio.c:1841 [inline]
io_submit_one+0xc1b/0x2ec0 fs/aio.c:1878
__do_compat_sys_io_submit fs/aio.c:1979 [inline]
__se_compat_sys_io_submit fs/aio.c:1949 [inline]
__ia32_compat_sys_io_submit+0x1bf/0x530 fs/aio.c:1949
do_syscall_32_irqs_on arch/x86/entry/common.c:337 [inline]
do_fast_syscall_32+0x270/0xe90 arch/x86/entry/common.c:396
entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139

Next message: J, KEERTHY: "Re: [PATCH v5 4/4] arm64: dts: ti: am6: Add VTM node"
Previous message: Ricardo Neri: "Re: [PATCH] x86/cpufeatures: Add enumeration for serialize instruction"
In reply to: syzbot: "possible deadlock in io_submit_one (3)"
Next in thread: syzbot: "Re: possible deadlock in io_submit_one (3)"
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