====================================================== WARNING: possible circular locking dependency detected 4.14.150+ #0 Not tainted ------------------------------------------------------ syz-executor.4/6517 is trying to acquire lock: (&mm->mmap_sem){++++}, at: [<00000000dd8d369d>] __might_fault+0xd4/0x1b0 mm/memory.c:4583 but task is already holding lock: (&cpuctx_mutex){+.+.}, at: [<00000000f6276d42>] 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: -> #5 (&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+0x583/0x890 init/main.c:645 secondary_startup_64+0xa5/0xb0 arch/x86/kernel/head_64.S:240 -> #4 (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:1091 kernel_init+0xd/0x164 init/main.c:1023 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:404 -> #3 (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 -> #2 (&sb->s_type->i_mutex_key#10){+.+.}: down_write+0x34/0x90 kernel/locking/rwsem.c:54 inode_lock include/linux/fs.h:724 [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 -> #1 (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:1803 [inline] mmap_region+0x7d9/0xfb0 mm/mmap.c:1736 do_mmap+0x548/0xb80 mm/mmap.c:1512 do_mmap_pgoff include/linux/mm.h:2220 [inline] vm_mmap_pgoff+0x177/0x1c0 mm/util.c:333 SYSC_mmap_pgoff mm/mmap.c:1564 [inline] SyS_mmap_pgoff+0xf4/0x1b0 mm/mmap.c:1520 do_syscall_64+0x19b/0x520 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 -> #0 (&mm->mmap_sem){++++}: lock_acquire+0x12b/0x360 kernel/locking/lockdep.c:3994 __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] perf_read_group kernel/events/core.c:4556 [inline] __perf_read kernel/events/core.c:4623 [inline] perf_read+0x603/0x7f0 kernel/events/core.c:4638 __vfs_read+0xf9/0x590 fs/read_write.c:411 vfs_read+0x131/0x330 fs/read_write.c:447 SYSC_read fs/read_write.c:578 [inline] SyS_read+0x102/0x250 fs/read_write.c:571 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: &mm->mmap_sem --> pmus_lock --> &cpuctx_mutex Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&cpuctx_mutex); lock(pmus_lock); lock(&cpuctx_mutex); lock(&mm->mmap_sem); *** DEADLOCK *** 1 lock held by syz-executor.4/6517: #0: (&cpuctx_mutex){+.+.}, at: [<00000000f6276d42>] perf_event_ctx_lock_nested+0x15a/0x2d0 kernel/events/core.c:1240 stack backtrace: CPU: 0 PID: 6517 Comm: syz-executor.4 Not tainted 4.14.150+ #0 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:3994 __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] perf_read_group kernel/events/core.c:4556 [inline] __perf_read kernel/events/core.c:4623 [inline] perf_read+0x603/0x7f0 kernel/events/core.c:4638 __vfs_read+0xf9/0x590 fs/read_write.c:411 vfs_read+0x131/0x330 fs/read_write.c:447 SYSC_read fs/read_write.c:578 [inline] SyS_read+0x102/0x250 fs/read_write.c:571 do_syscall_64+0x19b/0x520 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x459a59 RSP: 002b:00007fa7e4ebec78 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000459a59 RDX: 0000000000000275 RSI: 0000000020367fe4 RDI: 000000000000000a RBP: 000000000075bfc8 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007fa7e4ebf6d4 R13: 00000000004c5f51 R14: 00000000004dca58 R15: 00000000ffffffff