possible deadlock in proc_tgid_io_accounting (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 3f8a27f9e27b Linux 4.19.211
git tree: linux-4.19.y
console output: https://syzkaller.appspot.com/x/log.txt?x=14d4f18cc80000
kernel config: https://syzkaller.appspot.com/x/.config?x=9b9277b418617afe
dashboard link: https://syzkaller.appspot.com/bug?extid=130dee290a43d16fa711
compiler: gcc version 10.2.1 20210110 (Debian 10.2.1-6)

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/98c0bdb4abb3/disk-3f8a27f9.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/ea228ff02669/vmlinux-3f8a27f9.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+130dee...@syzkaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
4.19.211-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.5/14535 is trying to acquire lock:
00000000b42c8c20 (&sig->cred_guard_mutex){+.+.}, at: do_io_accounting fs/proc/base.c:2750 [inline]
00000000b42c8c20 (&sig->cred_guard_mutex){+.+.}, at: proc_tgid_io_accounting+0x1cf/0x7f0 fs/proc/base.c:2799

but task is already holding lock:
00000000e07b062c (&p->lock){+.+.}, at: seq_read+0x6b/0x11c0 fs/seq_file.c:164

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (&p->lock){+.+.}:
cgroup: cgroup2: unknown option "memory_recursiveprot"
seq_read+0x6b/0x11c0 fs/seq_file.c:164
proc_reg_read+0x1bd/0x2d0 fs/proc/inode.c:231
do_loop_readv_writev fs/read_write.c:701 [inline]
do_loop_readv_writev fs/read_write.c:688 [inline]
do_iter_read+0x471/0x630 fs/read_write.c:925
vfs_readv+0xe5/0x150 fs/read_write.c:987
kernel_readv fs/splice.c:362 [inline]
default_file_splice_read+0x457/0xa00 fs/splice.c:417
do_splice_to+0x10e/0x160 fs/splice.c:881
splice_direct_to_actor+0x2b9/0x8d0 fs/splice.c:959
do_splice_direct+0x1a7/0x270 fs/splice.c:1068
do_sendfile+0x550/0xc30 fs/read_write.c:1447
__do_sys_sendfile64 fs/read_write.c:1502 [inline]
__se_sys_sendfile64+0xc4/0x160 fs/read_write.c:1494
IPVS: ftp: loaded support on port[0] = 21
do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe

-> #2 (sb_writers#3){.+.+}:
sb_start_write include/linux/fs.h:1579 [inline]
mnt_want_write+0x3a/0xb0 fs/namespace.c:360
ovl_do_remove+0xf0/0xdb0 fs/overlayfs/dir.c:845
vfs_rmdir.part.0+0x10f/0x3d0 fs/namei.c:3882
vfs_rmdir fs/namei.c:3868 [inline]
do_rmdir+0x3fd/0x490 fs/namei.c:3943
do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe

-> #1 (&ovl_i_mutex_dir_key[depth]){++++}:
inode_lock_shared include/linux/fs.h:758 [inline]
lookup_slow fs/namei.c:1688 [inline]
walk_component+0x798/0xda0 fs/namei.c:1811
lookup_last fs/namei.c:2274 [inline]
path_lookupat+0x1ff/0x8d0 fs/namei.c:2319
filename_lookup+0x1ac/0x5a0 fs/namei.c:2349
create_local_trace_uprobe+0x82/0x490 kernel/trace/trace_uprobe.c:1356
perf_uprobe_init+0x128/0x200 kernel/trace/trace_event_perf.c:317
perf_uprobe_event_init+0xf8/0x190 kernel/events/core.c:8613
perf_try_init_event+0x124/0x2e0 kernel/events/core.c:9884
perf_init_event kernel/events/core.c:9915 [inline]
perf_event_alloc.part.0+0x1b16/0x2eb0 kernel/events/core.c:10189
perf_event_alloc kernel/events/core.c:10559 [inline]
__do_sys_perf_event_open kernel/events/core.c:10660 [inline]
__se_sys_perf_event_open+0x550/0x2720 kernel/events/core.c:10549
do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe

-> #0 (&sig->cred_guard_mutex){+.+.}:
__mutex_lock_common kernel/locking/mutex.c:937 [inline]
__mutex_lock+0xd7/0x1190 kernel/locking/mutex.c:1078
do_io_accounting fs/proc/base.c:2750 [inline]
proc_tgid_io_accounting+0x1cf/0x7f0 fs/proc/base.c:2799
proc_single_show+0xeb/0x170 fs/proc/base.c:755
seq_read+0x4e0/0x11c0 fs/seq_file.c:232
__vfs_read+0xf7/0x750 fs/read_write.c:416
cgroup: cgroup2: unknown option "memory_recursiveprot"
vfs_read+0x194/0x3c0 fs/read_write.c:452
ksys_read+0x12b/0x2a0 fs/read_write.c:579
do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe

other info that might help us debug this:

Chain exists of:
&sig->cred_guard_mutex --> sb_writers#3 --> &p->lock

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(&p->lock);
lock(sb_writers#3);
lock(&p->lock);
lock(&sig->cred_guard_mutex);

*** DEADLOCK ***

2 locks held by syz-executor.5/14535:
#0: 0000000037d1272f (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x26f/0x310 fs/file.c:767
#1: 00000000e07b062c (&p->lock){+.+.}, at: seq_read+0x6b/0x11c0 fs/seq_file.c:164

stack backtrace:
CPU: 0 PID: 14535 Comm: syz-executor.5 Not tainted 4.19.211-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/16/2023
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x1fc/0x2ef lib/dump_stack.c:118
print_circular_bug.constprop.0.cold+0x2d7/0x41e kernel/locking/lockdep.c:1222
check_prev_add kernel/locking/lockdep.c:1866 [inline]
check_prevs_add kernel/locking/lockdep.c:1979 [inline]
validate_chain kernel/locking/lockdep.c:2420 [inline]
__lock_acquire+0x30c9/0x3ff0 kernel/locking/lockdep.c:3416
IPVS: ftp: loaded support on port[0] = 21
lock_acquire+0x170/0x3c0 kernel/locking/lockdep.c:3908
__mutex_lock_common kernel/locking/mutex.c:937 [inline]
__mutex_lock+0xd7/0x1190 kernel/locking/mutex.c:1078
cgroup: cgroup2: unknown option "memory_recursiveprot"
do_io_accounting fs/proc/base.c:2750 [inline]
proc_tgid_io_accounting+0x1cf/0x7f0 fs/proc/base.c:2799
proc_single_show+0xeb/0x170 fs/proc/base.c:755
seq_read+0x4e0/0x11c0 fs/seq_file.c:232
__vfs_read+0xf7/0x750 fs/read_write.c:416
vfs_read+0x194/0x3c0 fs/read_write.c:452
ksys_read+0x12b/0x2a0 fs/read_write.c:579
do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7fa2814e20f9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 19 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:00007fa27fa54168 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 00007fa281601f80 RCX: 00007fa2814e20f9
cgroup: cgroup2: unknown option "memory_recursiveprot"
RDX: 0000000000002020 RSI: 0000000020000840 RDI: 0000000000000003
RBP: 00007fa28153dae9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffc7a87baaf R14: 00007fa27fa54300 R15: 0000000000022000
cgroup: cgroup2: unknown option "memory_recursiveprot"
IPVS: ftp: loaded support on port[0] = 21
cgroup: cgroup2: unknown option "memory_recursiveprot"
IPVS: ftp: loaded support on port[0] = 21
cgroup: cgroup2: unknown option "memory_recursiveprot"
cgroup: cgroup2: unknown option "memory_recursiveprot"
cgroup: cgroup2: unknown option "memory_recursiveprot"
netlink: 7820 bytes leftover after parsing attributes in process `syz-executor.0'.
audit: type=1804 audit(1677432378.706:3103): pid=14822 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=invalid_pcr cause=open_writers comm="syz-executor.3" name="file0" dev="sda1" ino=14124 res=1
cgroup: cgroup2: unknown option "memory_recursiveprot"
cgroup: cgroup2: unknown option "memory_recursiveprot"
cgroup: cgroup2: unknown option "memory_recursiveprot"
cgroup: cgroup2: unknown option "memory_recursiveprot"
cgroup: cgroup2: unknown option "memory_recursiveprot"
cgroup: cgroup2: unknown option "memory_recursiveprot"
cgroup: cgroup2: unknown option "memory_recursiveprot"
cgroup: cgroup2: unknown option "memory_recursiveprot"
cgroup: cgroup2: unknown option "memory_recursiveprot"
cgroup: cgroup2: unknown option "memory_recursiveprot"
cgroup: cgroup2: unknown option "memory_recursiveprot"
cgroup: cgroup2: unknown option "memory_recursiveprot"
cgroup: cgroup2: unknown option "memory_recursiveprot"
cgroup: cgroup2: unknown option "memory_recursiveprot"
cgroup: cgroup2: unknown option "memory_recursiveprot"
cgroup: cgroup2: unknown option "memory_recursiveprot"
cgroup: cgroup2: unknown option "memory_recursiveprot"
cgroup: cgroup2: unknown option "memory_recursiveprot"
cgroup: cgroup2: unknown option "memory_recursiveprot"
cgroup: cgroup2: unknown option "memory_recursiveprot"
cgroup: cgroup2: unknown option "memory_recursiveprot"
cgroup: cgroup2: unknown option "memory_recursiveprot"
cgroup: cgroup2: unknown option "memory_recursiveprot"
cgroup: cgroup2: unknown option "memory_recursiveprot"
cgroup: cgroup2: unknown option "memory_recursiveprot"
cgroup: cgroup2: unknown option "memory_recursiveprot"
cgroup: cgroup2: unknown option "memory_recursiveprot"
cgroup: cgroup2: unknown option "memory_recursiveprot"
IPVS: ftp: loaded support on port[0] = 21
cgroup: cgroup2: unknown option "memory_recursiveprot"
cgroup: cgroup2: unknown option "memory_recursiveprot"
IPVS: ftp: loaded support on port[0] = 21
cgroup: cgroup2: unknown option "memory_recursiveprot"
cgroup: cgroup2: unknown option "memory_recursiveprot"
IPVS: ftp: loaded support on port[0] = 21


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.