====================================================== WARNING: possible circular locking dependency detected 4.14.91+ #3 Not tainted ------------------------------------------------------ syz-executor0/14871 is trying to acquire lock: (&mm->mmap_sem){++++}, at: [] __might_fault+0xd4/0x1b0 mm/memory.c:4554 but task is already holding lock: (&cpuctx_mutex){+.+.}, at: [] perf_event_ctx_lock_nested+0x14d/0x2c0 kernel/events/core.c:1240 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #5 (&cpuctx_mutex){+.+.}: -> #4 (pmus_lock){+.+.}: -> #3 (cpu_hotplug_lock.rw_sem){++++}: -> #2 (&sb->s_type->i_mutex_key#10){+.+.}: -> #1 (ashmem_mutex){+.+.}: -> #0 (&mm->mmap_sem){++++}: 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-executor0/14871: #0: (&cpuctx_mutex){+.+.}, at: [] perf_event_ctx_lock_nested+0x14d/0x2c0 kernel/events/core.c:1240 stack backtrace: CPU: 0 PID: 14871 Comm: syz-executor0 Not tainted 4.14.91+ #3 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0xb9/0x10e lib/dump_stack.c:53 print_circular_bug.isra.0.cold+0x2dc/0x425 kernel/locking/lockdep.c:1258 SELinux: unrecognized netlink message: protocol=0 nlmsg_type=47764 sclass=netlink_route_socket pig=15628 comm=syz-executor0 SELinux: unrecognized netlink message: protocol=0 nlmsg_type=47764 sclass=netlink_route_socket pig=15638 comm=syz-executor0 audit: type=1400 audit(2000000199.239:133): avc: denied { map } for pid=15702 comm="syz-executor3" path="socket:[41412]" dev="sockfs" ino=41412 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=netlink_route_socket permissive=1 SELinux: unrecognized netlink message: protocol=0 nlmsg_type=0 sclass=netlink_route_socket pig=15750 comm=syz-executor3 SELinux: unrecognized netlink message: protocol=0 nlmsg_type=0 sclass=netlink_route_socket pig=15771 comm=syz-executor3 SELinux: unrecognized netlink message: protocol=0 nlmsg_type=28005 sclass=netlink_route_socket pig=15819 comm=syz-executor1 SELinux: unrecognized netlink message: protocol=0 nlmsg_type=0 sclass=netlink_route_socket pig=15946 comm=syz-executor4 SELinux: unrecognized netlink message: protocol=0 nlmsg_type=373 sclass=netlink_route_socket pig=15957 comm=syz-executor0 SELinux: unrecognized netlink message: protocol=0 nlmsg_type=0 sclass=netlink_route_socket pig=15970 comm=syz-executor4 SELinux: unrecognized netlink message: protocol=0 nlmsg_type=373 sclass=netlink_route_socket pig=15957 comm=syz-executor0 SELinux: unrecognized netlink message: protocol=0 nlmsg_type=26159 sclass=netlink_route_socket pig=16158 comm=syz-executor4