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SubjectRe: [syzbot] possible deadlock in vm_mmap_pgoff
From
syzbot has found a reproducer for the following issue on:

HEAD commit: 9bead1b58c4c Merge tag 'array-bounds-fixes-5.14-rc3' of gi..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=155a1f5c300000
kernel config: https://syzkaller.appspot.com/x/.config?x=5dc0e3202ae2f574
dashboard link: https://syzkaller.appspot.com/bug?extid=f619f7c0a2a5f87694e6
compiler: Debian clang version 11.0.1-2, GNU ld (GNU Binutils for Debian) 2.35.1
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=14e2e196300000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11cc4846300000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f619f7c0a2a5f87694e6@syzkaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
5.14.0-rc2-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor238/8449 is trying to acquire lock:
ffffffff8c7658e8 (event_mutex){+.+.}-{3:3}, at: perf_trace_destroy+0x27/0xb0 kernel/trace/trace_event_perf.c:241

but task is already holding lock:
ffff888033788f28 (&mm->mmap_lock#2){++++}-{3:3}, at: mmap_write_lock_killable include/linux/mmap_lock.h:87 [inline]
ffff888033788f28 (&mm->mmap_lock#2){++++}-{3:3}, at: vm_mmap_pgoff+0x14d/0x2b0 mm/util.c:517

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (&mm->mmap_lock#2){++++}-{3:3}:
lock_acquire+0x182/0x4a0 kernel/locking/lockdep.c:5625
down_write_killable+0xaa/0x1b0 kernel/locking/rwsem.c:1417
mmap_write_lock_killable include/linux/mmap_lock.h:87 [inline]
dup_mmap+0xde/0xed0 kernel/fork.c:484
dup_mm+0x8c/0x310 kernel/fork.c:1379
copy_mm kernel/fork.c:1431 [inline]
copy_process+0x22e8/0x5b00 kernel/fork.c:2119
kernel_clone+0x21a/0x7d0 kernel/fork.c:2509
__do_sys_clone kernel/fork.c:2626 [inline]
__se_sys_clone kernel/fork.c:2610 [inline]
__x64_sys_clone+0x236/0x2b0 kernel/fork.c:2610
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae

-> #2 (dup_mmap_sem){++++}-{0:0}:
lock_acquire+0x182/0x4a0 kernel/locking/lockdep.c:5625
percpu_down_write+0x52/0x2f0 kernel/locking/percpu-rwsem.c:217
register_for_each_vma+0x32/0xc20 kernel/events/uprobes.c:1041
__uprobe_register+0x5d4/0x860 kernel/events/uprobes.c:1182
trace_uprobe_enable kernel/trace/trace_uprobe.c:1065 [inline]
probe_event_enable+0x399/0xbd0 kernel/trace/trace_uprobe.c:1134
perf_trace_event_reg kernel/trace/trace_event_perf.c:129 [inline]
perf_trace_event_init+0x49b/0x950 kernel/trace/trace_event_perf.c:204
perf_uprobe_init+0x138/0x1a0 kernel/trace/trace_event_perf.c:336
perf_uprobe_event_init+0xfe/0x180 kernel/events/core.c:9875
perf_try_init_event+0x13e/0x3d0 kernel/events/core.c:11192
perf_init_event kernel/events/core.c:11256 [inline]
perf_event_alloc+0x1155/0x2c10 kernel/events/core.c:11547
__do_sys_perf_event_open kernel/events/core.c:12037 [inline]
__se_sys_perf_event_open+0x7a6/0x4020 kernel/events/core.c:11929
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae

-> #1 (&uprobe->register_rwsem){+.+.}-{3:3}:
lock_acquire+0x182/0x4a0 kernel/locking/lockdep.c:5625
down_write+0x97/0x170 kernel/locking/rwsem.c:1406
__uprobe_register+0x4fd/0x860 kernel/events/uprobes.c:1178
trace_uprobe_enable kernel/trace/trace_uprobe.c:1065 [inline]
probe_event_enable+0x399/0xbd0 kernel/trace/trace_uprobe.c:1134
perf_trace_event_reg kernel/trace/trace_event_perf.c:129 [inline]
perf_trace_event_init+0x49b/0x950 kernel/trace/trace_event_perf.c:204
perf_uprobe_init+0x138/0x1a0 kernel/trace/trace_event_perf.c:336
perf_uprobe_event_init+0xfe/0x180 kernel/events/core.c:9875
perf_try_init_event+0x13e/0x3d0 kernel/events/core.c:11192
perf_init_event kernel/events/core.c:11256 [inline]
perf_event_alloc+0x1155/0x2c10 kernel/events/core.c:11547
__do_sys_perf_event_open kernel/events/core.c:12037 [inline]
__se_sys_perf_event_open+0x7a6/0x4020 kernel/events/core.c:11929
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae

-> #0 (event_mutex){+.+.}-{3:3}:
check_prev_add kernel/locking/lockdep.c:3051 [inline]
check_prevs_add+0x4f9/0x5b30 kernel/locking/lockdep.c:3174
validate_chain kernel/locking/lockdep.c:3789 [inline]
__lock_acquire+0x4476/0x6100 kernel/locking/lockdep.c:5015
lock_acquire+0x182/0x4a0 kernel/locking/lockdep.c:5625
__mutex_lock_common+0x1ad/0x3770 kernel/locking/mutex.c:959
__mutex_lock kernel/locking/mutex.c:1104 [inline]
mutex_lock_nested+0x1a/0x20 kernel/locking/mutex.c:1119
perf_trace_destroy+0x27/0xb0 kernel/trace/trace_event_perf.c:241
_free_event+0xd4d/0x12f0 kernel/events/core.c:4959
put_event kernel/events/core.c:5053 [inline]
perf_mmap_close+0x8ed/0xdf0 kernel/events/core.c:6098
remove_vma mm/mmap.c:186 [inline]
remove_vma_list mm/mmap.c:2656 [inline]
__do_munmap+0x1b95/0x2050 mm/mmap.c:2914
do_munmap mm/mmap.c:2922 [inline]
munmap_vma_range mm/mmap.c:604 [inline]
mmap_region+0x90c/0x1df0 mm/mmap.c:1753
do_mmap+0x89e/0x10c0 mm/mmap.c:1584
vm_mmap_pgoff+0x19e/0x2b0 mm/util.c:519
ksys_mmap_pgoff+0x504/0x7b0 mm/mmap.c:1635
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae

other info that might help us debug this:

Chain exists of:
event_mutex --> dup_mmap_sem --> &mm->mmap_lock#2

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(&mm->mmap_lock#2);
lock(dup_mmap_sem);
lock(&mm->mmap_lock#2);
lock(event_mutex);

*** DEADLOCK ***

1 lock held by syz-executor238/8449:
#0: ffff888033788f28 (&mm->mmap_lock#2){++++}-{3:3}, at: mmap_write_lock_killable include/linux/mmap_lock.h:87 [inline]
#0: ffff888033788f28 (&mm->mmap_lock#2){++++}-{3:3}, at: vm_mmap_pgoff+0x14d/0x2b0 mm/util.c:517

stack backtrace:
CPU: 1 PID: 8449 Comm: syz-executor238 Not tainted 5.14.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x1ae/0x29f lib/dump_stack.c:105
print_circular_bug+0xb17/0xdc0 kernel/locking/lockdep.c:2009
check_noncircular+0x2cc/0x390 kernel/locking/lockdep.c:2131
check_prev_add kernel/locking/lockdep.c:3051 [inline]
check_prevs_add+0x4f9/0x5b30 kernel/locking/lockdep.c:3174
validate_chain kernel/locking/lockdep.c:3789 [inline]
__lock_acquire+0x4476/0x6100 kernel/locking/lockdep.c:5015
lock_acquire+0x182/0x4a0 kernel/locking/lockdep.c:5625
__mutex_lock_common+0x1ad/0x3770 kernel/locking/mutex.c:959
__mutex_lock kernel/locking/mutex.c:1104 [inline]
mutex_lock_nested+0x1a/0x20 kernel/locking/mutex.c:1119
perf_trace_destroy+0x27/0xb0 kernel/trace/trace_event_perf.c:241
_free_event+0xd4d/0x12f0 kernel/events/core.c:4959
put_event kernel/events/core.c:5053 [inline]
perf_mmap_close+0x8ed/0xdf0 kernel/events/core.c:6098
remove_vma mm/mmap.c:186 [inline]
remove_vma_list mm/mmap.c:2656 [inline]
__do_munmap+0x1b95/0x2050 mm/mmap.c:2914
do_munmap mm/mmap.c:2922 [inline]
munmap_vma_range mm/mmap.c:604 [inline]
mmap_region+0x90c/0x1df0 mm/mmap.c:1753
do_mmap+0x89e/0x10c0 mm/mmap.c:1584
vm_mmap_pgoff+0x19e/0x2b0 mm/util.c:519
ksys_mmap_pgoff+0x504/0x7b0 mm/mmap.c:1635
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x44e009
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 91 18 00 00 90 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fefce402308 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00000000004cc4e8 RCX: 000000000044e009
RDX: 0000000000000000 RSI: 0000000000003000 RDI: 0000000020ffc000
RBP: 00000000004cc4e0 R08: 00

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