====================================================== WARNING: possible circular locking dependency detected 4.14.139+ #34 Not tainted ------------------------------------------------------ syz-executor.3/7353 is trying to acquire lock: (&event->child_mutex){+.+.}, at: [<00000000b378cbb6>] perf_event_for_each_child+0x82/0x150 kernel/events/core.c:4687 but task is already holding lock: (&cpuctx_mutex){+.+.}, at: [<000000006e51dfa1>] perf_event_ctx_lock_nested+0x15a/0x2d0 kernel/events/core.c:1240 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #8 (&cpuctx_mutex){+.+.}: __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xf7/0x13e0 kernel/locking/mutex.c:893 perf_event_init_cpu+0xa8/0x150 kernel/events/core.c:11231 perf_event_init+0x289/0x2c5 kernel/events/core.c:11278 start_kernel+0x43d/0x74a init/main.c:621 secondary_startup_64+0xa5/0xb0 arch/x86/kernel/head_64.S:240 -> #7 (pmus_lock){+.+.}: __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xf7/0x13e0 kernel/locking/mutex.c:893 perf_event_init_cpu+0x2c/0x150 kernel/events/core.c:11225 cpuhp_invoke_callback+0x207/0x1a30 kernel/cpu.c:184 cpuhp_up_callbacks kernel/cpu.c:572 [inline] _cpu_up+0x20b/0x500 kernel/cpu.c:1134 do_cpu_up+0x64/0x120 kernel/cpu.c:1169 smp_init+0x142/0x154 kernel/smp.c:578 kernel_init_freeable+0x196/0x3b0 init/main.c:1067 kernel_init+0xd/0x164 init/main.c:999 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:404 -> #6 (cpu_hotplug_lock.rw_sem){++++}: percpu_down_read_preempt_disable include/linux/percpu-rwsem.h:36 [inline] percpu_down_read include/linux/percpu-rwsem.h:59 [inline] cpus_read_lock+0x39/0xc0 kernel/cpu.c:295 get_online_cpus include/linux/cpu.h:140 [inline] lru_add_drain_all+0xa/0x20 mm/swap.c:729 shmem_wait_for_pins mm/shmem.c:2732 [inline] shmem_add_seals+0x633/0x11b0 mm/shmem.c:2841 shmem_fcntl+0xea/0x120 mm/shmem.c:2876 do_fcntl+0x5c8/0xd20 fs/fcntl.c:421 SYSC_fcntl fs/fcntl.c:463 [inline] SyS_fcntl+0xc6/0x100 fs/fcntl.c:448 do_syscall_64+0x19b/0x520 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 -> #5 (&sb->s_type->i_mutex_key#10){+.+.}: down_write+0x34/0x90 kernel/locking/rwsem.c:54 inode_lock include/linux/fs.h:718 [inline] shmem_fallocate+0x150/0xae0 mm/shmem.c:2902 ashmem_shrink_scan drivers/staging/android/ashmem.c:453 [inline] ashmem_shrink_scan+0x1ca/0x4f0 drivers/staging/android/ashmem.c:437 ashmem_ioctl+0x2b4/0xd20 drivers/staging/android/ashmem.c:795 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:500 [inline] do_vfs_ioctl+0xabe/0x1040 fs/ioctl.c:684 SYSC_ioctl fs/ioctl.c:701 [inline] SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692 do_syscall_64+0x19b/0x520 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 -> #4 (ashmem_mutex){+.+.}: __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xf7/0x13e0 kernel/locking/mutex.c:893 ashmem_mmap+0x4c/0x450 drivers/staging/android/ashmem.c:369 call_mmap include/linux/fs.h:1793 [inline] mmap_region+0x7d9/0xfb0 mm/mmap.c:1732 do_mmap+0x548/0xb80 mm/mmap.c:1510 do_mmap_pgoff include/linux/mm.h:2209 [inline] vm_mmap_pgoff+0x177/0x1c0 mm/util.c:333 SYSC_mmap_pgoff mm/mmap.c:1560 [inline] SyS_mmap_pgoff+0xf4/0x1b0 mm/mmap.c:1518 do_syscall_64+0x19b/0x520 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 -> #3 (&mm->mmap_sem){++++}: __might_fault mm/memory.c:4584 [inline] __might_fault+0x137/0x1b0 mm/memory.c:4569 _copy_to_user+0x27/0xd0 lib/usercopy.c:25 copy_to_user include/linux/uaccess.h:155 [inline] filldir+0x198/0x2f0 fs/readdir.c:197 dir_emit_dot include/linux/fs.h:3379 [inline] dir_emit_dots include/linux/fs.h:3390 [inline] dcache_readdir+0x123/0x5c0 fs/libfs.c:192 iterate_dir+0x1a5/0x5f0 fs/readdir.c:52 SYSC_getdents fs/readdir.c:232 [inline] SyS_getdents+0x145/0x290 fs/readdir.c:213 do_syscall_64+0x19b/0x520 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 -> #2 (&sb->s_type->i_mutex_key#5){++++}: down_write+0x34/0x90 kernel/locking/rwsem.c:54 inode_lock include/linux/fs.h:718 [inline] start_creating.part.0+0x4c/0x150 fs/tracefs/inode.c:335 start_creating fs/tracefs/inode.c:324 [inline] tracefs_create_file+0x74/0x450 fs/tracefs/inode.c:400 create_event_toplevel_files+0x2d/0x150 kernel/trace/trace_events.c:2909 early_event_add_tracer kernel/trace/trace_events.c:2996 [inline] event_trace_init+0x312/0x4ec kernel/trace/trace_events.c:3161 do_one_initcall+0xa0/0x1ac init/main.c:825 do_initcall_level init/main.c:891 [inline] do_initcalls init/main.c:899 [inline] do_basic_setup init/main.c:917 [inline] kernel_init_freeable+0x2ef/0x3b0 init/main.c:1074 kernel_init+0xd/0x164 init/main.c:999 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:404 -> #1 (event_mutex){+.+.}: __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xf7/0x13e0 kernel/locking/mutex.c:893 perf_trace_destroy+0x23/0x100 kernel/trace/trace_event_perf.c:234 _free_event+0x293/0xbb0 kernel/events/core.c:4243 free_event+0x42/0xa0 kernel/events/core.c:4270 perf_event_release_kernel+0x35c/0x880 kernel/events/core.c:4414 perf_release+0x33/0x40 kernel/events/core.c:4440 __fput+0x25e/0x710 fs/file_table.c:210 task_work_run+0x125/0x1a0 kernel/task_work.c:113 exit_task_work include/linux/task_work.h:22 [inline] do_exit+0x9cb/0x2a20 kernel/exit.c:875 do_group_exit+0x100/0x2e0 kernel/exit.c:978 SYSC_exit_group kernel/exit.c:989 [inline] SyS_exit_group+0x19/0x20 kernel/exit.c:987 do_syscall_64+0x19b/0x520 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 -> #0 (&event->child_mutex){+.+.}: lock_acquire+0x12b/0x360 kernel/locking/lockdep.c:3991 __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xf7/0x13e0 kernel/locking/mutex.c:893 perf_event_for_each_child+0x82/0x150 kernel/events/core.c:4687 _perf_ioctl kernel/events/core.c:4871 [inline] perf_ioctl+0x53e/0x1bb0 kernel/events/core.c:4883 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:500 [inline] do_vfs_ioctl+0xabe/0x1040 fs/ioctl.c:684 SYSC_ioctl fs/ioctl.c:701 [inline] SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692 do_syscall_64+0x19b/0x520 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 other info that might help us debug this: Chain exists of: &event->child_mutex --> pmus_lock --> &cpuctx_mutex Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&cpuctx_mutex); lock(pmus_lock); lock(&cpuctx_mutex); lock(&event->child_mutex); *** DEADLOCK *** 1 lock held by syz-executor.3/7353: #0: (&cpuctx_mutex){+.+.}, at: [<000000006e51dfa1>] perf_event_ctx_lock_nested+0x15a/0x2d0 kernel/events/core.c:1240 stack backtrace: CPU: 1 PID: 7353 Comm: syz-executor.3 Not tainted 4.14.139+ #34 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0xca/0x134 lib/dump_stack.c:53 print_circular_bug.isra.0.cold+0x2dc/0x425 kernel/locking/lockdep.c:1258 check_prev_add kernel/locking/lockdep.c:1901 [inline] check_prevs_add kernel/locking/lockdep.c:2018 [inline] validate_chain kernel/locking/lockdep.c:2460 [inline] __lock_acquire+0x2f5f/0x4320 kernel/locking/lockdep.c:3487 lock_acquire+0x12b/0x360 kernel/locking/lockdep.c:3991 __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xf7/0x13e0 kernel/locking/mutex.c:893 perf_event_for_each_child+0x82/0x150 kernel/events/core.c:4687 _perf_ioctl kernel/events/core.c:4871 [inline] perf_ioctl+0x53e/0x1bb0 kernel/events/core.c:4883 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:500 [inline] do_vfs_ioctl+0xabe/0x1040 fs/ioctl.c:684 SYSC_ioctl fs/ioctl.c:701 [inline] SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692 do_syscall_64+0x19b/0x520 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x459829 RSP: 002b:00007fe6bdbf5c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000459829 RDX: 0000000000000000 RSI: 0000000000002403 RDI: 0000000000000004 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007fe6bdbf66d4 R13: 00000000004c324a R14: 00000000004d69c0 R15: 00000000ffffffff kauditd_printk_skb: 45 callbacks suppressed audit: type=1400 audit(1566072969.041:90152): avc: denied { map } for pid=7391 comm="syz-executor.4" path="/root/syzkaller-testdir812875195/syzkaller.q5LNvq/758/bus" dev="sda1" ino=16771 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:object_r:user_home_t:s0 tclass=file permissive=1 audit: type=1400 audit(1566072969.481:90153): avc: denied { map } for pid=7418 comm="syz-executor.4" path="/root/syzkaller-testdir812875195/syzkaller.q5LNvq/759/bus" dev="sda1" ino=16806 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:object_r:user_home_t:s0 tclass=file permissive=1 audit: type=1400 audit(1566072969.861:90154): avc: denied { map } for pid=7434 comm="syz-executor.4" path="/dev/loop0" dev="sda1" ino=2661 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=system_u:object_r:file_t:s0 tclass=blk_file permissive=1 audit: type=1400 audit(1566072970.201:90155): avc: denied { map } for pid=7454 comm="modprobe" path="/bin/kmod" dev="sda1" ino=1440 scontext=system_u:system_r:kernel_t:s0 tcontext=system_u:object_r:file_t:s0 tclass=file permissive=1 audit: type=1400 audit(1566072970.201:90156): avc: denied { map } for pid=7454 comm="modprobe" path="/bin/kmod" dev="sda1" ino=1440 scontext=system_u:system_r:kernel_t:s0 tcontext=system_u:object_r:file_t:s0 tclass=file permissive=1 audit: type=1400 audit(1566072970.201:90157): avc: denied { map } for pid=7454 comm="modprobe" path="/lib/x86_64-linux-gnu/ld-2.13.so" dev="sda1" ino=2668 scontext=system_u:system_r:kernel_t:s0 tcontext=system_u:object_r:file_t:s0 tclass=file permissive=1 audit: type=1400 audit(1566072970.201:90158): avc: denied { map } for pid=7454 comm="modprobe" path="/lib/x86_64-linux-gnu/ld-2.13.so" dev="sda1" ino=2668 scontext=system_u:system_r:kernel_t:s0 tcontext=system_u:object_r:file_t:s0 tclass=file permissive=1 audit: type=1400 audit(1566072970.211:90159): avc: denied { map } for pid=7454 comm="modprobe" path="/etc/ld.so.cache" dev="sda1" ino=2503 scontext=system_u:system_r:kernel_t:s0 tcontext=system_u:object_r:file_t:s0 tclass=file permissive=1 audit: type=1400 audit(1566072970.211:90160): avc: denied { map } for pid=7454 comm="modprobe" path="/lib/x86_64-linux-gnu/libkmod.so.2.1.3" dev="sda1" ino=2811 scontext=system_u:system_r:kernel_t:s0 tcontext=system_u:object_r:file_t:s0 tclass=file permissive=1 audit: type=1400 audit(1566072970.211:90161): avc: denied { map } for pid=7454 comm="modprobe" path="/lib/x86_64-linux-gnu/libkmod.so.2.1.3" dev="sda1" ino=2811 scontext=system_u:system_r:kernel_t:s0 tcontext=system_u:object_r:file_t:s0 tclass=file permissive=1