Messages in this thread | | | From | Dmitry Vyukov <> | Date | Fri, 20 Jan 2017 14:07:55 +0100 | Subject | namespace: deadlock in dec_pid_namespaces |
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Hello,
I've got the following deadlock report while running syzkaller fuzzer on eec0d3d065bfcdf9cd5f56dd2a36b94d12d32297 of linux-next (on odroid device if it matters):
================================= [ INFO: inconsistent lock state ] 4.10.0-rc3-next-20170112-xc2-dirty #6 Not tainted --------------------------------- inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage. swapper/2/0 [HC0[0]:SC1[1]:HE1:SE0] takes: (ucounts_lock){+.?...}, at: [< inline >] spin_lock ./include/linux/spinlock.h:302 (ucounts_lock){+.?...}, at: [<ffff2000081678c8>] put_ucounts+0x60/0x138 kernel/ucount.c:162 {SOFTIRQ-ON-W} state was registered at: [<ffff2000081c82d8>] mark_lock+0x220/0xb60 kernel/locking/lockdep.c:3054 [< inline >] mark_irqflags kernel/locking/lockdep.c:2941 [<ffff2000081c97a8>] __lock_acquire+0x388/0x3260 kernel/locking/lockdep.c:3295 [<ffff2000081cce24>] lock_acquire+0xa4/0x138 kernel/locking/lockdep.c:3753 [< inline >] __raw_spin_lock ./include/linux/spinlock_api_smp.h:144 [<ffff200009798128>] _raw_spin_lock+0x90/0xd0 kernel/locking/spinlock.c:151 [< inline >] spin_lock ./include/linux/spinlock.h:302 [< inline >] get_ucounts kernel/ucount.c:131 [<ffff200008167c28>] inc_ucount+0x80/0x6c8 kernel/ucount.c:189 [< inline >] inc_mnt_namespaces fs/namespace.c:2818 [<ffff200008481850>] alloc_mnt_ns+0x78/0x3a8 fs/namespace.c:2849 [<ffff200008487298>] create_mnt_ns+0x28/0x200 fs/namespace.c:2959 [< inline >] init_mount_tree fs/namespace.c:3199 [<ffff200009bd6674>] mnt_init+0x258/0x384 fs/namespace.c:3251 [<ffff200009bd60bc>] vfs_caches_init+0x6c/0x80 fs/dcache.c:3626 [<ffff200009bb1114>] start_kernel+0x414/0x460 init/main.c:648 [<ffff200009bb01e8>] __primary_switched+0x6c/0x70 arch/arm64/kernel/head.S:456 irq event stamp: 2316924 hardirqs last enabled at (2316924): [< inline >] rcu_do_batch kernel/rcu/tree.c:2911 hardirqs last enabled at (2316924): [< inline >] invoke_rcu_callbacks kernel/rcu/tree.c:3182 hardirqs last enabled at (2316924): [< inline >] __rcu_process_callbacks kernel/rcu/tree.c:3149 hardirqs last enabled at (2316924): [<ffff200008210414>] rcu_process_callbacks+0x7a4/0xc28 kernel/rcu/tree.c:3166 hardirqs last disabled at (2316923): [< inline >] rcu_do_batch kernel/rcu/tree.c:2900 hardirqs last disabled at (2316923): [< inline >] invoke_rcu_callbacks kernel/rcu/tree.c:3182 hardirqs last disabled at (2316923): [< inline >] __rcu_process_callbacks kernel/rcu/tree.c:3149 hardirqs last disabled at (2316923): [<ffff20000820fe80>] rcu_process_callbacks+0x210/0xc28 kernel/rcu/tree.c:3166 softirqs last enabled at (2316912): [<ffff20000811b4c4>] _local_bh_enable+0x4c/0x80 kernel/softirq.c:155 softirqs last disabled at (2316913): [< inline >] do_softirq_own_stack ./include/linux/interrupt.h:488 softirqs last disabled at (2316913): [< inline >] invoke_softirq kernel/softirq.c:371 softirqs last disabled at (2316913): [<ffff20000811c994>] irq_exit+0x264/0x308 kernel/softirq.c:405
other info that might help us debug this: Possible unsafe locking scenario:
CPU0 ---- lock(ucounts_lock); <Interrupt> lock(ucounts_lock);
*** DEADLOCK ***
1 lock held by swapper/2/0: #0: (rcu_callback){......}, at: [< inline >] __rcu_reclaim kernel/rcu/rcu.h:108 #0: (rcu_callback){......}, at: [< inline >] rcu_do_batch kernel/rcu/tree.c:2919 #0: (rcu_callback){......}, at: [< inline >] invoke_rcu_callbacks kernel/rcu/tree.c:3182 #0: (rcu_callback){......}, at: [< inline >] __rcu_process_callbacks kernel/rcu/tree.c:3149 #0: (rcu_callback){......}, at: [<ffff200008210390>] rcu_process_callbacks+0x720/0xc28 kernel/rcu/tree.c:3166
stack backtrace: CPU: 2 PID: 0 Comm: swapper/2 Not tainted 4.10.0-rc3-next-20170112-xc2-dirty #6 Hardware name: Hardkernel ODROID-C2 (DT) Call trace: [<ffff20000808fa60>] dump_backtrace+0x0/0x440 arch/arm64/kernel/traps.c:500 [<ffff20000808fec0>] show_stack+0x20/0x30 arch/arm64/kernel/traps.c:225 [<ffff2000088a99e0>] dump_stack+0x110/0x168 [<ffff2000082fa2b4>] print_usage_bug.part.27+0x49c/0x4bc kernel/locking/lockdep.c:2387 [< inline >] print_usage_bug kernel/locking/lockdep.c:2357 [< inline >] valid_state kernel/locking/lockdep.c:2400 [< inline >] mark_lock_irq kernel/locking/lockdep.c:2617 [<ffff2000081c89ec>] mark_lock+0x934/0xb60 kernel/locking/lockdep.c:3065 [< inline >] mark_irqflags kernel/locking/lockdep.c:2923 [<ffff2000081c9a60>] __lock_acquire+0x640/0x3260 kernel/locking/lockdep.c:3295 [<ffff2000081cce24>] lock_acquire+0xa4/0x138 kernel/locking/lockdep.c:3753 [< inline >] __raw_spin_lock ./include/linux/spinlock_api_smp.h:144 [<ffff200009798128>] _raw_spin_lock+0x90/0xd0 kernel/locking/spinlock.c:151 [< inline >] spin_lock ./include/linux/spinlock.h:302 [<ffff2000081678c8>] put_ucounts+0x60/0x138 kernel/ucount.c:162 [<ffff200008168364>] dec_ucount+0xf4/0x158 kernel/ucount.c:214 [< inline >] dec_pid_namespaces kernel/pid_namespace.c:89 [<ffff200008293dc8>] delayed_free_pidns+0x40/0xe0 kernel/pid_namespace.c:156 [< inline >] __rcu_reclaim kernel/rcu/rcu.h:118 [< inline >] rcu_do_batch kernel/rcu/tree.c:2919 [< inline >] invoke_rcu_callbacks kernel/rcu/tree.c:3182 [< inline >] __rcu_process_callbacks kernel/rcu/tree.c:3149 [<ffff2000082103d8>] rcu_process_callbacks+0x768/0xc28 kernel/rcu/tree.c:3166 [<ffff2000080821dc>] __do_softirq+0x324/0x6e0 kernel/softirq.c:284 [< inline >] do_softirq_own_stack ./include/linux/interrupt.h:488 [< inline >] invoke_softirq kernel/softirq.c:371 [<ffff20000811c994>] irq_exit+0x264/0x308 kernel/softirq.c:405 [<ffff2000081ecc28>] __handle_domain_irq+0xc0/0x150 kernel/irq/irqdesc.c:636 [<ffff200008081c80>] gic_handle_irq+0x68/0xd8 Exception stack(0xffff8000648e7dd0 to 0xffff8000648e7f00) 7dc0: ffff8000648d4b3c 0000000000000007 7de0: 0000000000000000 1ffff0000c91a967 1ffff0000c91a967 1ffff0000c91a967 7e00: ffff20000a4b6b68 0000000000000001 0000000000000007 0000000000000001 7e20: 1fffe4000149ae90 ffff200009d35000 0000000000000000 0000000000000002 7e40: 0000000000000000 0000000000000000 0000000002624a1a 0000000000000000 7e60: 0000000000000000 ffff200009cbcd88 000060006d2ed000 0000000000000140 7e80: ffff200009cff000 ffff200009cb6000 ffff200009cc2020 ffff200009d2159d 7ea0: 0000000000000000 ffff8000648d4380 0000000000000000 ffff8000648e7f00 7ec0: ffff20000820a478 ffff8000648e7f00 ffff20000820a47c 0000000010000145 7ee0: 0000000000000140 dfff200000000000 ffffffffffffffff ffff20000820a478 [<ffff2000080837f8>] el1_irq+0xb8/0x130 arch/arm64/kernel/entry.S:486 [< inline >] arch_local_irq_restore ./arch/arm64/include/asm/irqflags.h:81 [<ffff20000820a47c>] rcu_idle_exit+0x64/0xa8 kernel/rcu/tree.c:1030 [< inline >] cpuidle_idle_call kernel/sched/idle.c:200 [<ffff2000081bcbfc>] do_idle+0x1dc/0x2d0 kernel/sched/idle.c:243 [<ffff2000081bd1cc>] cpu_startup_entry+0x24/0x28 kernel/sched/idle.c:345 [<ffff200008099f8c>] secondary_start_kernel+0x2cc/0x358 arch/arm64/kernel/smp.c:276 [<000000000279f1a4>] 0x279f1a4
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