===================================================== WARNING: SOFTIRQ-safe -> SOFTIRQ-unsafe lock order detected 5.2.0-rc7-next-20190703 #28 Not tainted ----------------------------------------------------- syz-executor.2/24310 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire: 00000000085e1791 (&ctx->fault_pending_wqh){+.+.}, at: spin_lock include/linux/spinlock.h:338 [inline] 00000000085e1791 (&ctx->fault_pending_wqh){+.+.}, at: userfaultfd_ctx_read fs/userfaultfd.c:1045 [inline] 00000000085e1791 (&ctx->fault_pending_wqh){+.+.}, at: userfaultfd_read+0x54d/0x1940 fs/userfaultfd.c:1203 and this task is already holding: 00000000c4414e7e (&ctx->fd_wqh){....}, at: spin_lock_irq include/linux/spinlock.h:363 [inline] 00000000c4414e7e (&ctx->fd_wqh){....}, at: userfaultfd_ctx_read fs/userfaultfd.c:1041 [inline] 00000000c4414e7e (&ctx->fd_wqh){....}, at: userfaultfd_read+0x27a/0x1940 fs/userfaultfd.c:1203 which would create a new lock dependency: (&ctx->fd_wqh){....} -> (&ctx->fault_pending_wqh){+.+.} but this new dependency connects a SOFTIRQ-irq-safe lock: (&(&ctx->ctx_lock)->rlock){..-.} ... which became SOFTIRQ-irq-safe at: lock_acquire+0x190/0x410 kernel/locking/lockdep.c:4413 __raw_spin_lock_irq include/linux/spinlock_api_smp.h:128 [inline] _raw_spin_lock_irq+0x60/0x80 kernel/locking/spinlock.c:167 spin_lock_irq include/linux/spinlock.h:363 [inline] free_ioctx_users+0x2d/0x490 fs/aio.c:620 percpu_ref_put_many include/linux/percpu-refcount.h:293 [inline] percpu_ref_put include/linux/percpu-refcount.h:309 [inline] percpu_ref_call_confirm_rcu lib/percpu-refcount.c:130 [inline] percpu_ref_switch_to_atomic_rcu+0x4c0/0x570 lib/percpu-refcount.c:165 __rcu_reclaim kernel/rcu/rcu.h:222 [inline] rcu_do_batch kernel/rcu/tree.c:2114 [inline] rcu_core+0x67f/0x1580 kernel/rcu/tree.c:2314 rcu_core_si+0x9/0x10 kernel/rcu/tree.c:2323 __do_softirq+0x262/0x98c kernel/softirq.c:292 invoke_softirq kernel/softirq.c:373 [inline] irq_exit+0x19b/0x1e0 kernel/softirq.c:413 exiting_irq arch/x86/include/asm/apic.h:537 [inline] smp_apic_timer_interrupt+0x1a3/0x610 arch/x86/kernel/apic/apic.c:1095 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:807 arch_local_irq_restore arch/x86/include/asm/paravirt.h:767 [inline] lock_acquire+0x20b/0x410 kernel/locking/lockdep.c:4416 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock+0x2f/0x40 kernel/locking/spinlock.c:151 spin_lock include/linux/spinlock.h:338 [inline] lockref_get_not_dead+0x19/0x90 lib/lockref.c:211 legitimize_path.isra.0+0x87/0x1c0 fs/namei.c:623 unlazy_walk+0x113/0x560 fs/namei.c:675 complete_walk+0xcf/0x250 fs/namei.c:788 do_last fs/namei.c:3298 [inline] path_openat+0xa32/0x4630 fs/namei.c:3533 do_filp_open+0x1a1/0x280 fs/namei.c:3563 do_sys_open+0x3fe/0x5d0 fs/open.c:1070 __do_sys_open fs/open.c:1088 [inline] __se_sys_open fs/open.c:1083 [inline] __x64_sys_open+0x7e/0xc0 fs/open.c:1083 do_syscall_64+0xfd/0x6a0 arch/x86/entry/common.c:296 entry_SYSCALL_64_after_hwframe+0x49/0xbe to a SOFTIRQ-irq-unsafe lock: (&ctx->fault_pending_wqh){+.+.} ... which became SOFTIRQ-irq-unsafe at: ... lock_acquire+0x190/0x410 kernel/locking/lockdep.c:4413 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock+0x2f/0x40 kernel/locking/spinlock.c:151 spin_lock include/linux/spinlock.h:338 [inline] handle_userfault+0x58e/0x1900 fs/userfaultfd.c:461 do_anonymous_page mm/memory.c:3099 [inline] handle_pte_fault mm/memory.c:3953 [inline] __handle_mm_fault+0x363e/0x3f20 mm/memory.c:4079 handle_mm_fault+0x1b5/0x6b0 mm/memory.c:4116 do_user_addr_fault arch/x86/mm/fault.c:1444 [inline] __do_page_fault+0x536/0xdd0 arch/x86/mm/fault.c:1510 do_page_fault+0x71/0x5e1 arch/x86/mm/fault.c:1541 page_fault+0x1e/0x30 arch/x86/entry/entry_64.S:1161 other info that might help us debug this: Chain exists of: &(&ctx->ctx_lock)->rlock --> &ctx->fd_wqh --> &ctx->fault_pending_wqh Possible interrupt unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&ctx->fault_pending_wqh); local_irq_disable(); lock(&(&ctx->ctx_lock)->rlock); lock(&ctx->fd_wqh); lock(&(&ctx->ctx_lock)->rlock); *** DEADLOCK *** 1 lock held by syz-executor.2/24310: #0: 00000000c4414e7e (&ctx->fd_wqh){....}, at: spin_lock_irq include/linux/spinlock.h:363 [inline] #0: 00000000c4414e7e (&ctx->fd_wqh){....}, at: userfaultfd_ctx_read fs/userfaultfd.c:1041 [inline] #0: 00000000c4414e7e (&ctx->fd_wqh){....}, at: userfaultfd_read+0x27a/0x1940 fs/userfaultfd.c:1203 the dependencies between SOFTIRQ-irq-safe lock and the holding lock: -> (&(&ctx->ctx_lock)->rlock){..-.} { IN-SOFTIRQ-W at: lock_acquire+0x190/0x410 kernel/locking/lockdep.c:4413 __raw_spin_lock_irq include/linux/spinlock_api_smp.h:128 [inline] _raw_spin_lock_irq+0x60/0x80 kernel/locking/spinlock.c:167 spin_lock_irq include/linux/spinlock.h:363 [inline] free_ioctx_users+0x2d/0x490 fs/aio.c:620 percpu_ref_put_many include/linux/percpu-refcount.h:293 [inline] percpu_ref_put include/linux/percpu-refcount.h:309 [inline] percpu_ref_call_confirm_rcu lib/percpu-refcount.c:130 [inline] percpu_ref_switch_to_atomic_rcu+0x4c0/0x570 lib/percpu-refcount.c:165 __rcu_reclaim kernel/rcu/rcu.h:222 [inline] rcu_do_batch kernel/rcu/tree.c:2114 [inline] rcu_core+0x67f/0x1580 kernel/rcu/tree.c:2314 rcu_core_si+0x9/0x10 kernel/rcu/tree.c:2323 __do_softirq+0x262/0x98c kernel/softirq.c:292 invoke_softirq kernel/softirq.c:373 [inline] irq_exit+0x19b/0x1e0 kernel/softirq.c:413 exiting_irq arch/x86/include/asm/apic.h:537 [inline] smp_apic_timer_interrupt+0x1a3/0x610 arch/x86/kernel/apic/apic.c:1095 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:807 arch_local_irq_restore arch/x86/include/asm/paravirt.h:767 [inline] lock_acquire+0x20b/0x410 kernel/locking/lockdep.c:4416 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock+0x2f/0x40 kernel/locking/spinlock.c:151 spin_lock include/linux/spinlock.h:338 [inline] lockref_get_not_dead+0x19/0x90 lib/lockref.c:211 legitimize_path.isra.0+0x87/0x1c0 fs/namei.c:623 unlazy_walk+0x113/0x560 fs/namei.c:675 complete_walk+0xcf/0x250 fs/namei.c:788 do_last fs/namei.c:3298 [inline] path_openat+0xa32/0x4630 fs/namei.c:3533 do_filp_open+0x1a1/0x280 fs/namei.c:3563 do_sys_open+0x3fe/0x5d0 fs/open.c:1070 __do_sys_open fs/open.c:1088 [inline] __se_sys_open fs/open.c:1083 [inline] __x64_sys_open+0x7e/0xc0 fs/open.c:1083 do_syscall_64+0xfd/0x6a0 arch/x86/entry/common.c:296 entry_SYSCALL_64_after_hwframe+0x49/0xbe INITIAL USE at: lock_acquire+0x190/0x410 kernel/locking/lockdep.c:4413 __raw_spin_lock_irq include/linux/spinlock_api_smp.h:128 [inline] _raw_spin_lock_irq+0x60/0x80 kernel/locking/spinlock.c:167 spin_lock_irq include/linux/spinlock.h:363 [inline] free_ioctx_users+0x2d/0x490 fs/aio.c:620 percpu_ref_put_many include/linux/percpu-refcount.h:293 [inline] percpu_ref_put include/linux/percpu-refcount.h:309 [inline] percpu_ref_call_confirm_rcu lib/percpu-refcount.c:130 [inline] percpu_ref_switch_to_atomic_rcu+0x4c0/0x570 lib/percpu-refcount.c:165 __rcu_reclaim kernel/rcu/rcu.h:222 [inline] rcu_do_batch kernel/rcu/tree.c:2114 [inline] rcu_core+0x67f/0x1580 kernel/rcu/tree.c:2314 rcu_core_si+0x9/0x10 kernel/rcu/tree.c:2323 __do_softirq+0x262/0x98c kernel/softirq.c:292 invoke_softirq kernel/softirq.c:373 [inline] irq_exit+0x19b/0x1e0 kernel/softirq.c:413 exiting_irq arch/x86/include/asm/apic.h:537 [inline] smp_apic_timer_interrupt+0x1a3/0x610 arch/x86/kernel/apic/apic.c:1095 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:807 arch_local_irq_restore arch/x86/include/asm/paravirt.h:767 [inline] lock_acquire+0x20b/0x410 kernel/locking/lockdep.c:4416 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock+0x2f/0x40 kernel/locking/spinlock.c:151 spin_lock include/linux/spinlock.h:338 [inline] lockref_get_not_dead+0x19/0x90 lib/lockref.c:211 legitimize_path.isra.0+0x87/0x1c0 fs/namei.c:623 unlazy_walk+0x113/0x560 fs/namei.c:675 complete_walk+0xcf/0x250 fs/namei.c:788 do_last fs/namei.c:3298 [inline] path_openat+0xa32/0x4630 fs/namei.c:3533 do_filp_open+0x1a1/0x280 fs/namei.c:3563 do_sys_open+0x3fe/0x5d0 fs/open.c:1070 __do_sys_open fs/open.c:1088 [inline] __se_sys_open fs/open.c:1083 [inline] __x64_sys_open+0x7e/0xc0 fs/open.c:1083 do_syscall_64+0xfd/0x6a0 arch/x86/entry/common.c:296 entry_SYSCALL_64_after_hwframe+0x49/0xbe } ... key at: [] __key.53855+0x0/0x40 ... acquired at: __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock+0x2f/0x40 kernel/locking/spinlock.c:151 spin_lock include/linux/spinlock.h:338 [inline] aio_poll fs/aio.c:1750 [inline] __io_submit_one fs/aio.c:1824 [inline] io_submit_one+0xefa/0x2ef0 fs/aio.c:1861 __do_sys_io_submit fs/aio.c:1920 [inline] __se_sys_io_submit fs/aio.c:1890 [inline] __x64_sys_io_submit+0x1bd/0x570 fs/aio.c:1890 do_syscall_64+0xfd/0x6a0 arch/x86/entry/common.c:296 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> (&ctx->fd_wqh){....} { INITIAL USE at: lock_acquire+0x190/0x410 kernel/locking/lockdep.c:4413 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x95/0xcd kernel/locking/spinlock.c:159 __wake_up_common_lock+0xc8/0x150 kernel/sched/wait.c:122 __wake_up+0xe/0x10 kernel/sched/wait.c:142 handle_userfault+0x932/0x1900 fs/userfaultfd.c:487 do_anonymous_page mm/memory.c:3099 [inline] handle_pte_fault mm/memory.c:3953 [inline] __handle_mm_fault+0x363e/0x3f20 mm/memory.c:4079 handle_mm_fault+0x1b5/0x6b0 mm/memory.c:4116 do_user_addr_fault arch/x86/mm/fault.c:1444 [inline] __do_page_fault+0x536/0xdd0 arch/x86/mm/fault.c:1510 do_page_fault+0x71/0x5e1 arch/x86/mm/fault.c:1541 page_fault+0x1e/0x30 arch/x86/entry/entry_64.S:1161 } ... key at: [] __key.46575+0x0/0x40 ... acquired at: lock_acquire+0x190/0x410 kernel/locking/lockdep.c:4413 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock+0x2f/0x40 kernel/locking/spinlock.c:151 spin_lock include/linux/spinlock.h:338 [inline] userfaultfd_ctx_read fs/userfaultfd.c:1045 [inline] userfaultfd_read+0x54d/0x1940 fs/userfaultfd.c:1203 __vfs_read+0x8a/0x110 fs/read_write.c:425 vfs_read+0x1f0/0x440 fs/read_write.c:461 ksys_read+0x14f/0x290 fs/read_write.c:587 __do_sys_read fs/read_write.c:597 [inline] __se_sys_read fs/read_write.c:595 [inline] __x64_sys_read+0x73/0xb0 fs/read_write.c:595 do_syscall_64+0xfd/0x6a0 arch/x86/entry/common.c:296 entry_SYSCALL_64_after_hwframe+0x49/0xbe the dependencies between the lock to be acquired and SOFTIRQ-irq-unsafe lock: -> (&ctx->fault_pending_wqh){+.+.} { HARDIRQ-ON-W at: lock_acquire+0x190/0x410 kernel/locking/lockdep.c:4413 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock+0x2f/0x40 kernel/locking/spinlock.c:151 spin_lock include/linux/spinlock.h:338 [inline] handle_userfault+0x58e/0x1900 fs/userfaultfd.c:461 do_anonymous_page mm/memory.c:3099 [inline] handle_pte_fault mm/memory.c:3953 [inline] __handle_mm_fault+0x363e/0x3f20 mm/memory.c:4079 handle_mm_fault+0x1b5/0x6b0 mm/memory.c:4116 do_user_addr_fault arch/x86/mm/fault.c:1444 [inline] __do_page_fault+0x536/0xdd0 arch/x86/mm/fault.c:1510 do_page_fault+0x71/0x5e1 arch/x86/mm/fault.c:1541 page_fault+0x1e/0x30 arch/x86/entry/entry_64.S:1161 SOFTIRQ-ON-W at: lock_acquire+0x190/0x410 kernel/locking/lockdep.c:4413 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock+0x2f/0x40 kernel/locking/spinlock.c:151 spin_lock include/linux/spinlock.h:338 [inline] handle_userfault+0x58e/0x1900 fs/userfaultfd.c:461 do_anonymous_page mm/memory.c:3099 [inline] handle_pte_fault mm/memory.c:3953 [inline] __handle_mm_fault+0x363e/0x3f20 mm/memory.c:4079 handle_mm_fault+0x1b5/0x6b0 mm/memory.c:4116 do_user_addr_fault arch/x86/mm/fault.c:1444 [inline] __do_page_fault+0x536/0xdd0 arch/x86/mm/fault.c:1510 do_page_fault+0x71/0x5e1 arch/x86/mm/fault.c:1541 page_fault+0x1e/0x30 arch/x86/entry/entry_64.S:1161 INITIAL USE at: lock_acquire+0x190/0x410 kernel/locking/lockdep.c:4413 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock+0x2f/0x40 kernel/locking/spinlock.c:151 spin_lock include/linux/spinlock.h:338 [inline] handle_userfault+0x58e/0x1900 fs/userfaultfd.c:461 do_anonymous_page mm/memory.c:3099 [inline] handle_pte_fault mm/memory.c:3953 [inline] __handle_mm_fault+0x363e/0x3f20 mm/memory.c:4079 handle_mm_fault+0x1b5/0x6b0 mm/memory.c:4116 do_user_addr_fault arch/x86/mm/fault.c:1444 [inline] __do_page_fault+0x536/0xdd0 arch/x86/mm/fault.c:1510 do_page_fault+0x71/0x5e1 arch/x86/mm/fault.c:1541 page_fault+0x1e/0x30 arch/x86/entry/entry_64.S:1161 } ... key at: [] __key.46572+0x0/0x40 ... acquired at: lock_acquire+0x190/0x410 kernel/locking/lockdep.c:4413 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock+0x2f/0x40 kernel/locking/spinlock.c:151 spin_lock include/linux/spinlock.h:338 [inline] userfaultfd_ctx_read fs/userfaultfd.c:1045 [inline] userfaultfd_read+0x54d/0x1940 fs/userfaultfd.c:1203 __vfs_read+0x8a/0x110 fs/read_write.c:425 vfs_read+0x1f0/0x440 fs/read_write.c:461 ksys_read+0x14f/0x290 fs/read_write.c:587 __do_sys_read fs/read_write.c:597 [inline] __se_sys_read fs/read_write.c:595 [inline] __x64_sys_read+0x73/0xb0 fs/read_write.c:595 do_syscall_64+0xfd/0x6a0 arch/x86/entry/common.c:296 entry_SYSCALL_64_after_hwframe+0x49/0xbe stack backtrace: CPU: 1 PID: 24310 Comm: syz-executor.2 Not tainted 5.2.0-rc7-next-20190703 #28 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+0x172/0x1f0 lib/dump_stack.c:113 print_bad_irq_dependency kernel/locking/lockdep.c:2025 [inline] check_irq_usage.cold+0x5b4/0x72e kernel/locking/lockdep.c:2223 check_prev_add kernel/locking/lockdep.c:2409 [inline] check_prevs_add kernel/locking/lockdep.c:2507 [inline] validate_chain kernel/locking/lockdep.c:2897 [inline] __lock_acquire+0x25bd/0x4c20 kernel/locking/lockdep.c:3880 lock_acquire+0x190/0x410 kernel/locking/lockdep.c:4413 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock+0x2f/0x40 kernel/locking/spinlock.c:151 spin_lock include/linux/spinlock.h:338 [inline] userfaultfd_ctx_read fs/userfaultfd.c:1045 [inline] userfaultfd_read+0x54d/0x1940 fs/userfaultfd.c:1203 __vfs_read+0x8a/0x110 fs/read_write.c:425 vfs_read+0x1f0/0x440 fs/read_write.c:461 ksys_read+0x14f/0x290 fs/read_write.c:587 __do_sys_read fs/read_write.c:597 [inline] __se_sys_read fs/read_write.c:595 [inline] __x64_sys_read+0x73/0xb0 fs/read_write.c:595 do_syscall_64+0xfd/0x6a0 arch/x86/entry/common.c:296 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x4597c9 Code: fd b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007fcdb47cec78 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00000000004597c9 RDX: 0000000000000064 RSI: 0000000020009f9c RDI: 0000000000000006 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007fcdb47cf6d4 R13: 00000000004c58fc R14: 00000000004dba38 R15: 00000000ffffffff