From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-io1-f69.google.com ([209.85.166.69]:50167 "EHLO mail-io1-f69.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726610AbeJ0Oz5 (ORCPT ); Sat, 27 Oct 2018 10:55:57 -0400 Received: by mail-io1-f69.google.com with SMTP id v23-v6so3002004ioh.16 for ; Fri, 26 Oct 2018 23:16:04 -0700 (PDT) MIME-Version: 1.0 Date: Fri, 26 Oct 2018 23:16:03 -0700 In-Reply-To: <000000000000cbb35d05757f7a3a@google.com> Message-ID: <00000000000046f84d05792fc5f0@google.com> Subject: Re: possible deadlock in aio_poll From: syzbot To: aarcange@redhat.com, akpm@linux-foundation.org, bcrl@kvack.org, hch@infradead.org, linux-aio@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, miklos@szeredi.hu, syzkaller-bugs@googlegroups.com, viro@zeniv.linux.org.uk Content-Type: text/plain; charset="UTF-8"; format=flowed; delsp=yes Sender: linux-fsdevel-owner@vger.kernel.org List-ID: syzbot has found a reproducer for the following crash on: HEAD commit: 18d0eae30e6a Merge tag 'char-misc-4.20-rc1' of git://git.k.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=14728be5400000 kernel config: https://syzkaller.appspot.com/x/.config?x=342f43de913c81b9 dashboard link: https://syzkaller.appspot.com/bug?extid=5b1df0420c523b45a953 compiler: gcc (GCC) 8.0.1 20180413 (experimental) syz repro: https://syzkaller.appspot.com/x/repro.syz?x=161d6999400000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=110f4cf5400000 IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+5b1df0420c523b45a953@syzkaller.appspotmail.com ===================================================== WARNING: SOFTIRQ-safe -> SOFTIRQ-unsafe lock order detected 4.19.0+ #84 Not tainted ----------------------------------------------------- syz-executor781/7254 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire: 00000000e70e96f7 (&ctx->fd_wqh){+.+.}, at: spin_lock include/linux/spinlock.h:329 [inline] 00000000e70e96f7 (&ctx->fd_wqh){+.+.}, at: aio_poll+0x760/0x1420 fs/aio.c:1747 and this task is already holding: 000000009957d7d7 (&(&ctx->ctx_lock)->rlock){..-.}, at: spin_lock_irq include/linux/spinlock.h:354 [inline] 000000009957d7d7 (&(&ctx->ctx_lock)->rlock){..-.}, at: aio_poll+0x738/0x1420 fs/aio.c:1746 which would create a new lock dependency: (&(&ctx->ctx_lock)->rlock){..-.} -> (&ctx->fd_wqh){+.+.} but this new dependency connects a SOFTIRQ-irq-safe lock: (&(&ctx->ctx_lock)->rlock){..-.} ... which became SOFTIRQ-irq-safe at: lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3844 __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:285 [inline] percpu_ref_put include/linux/percpu-refcount.h:301 [inline] percpu_ref_call_confirm_rcu lib/percpu-refcount.c:123 [inline] percpu_ref_switch_to_atomic_rcu+0x563/0x730 lib/percpu-refcount.c:158 __rcu_reclaim kernel/rcu/rcu.h:240 [inline] rcu_do_batch kernel/rcu/tree.c:2437 [inline] invoke_rcu_callbacks kernel/rcu/tree.c:2716 [inline] rcu_process_callbacks+0x100a/0x1ac0 kernel/rcu/tree.c:2697 __do_softirq+0x308/0xb7e kernel/softirq.c:292 invoke_softirq kernel/softirq.c:373 [inline] irq_exit+0x17f/0x1c0 kernel/softirq.c:413 exiting_irq arch/x86/include/asm/apic.h:536 [inline] smp_apic_timer_interrupt+0x1cb/0x760 arch/x86/kernel/apic/apic.c:1061 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:801 native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:57 arch_safe_halt arch/x86/include/asm/paravirt.h:151 [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+0x49b/0x5c0 kernel/sched/idle.c:262 cpu_startup_entry+0x18/0x20 kernel/sched/idle.c:353 start_secondary+0x487/0x5f0 arch/x86/kernel/smpboot.c:271 secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:243 to a SOFTIRQ-irq-unsafe lock: (&ctx->fd_wqh){+.+.} ... which became SOFTIRQ-irq-unsafe at: ... lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3844 __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] userfaultfd_ctx_read+0x2e4/0x2180 fs/userfaultfd.c:1029 userfaultfd_read+0x1e2/0x2c0 fs/userfaultfd.c:1191 __vfs_read+0x117/0x9b0 fs/read_write.c:416 vfs_read+0x17f/0x3c0 fs/read_write.c:452 ksys_read+0x101/0x260 fs/read_write.c:578 __do_sys_read fs/read_write.c:588 [inline] __se_sys_read fs/read_write.c:586 [inline] __x64_sys_read+0x73/0xb0 fs/read_write.c:586 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe other info that might help us debug this: Possible interrupt unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&ctx->fd_wqh); local_irq_disable(); lock(&(&ctx->ctx_lock)->rlock); lock(&ctx->fd_wqh); lock(&(&ctx->ctx_lock)->rlock); *** DEADLOCK *** 1 lock held by syz-executor781/7254: #0: 000000009957d7d7 (&(&ctx->ctx_lock)->rlock){..-.}, at: spin_lock_irq include/linux/spinlock.h:354 [inline] #0: 000000009957d7d7 (&(&ctx->ctx_lock)->rlock){..-.}, at: aio_poll+0x738/0x1420 fs/aio.c:1746 the dependencies between SOFTIRQ-irq-safe lock and the holding lock: -> (&(&ctx->ctx_lock)->rlock){..-.} { IN-SOFTIRQ-W at: lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3844 __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:285 [inline] percpu_ref_put include/linux/percpu-refcount.h:301 [inline] percpu_ref_call_confirm_rcu lib/percpu-refcount.c:123 [inline] percpu_ref_switch_to_atomic_rcu+0x563/0x730 lib/percpu-refcount.c:158 __rcu_reclaim kernel/rcu/rcu.h:240 [inline] rcu_do_batch kernel/rcu/tree.c:2437 [inline] invoke_rcu_callbacks kernel/rcu/tree.c:2716 [inline] rcu_process_callbacks+0x100a/0x1ac0 kernel/rcu/tree.c:2697 __do_softirq+0x308/0xb7e kernel/softirq.c:292 invoke_softirq kernel/softirq.c:373 [inline] irq_exit+0x17f/0x1c0 kernel/softirq.c:413 exiting_irq arch/x86/include/asm/apic.h:536 [inline] smp_apic_timer_interrupt+0x1cb/0x760 arch/x86/kernel/apic/apic.c:1061 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:801 native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:57 arch_safe_halt arch/x86/include/asm/paravirt.h:151 [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+0x49b/0x5c0 kernel/sched/idle.c:262 cpu_startup_entry+0x18/0x20 kernel/sched/idle.c:353 start_secondary+0x487/0x5f0 arch/x86/kernel/smpboot.c:271 secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:243 INITIAL USE at: lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3844 __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:285 [inline] percpu_ref_put include/linux/percpu-refcount.h:301 [inline] percpu_ref_call_confirm_rcu lib/percpu-refcount.c:123 [inline] percpu_ref_switch_to_atomic_rcu+0x563/0x730 lib/percpu-refcount.c:158 __rcu_reclaim kernel/rcu/rcu.h:240 [inline] rcu_do_batch kernel/rcu/tree.c:2437 [inline] invoke_rcu_callbacks kernel/rcu/tree.c:2716 [inline] rcu_process_callbacks+0x100a/0x1ac0 kernel/rcu/tree.c:2697 __do_softirq+0x308/0xb7e kernel/softirq.c:292 invoke_softirq kernel/softirq.c:373 [inline] irq_exit+0x17f/0x1c0 kernel/softirq.c:413 exiting_irq arch/x86/include/asm/apic.h:536 [inline] smp_apic_timer_interrupt+0x1cb/0x760 arch/x86/kernel/apic/apic.c:1061 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:801 native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:57 arch_safe_halt arch/x86/include/asm/paravirt.h:151 [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+0x49b/0x5c0 kernel/sched/idle.c:262 cpu_startup_entry+0x18/0x20 kernel/sched/idle.c:353 start_secondary+0x487/0x5f0 arch/x86/kernel/smpboot.c:271 secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:243 } ... key at: [] __key.50623+0x0/0x40 ... acquired at: lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3844 __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+0xa49/0xf80 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+0x1b7/0x580 fs/aio.c:1887 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe the dependencies between the lock to be acquired and SOFTIRQ-irq-unsafe lock: -> (&ctx->fd_wqh){+.+.} { HARDIRQ-ON-W at: lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3844 __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] userfaultfd_ctx_read+0x2e4/0x2180 fs/userfaultfd.c:1029 userfaultfd_read+0x1e2/0x2c0 fs/userfaultfd.c:1191 __vfs_read+0x117/0x9b0 fs/read_write.c:416 vfs_read+0x17f/0x3c0 fs/read_write.c:452 ksys_read+0x101/0x260 fs/read_write.c:578 __do_sys_read fs/read_write.c:588 [inline] __se_sys_read fs/read_write.c:586 [inline] __x64_sys_read+0x73/0xb0 fs/read_write.c:586 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:3844 __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] userfaultfd_ctx_read+0x2e4/0x2180 fs/userfaultfd.c:1029 userfaultfd_read+0x1e2/0x2c0 fs/userfaultfd.c:1191 __vfs_read+0x117/0x9b0 fs/read_write.c:416 vfs_read+0x17f/0x3c0 fs/read_write.c:452 ksys_read+0x101/0x260 fs/read_write.c:578 __do_sys_read fs/read_write.c:588 [inline] __se_sys_read fs/read_write.c:586 [inline] __x64_sys_read+0x73/0xb0 fs/read_write.c:586 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:3844 __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] userfaultfd_ctx_read+0x2e4/0x2180 fs/userfaultfd.c:1029 userfaultfd_read+0x1e2/0x2c0 fs/userfaultfd.c:1191 __vfs_read+0x117/0x9b0 fs/read_write.c:416 vfs_read+0x17f/0x3c0 fs/read_write.c:452 ksys_read+0x101/0x260 fs/read_write.c:578 __do_sys_read fs/read_write.c:588 [inline] __se_sys_read fs/read_write.c:586 [inline] __x64_sys_read+0x73/0xb0 fs/read_write.c:586 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe } ... key at: [] __key.44253+0x0/0x40 ... acquired at: lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3844 __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+0xa49/0xf80 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+0x1b7/0x580 fs/aio.c:1887 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe stack backtrace: CPU: 0 PID: 7254 Comm: syz-executor781 Not tainted 4.19.0+ #84 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+0x244/0x39d lib/dump_stack.c:113 print_bad_irq_dependency kernel/locking/lockdep.c:1570 [inline] check_usage.cold.58+0x6d5/0xad1 kernel/locking/lockdep.c:1602 check_irq_usage kernel/locking/lockdep.c:1658 [inline] check_prev_add_irq kernel/locking/lockdep_states.h:8 [inline] check_prev_add kernel/locking/lockdep.c:1868 [inline] check_prevs_add kernel/locking/lockdep.c:1976 [inline] validate_chain kernel/locking/lockdep.c:2347 [inline] __lock_acquire+0x238a/0x4c20 kernel/locking/lockdep.c:3341 lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3844 __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+0xa49/0xf80 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+0x1b7/0x580 fs/aio.c:1887 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x447dc9 Code: e8 9c ba 02 00 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 5b 07 fc ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007fc840e69da8 EFLAGS: 00000293 ORIG_RAX: 00000000000000d1 RAX: ffffffffffffffda RBX: 00000000006e39e8 RCX: 0000000000447dc9 RDX: 0000000020000b00 RSI: 0000000000000001 RDI: 00007fc840e39000 RBP: 00000000006e39e0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000293 R12: 00000000006e39ec R13: 702f74656e2f666c R14: 65732f636f72702f R15: 0000000000000000