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
