loop0: detected capacity change from 0 to 1024
EXT4-fs (loop0): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: none.
FAULT_INJECTION: forcing a failure.
name failslab, interval 1, probability 0, space 0, times 1
CPU: 0 UID: 0 PID: 5335 Comm: syz.0.0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 fail_dump lib/fault-inject.c:73 [inline]
 should_fail_ex+0x412/0x560 lib/fault-inject.c:174
 should_failslab+0xa8/0x100 mm/failslab.c:46
 slab_pre_alloc_hook mm/slub.c:4522 [inline]
 slab_alloc_node mm/slub.c:4875 [inline]
 __kmalloc_cache_noprof+0x88/0x660 mm/slub.c:5410
 kmalloc_noprof include/linux/slab.h:950 [inline]
 pfnmap_track_ctx_alloc mm/memory.c:3066 [inline]
 remap_pfn_range_track mm/memory.c:3106 [inline]
 do_remap_pfn_range+0x103e/0x1250 mm/memory.c:3126
 map_range+0x199/0x230 kernel/events/core.c:7206
 perf_mmap+0x3ff/0x490 kernel/events/core.c:7482
 vfs_mmap include/linux/fs.h:2074 [inline]
 mmap_file mm/internal.h:168 [inline]
 __mmap_new_file_vma mm/vma.c:2496 [inline]
 __mmap_new_vma mm/vma.c:2562 [inline]
 __mmap_region mm/vma.c:2771 [inline]
 mmap_region+0x1ab2/0x2280 mm/vma.c:2856
 do_mmap+0xc39/0x10c0 mm/mmap.c:560
 vm_mmap_pgoff+0x2c9/0x4f0 mm/util.c:581
 ksys_mmap_pgoff+0x51e/0x760 mm/mmap.c:606
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f1cedf9c819
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 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 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f1ceeea9fe8 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007f1cee215fa0 RCX: 00007f1cedf9c819
RDX: 0000000000000000 RSI: 0000000000001000 RDI: 0000200000ffd000
RBP: 00007f1ceeeaa050 R08: 0000000000000003 R09: 0000000000000000
R10: 0000000000000011 R11: 0000000000000246 R12: 0000000000000002
R13: 00007f1cee216038 R14: 00007f1cee215fa0 R15: 00007ffce4dedb88
 </TASK>
============================================
WARNING: possible recursive locking detected
syzkaller #0 Not tainted
--------------------------------------------
syz.0.0/5335 is trying to acquire lock:
ffff8880129889c0 (&event->mmap_mutex){+.+.}-{4:4}, at: refcount_dec_and_mutex_lock+0x30/0xa0 lib/refcount.c:118

but task is already holding lock:
ffff8880129889c0 (&event->mmap_mutex){+.+.}-{4:4}, at: class_mutex_constructor include/linux/mutex.h:253 [inline]
ffff8880129889c0 (&event->mmap_mutex){+.+.}-{4:4}, at: perf_mmap+0x1bb/0x490 kernel/events/core.c:7449

other info that might help us debug this:
 Possible unsafe locking scenario:

       CPU0
       ----
  lock(&event->mmap_mutex);
  lock(&event->mmap_mutex);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

2 locks held by syz.0.0/5335:
 #0: ffff888012b927f8 (&mm->mmap_lock){++++}-{4:4}, at: mmap_write_lock_killable include/linux/mmap_lock.h:554 [inline]
 #0: ffff888012b927f8 (&mm->mmap_lock){++++}-{4:4}, at: vm_mmap_pgoff+0x234/0x4f0 mm/util.c:579
 #1: ffff8880129889c0 (&event->mmap_mutex){+.+.}-{4:4}, at: class_mutex_constructor include/linux/mutex.h:253 [inline]
 #1: ffff8880129889c0 (&event->mmap_mutex){+.+.}-{4:4}, at: perf_mmap+0x1bb/0x490 kernel/events/core.c:7449

stack backtrace:
CPU: 0 UID: 0 PID: 5335 Comm: syz.0.0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_deadlock_bug+0x279/0x290 kernel/locking/lockdep.c:3041
 check_deadlock kernel/locking/lockdep.c:3093 [inline]
 validate_chain kernel/locking/lockdep.c:3895 [inline]
 __lock_acquire+0x253f/0x2cf0 kernel/locking/lockdep.c:5237
 lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868
 __mutex_lock_common kernel/locking/mutex.c:632 [inline]
 __mutex_lock+0x1a3/0x1550 kernel/locking/mutex.c:806
 refcount_dec_and_mutex_lock+0x30/0xa0 lib/refcount.c:118
 perf_mmap_close+0x953/0xf90 kernel/events/core.c:7060
 perf_mmap+0x41b/0x490 kernel/events/core.c:7484
 vfs_mmap include/linux/fs.h:2074 [inline]
 mmap_file mm/internal.h:168 [inline]
 __mmap_new_file_vma mm/vma.c:2496 [inline]
 __mmap_new_vma mm/vma.c:2562 [inline]
 __mmap_region mm/vma.c:2771 [inline]
 mmap_region+0x1ab2/0x2280 mm/vma.c:2856
 do_mmap+0xc39/0x10c0 mm/mmap.c:560
 vm_mmap_pgoff+0x2c9/0x4f0 mm/util.c:581
 ksys_mmap_pgoff+0x51e/0x760 mm/mmap.c:606
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f1cedf9c819
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 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 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f1ceeea9fe8 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007f1cee215fa0 RCX: 00007f1cedf9c819
RDX: 0000000000000000 RSI: 0000000000001000 RDI: 0000200000ffd000
RBP: 00007f1ceeeaa050 R08: 0000000000000003 R09: 0000000000000000
R10: 0000000000000011 R11: 0000000000000246 R12: 0000000000000002
R13: 00007f1cee216038 R14: 00007f1cee215fa0 R15: 00007ffce4dedb88
 </TASK>