syzbot


possible deadlock in proc_tid_io_accounting (2)

Status: upstream: reported on 2022/05/27 23:12
Reported-by: syzbot+8bce10ee506a21ac4794@syzkaller.appspotmail.com
First crash: 81d, last: 81d
similar bugs (3):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-4.19 possible deadlock in proc_tid_io_accounting 39 15d 694d 0/1 upstream: reported on 2020/09/21 07:35
upstream possible deadlock in proc_tid_io_accounting 1 1027d 1023d 0/23 auto-closed as invalid on 2020/02/21 09:02
linux-4.14 possible deadlock in proc_tid_io_accounting 3 501d 581d 0/1 auto-closed as invalid on 2021/07/31 05:58

Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
4.14.281-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.0/12820 is trying to acquire lock:
 (&sig->cred_guard_mutex){+.+.}, at: [<ffffffff81a0d024>] do_io_accounting fs/proc/base.c:2738 [inline]
 (&sig->cred_guard_mutex){+.+.}, at: [<ffffffff81a0d024>] proc_tid_io_accounting+0x184/0x290 fs/proc/base.c:2781

but task is already holding lock:
 (&p->lock){+.+.}, at: [<ffffffff818ef78a>] seq_read+0xba/0x1180 fs/seq_file.c:168

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (&p->lock){+.+.}:
       __mutex_lock_common kernel/locking/mutex.c:756 [inline]
       __mutex_lock+0xc4/0x1310 kernel/locking/mutex.c:893
       seq_read+0xba/0x1180 fs/seq_file.c:168
       proc_reg_read+0xee/0x1a0 fs/proc/inode.c:217
       do_loop_readv_writev fs/read_write.c:695 [inline]
       do_loop_readv_writev fs/read_write.c:682 [inline]
       do_iter_read+0x3eb/0x5b0 fs/read_write.c:919
       vfs_readv+0xc8/0x120 fs/read_write.c:981
       kernel_readv fs/splice.c:361 [inline]
       default_file_splice_read+0x418/0x910 fs/splice.c:416
       do_splice_to+0xfb/0x140 fs/splice.c:880
       splice_direct_to_actor+0x207/0x730 fs/splice.c:952
       do_splice_direct+0x164/0x210 fs/splice.c:1061
       do_sendfile+0x47f/0xb30 fs/read_write.c:1441
       SYSC_sendfile64 fs/read_write.c:1502 [inline]
       SyS_sendfile64+0xff/0x110 fs/read_write.c:1488
       do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
       entry_SYSCALL_64_after_hwframe+0x46/0xbb

-> #2 (sb_writers#3){.+.+}:
       percpu_down_read_preempt_disable include/linux/percpu-rwsem.h:36 [inline]
       percpu_down_read include/linux/percpu-rwsem.h:59 [inline]
       __sb_start_write+0x64/0x260 fs/super.c:1342
       sb_start_write include/linux/fs.h:1551 [inline]
       mnt_want_write+0x3a/0xb0 fs/namespace.c:386
       ovl_create_object+0x75/0x1d0 fs/overlayfs/dir.c:538
       lookup_open+0x77a/0x1750 fs/namei.c:3241
       do_last fs/namei.c:3334 [inline]
       path_openat+0xe08/0x2970 fs/namei.c:3569
       do_filp_open+0x179/0x3c0 fs/namei.c:3603
       do_sys_open+0x296/0x410 fs/open.c:1081
       do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
       entry_SYSCALL_64_after_hwframe+0x46/0xbb

-> #1 (&ovl_i_mutex_dir_key[depth]){++++}:
       down_read+0x36/0x80 kernel/locking/rwsem.c:24
       inode_lock_shared include/linux/fs.h:729 [inline]
       do_last fs/namei.c:3333 [inline]
       path_openat+0x149b/0x2970 fs/namei.c:3569
       do_filp_open+0x179/0x3c0 fs/namei.c:3603
       do_open_execat+0xd3/0x450 fs/exec.c:849
       do_execveat_common+0x711/0x1f30 fs/exec.c:1755
       do_execve fs/exec.c:1860 [inline]
       SYSC_execve fs/exec.c:1941 [inline]
       SyS_execve+0x3b/0x50 fs/exec.c:1936
       do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
       entry_SYSCALL_64_after_hwframe+0x46/0xbb

-> #0 (&sig->cred_guard_mutex){+.+.}:
       lock_acquire+0x170/0x3f0 kernel/locking/lockdep.c:3998
       __mutex_lock_common kernel/locking/mutex.c:756 [inline]
       __mutex_lock+0xc4/0x1310 kernel/locking/mutex.c:893
       do_io_accounting fs/proc/base.c:2738 [inline]
       proc_tid_io_accounting+0x184/0x290 fs/proc/base.c:2781
       proc_single_show+0xe7/0x150 fs/proc/base.c:761
       seq_read+0x4e4/0x1180 fs/seq_file.c:240
       do_loop_readv_writev fs/read_write.c:695 [inline]
       do_loop_readv_writev fs/read_write.c:682 [inline]
       do_iter_read+0x3eb/0x5b0 fs/read_write.c:919
       vfs_readv+0xc8/0x120 fs/read_write.c:981
       do_preadv fs/read_write.c:1065 [inline]
       SYSC_preadv fs/read_write.c:1115 [inline]
       SyS_preadv+0x15a/0x200 fs/read_write.c:1110
       do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
       entry_SYSCALL_64_after_hwframe+0x46/0xbb

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 ***

1 lock held by syz-executor.0/12820:
 #0:  (&p->lock){+.+.}, at: [<ffffffff818ef78a>] seq_read+0xba/0x1180 fs/seq_file.c:168

stack backtrace:
CPU: 0 PID: 12820 Comm: syz-executor.0 Not tainted 4.14.281-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x1b2/0x281 lib/dump_stack.c:58
 print_circular_bug.constprop.0.cold+0x2d7/0x41e kernel/locking/lockdep.c:1258
 check_prev_add kernel/locking/lockdep.c:1905 [inline]
 check_prevs_add kernel/locking/lockdep.c:2022 [inline]
 validate_chain kernel/locking/lockdep.c:2464 [inline]
 __lock_acquire+0x2e0e/0x3f20 kernel/locking/lockdep.c:3491
 lock_acquire+0x170/0x3f0 kernel/locking/lockdep.c:3998
 __mutex_lock_common kernel/locking/mutex.c:756 [inline]
 __mutex_lock+0xc4/0x1310 kernel/locking/mutex.c:893
 do_io_accounting fs/proc/base.c:2738 [inline]
 proc_tid_io_accounting+0x184/0x290 fs/proc/base.c:2781
 proc_single_show+0xe7/0x150 fs/proc/base.c:761
 seq_read+0x4e4/0x1180 fs/seq_file.c:240
 do_loop_readv_writev fs/read_write.c:695 [inline]
 do_loop_readv_writev fs/read_write.c:682 [inline]
 do_iter_read+0x3eb/0x5b0 fs/read_write.c:919
 vfs_readv+0xc8/0x120 fs/read_write.c:981
 do_preadv fs/read_write.c:1065 [inline]
 SYSC_preadv fs/read_write.c:1115 [inline]
 SyS_preadv+0x15a/0x200 fs/read_write.c:1110
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x7f92ec584109
RSP: 002b:00007f92eaef9168 EFLAGS: 00000246 ORIG_RAX: 0000000000000127
RAX: ffffffffffffffda RBX: 00007f92ec696f60 RCX: 00007f92ec584109
RDX: 0000000000000001 RSI: 0000000020000000 RDI: 0000000000000005
RBP: 00007f92ec5de08d R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffd1462d6ef R14: 00007f92eaef9300 R15: 0000000000022000
unregister_netdevice: waiting for ip6gre0 to become free. Usage count = -1
audit: type=1804 audit(1653693109.535:25): pid=12835 uid=0 auid=4294967295 ses=4294967295 op="invalid_pcr" cause="open_writers" comm="syz-executor.5" name="/root/syzkaller-testdir427273665/syzkaller.dufaFB/111/file0" dev="sda1" ino=14332 res=1
8021q: adding VLAN 0 to HW filter on device team0
bond0: Enslaving team0 as an active interface with an up link
bond0: Releasing backup interface team0
bridge0: port 3(team0) entered blocking state
bridge0: port 3(team0) entered disabled state
device team0 entered promiscuous mode
device team_slave_0 entered promiscuous mode
device team_slave_1 entered promiscuous mode
EXT4-fs (loop5): mounted filesystem without journal. Opts: ,errors=continue
device team0 left promiscuous mode
device team_slave_0 left promiscuous mode
EXT4-fs error (device loop5): ext4_mb_generate_buddy:754: group 0, block bitmap and bg descriptor inconsistent: 50 vs 25 free clusters
device team_slave_1 left promiscuous mode
bridge0: port 3(team0) entered disabled state
8021q: adding VLAN 0 to HW filter on device team0
EXT4-fs (loop5): mounted filesystem without journal. Opts: ,errors=continue
bond0: Enslaving team0 as an active interface with an up link
bond0: Releasing backup interface team0
bridge0: port 3(team0) entered blocking state
bridge0: port 3(team0) entered disabled state
EXT4-fs error (device loop5): ext4_mb_generate_buddy:754: group 0, block bitmap and bg descriptor inconsistent: 50 vs 25 free clusters
device team0 entered promiscuous mode
device team_slave_0 entered promiscuous mode
device team_slave_1 entered promiscuous mode
device team0 left promiscuous mode
device team_slave_0 left promiscuous mode
device team_slave_1 left promiscuous mode
bridge0: port 3(team0) entered disabled state
EXT4-fs (loop5): mounted filesystem without journal. Opts: ,errors=continue
8021q: adding VLAN 0 to HW filter on device team0
EXT4-fs error (device loop5): ext4_mb_generate_buddy:754: group 0, block bitmap and bg descriptor inconsistent: 50 vs 25 free clusters
EXT4-fs (loop3): mounted filesystem without journal. Opts: ,errors=continue
bond0: Enslaving team0 as an active interface with an up link
bond0: Releasing backup interface team0
bridge0: port 3(team0) entered blocking state
bridge0: port 3(team0) entered disabled state
device team0 entered promiscuous mode
EXT4-fs error (device loop3): ext4_mb_generate_buddy:754: group 0, block bitmap and bg descriptor inconsistent: 50 vs 25 free clusters
device team_slave_0 entered promiscuous mode
device team_slave_1 entered promiscuous mode
EXT4-fs (loop5): mounted filesystem without journal. Opts: ,errors=continue
EXT4-fs (loop3): mounted filesystem without journal. Opts: ,errors=continue
EXT4-fs error (device loop5): ext4_mb_generate_buddy:754: group 0, block bitmap and bg descriptor inconsistent: 50 vs 25 free clusters
EXT4-fs error (device loop3): ext4_mb_generate_buddy:754: group 0, block bitmap and bg descriptor inconsistent: 50 vs 25 free clusters
EXT4-fs (loop3): mounted filesystem without journal. Opts: ,errors=continue
device team0 left promiscuous mode
device team_slave_0 left promiscuous mode
device team_slave_1 left promiscuous mode
bridge0: port 3(team0) entered disabled state
EXT4-fs error (device loop3): ext4_mb_generate_buddy:754: group 0, block bitmap and bg descriptor inconsistent: 50 vs 25 free clusters
8021q: adding VLAN 0 to HW filter on device team0
bond0: Enslaving team0 as an active interface with an up link
bond0: Releasing backup interface team0
bridge0: port 3(team0) entered blocking state
bridge0: port 3(team0) entered disabled state
device team0 entered promiscuous mode
device team_slave_0 entered promiscuous mode
device team_slave_1 entered promiscuous mode
syz-executor.1 (13204) used greatest stack depth: 23800 bytes left
audit: type=1800 audit(1653693116.456:26): pid=13346 uid=0 auid=4294967295 ses=4294967295 op="collect_data" cause="failed(directio)" comm="syz-executor.0" name="file0" dev="sda1" ino=14394 res=0
audit: type=1804 audit(1653693116.476:27): pid=13354 uid=0 auid=4294967295 ses=4294967295 op="invalid_pcr" cause="open_writers" comm="syz-executor.0" name="/root/syzkaller-testdir3828707222/syzkaller.BvU6uv/124/file0" dev="sda1" ino=14394 res=1
netlink: 32 bytes leftover after parsing attributes in process `syz-executor.3'.
netlink: 32 bytes leftover after parsing attributes in process `syz-executor.3'.
netlink: 32 bytes leftover after parsing attributes in process `syz-executor.3'.
netlink: 32 bytes leftover after parsing attributes in process `syz-executor.3'.
VFS: Can't find a Minix filesystem V1 | V2 | V3 on device loop1.
print_req_error: I/O error, dev loop1, sector 0
Buffer I/O error on dev loop1, logical block 0, async page read
print_req_error: I/O error, dev loop1, sector 4
Buffer I/O error on dev loop1, logical block 2, async page read
print_req_error: I/O error, dev loop1, sector 6
Buffer I/O error on dev loop1, logical block 3, async page read
VFS: Can't find a Minix filesystem V1 | V2 | V3 on device loop1.
VFS: Can't find a Minix filesystem V1 | V2 | V3 on device loop1.
print_req_error: I/O error, dev loop1, sector 0
Buffer I/O error on dev loop1, logical block 0, async page read
print_req_error: I/O error, dev loop1, sector 4
Buffer I/O error on dev loop1, logical block 2, async page read
print_req_error: I/O error, dev loop1, sector 6
Buffer I/O error on dev loop1, logical block 3, async page read
VFS: Can't find a Minix filesystem V1 | V2 | V3 on device loop5.
VFS: Can't find a Minix filesystem V1 | V2 | V3 on device loop1.
EXT4-fs warning (device sda1): verify_group_input:136: Cannot add at group 3125 (only 16 groups)
VFS: Can't find a Minix filesystem V1 | V2 | V3 on device loop5.
VFS: Can't find a Minix filesystem V1 | V2 | V3 on device loop5.
EXT4-fs (loop3): warning: mounting unchecked fs, running e2fsck is recommended
EXT4-fs warning (device loop3): ext4_update_dynamic_rev:793: updating to rev 1 because of new feature flag, running e2fsck is recommended
EXT4-fs (loop3): mounted filesystem without journal. Opts: ,errors=continue
print_req_error: I/O error, dev loop5, sector 0
Buffer I/O error on dev loop5, logical block 0, async page read
print_req_error: I/O error, dev loop5, sector 4
Buffer I/O error on dev loop5, logical block 2, async page read
print_req_error: I/O error, dev loop5, sector 6
Buffer I/O error on dev loop5, logical block 3, async page read
EXT4-fs (loop3): warning: mounting unchecked fs, running e2fsck is recommended
EXT4-fs warning (device loop3): ext4_update_dynamic_rev:793: updating to rev 1 because of new feature flag, running e2fsck is recommended
EXT4-fs (loop3): mounted filesystem without journal. Opts: ,errors=continue
EXT4-fs (loop1): mounting ext2 file system using the ext4 subsystem
print_req_error: I/O error, dev loop3, sector 0
EXT4-fs (loop1): mounted filesystem without journal. Opts: ,errors=continue
device vxlan0 entered promiscuous mode
EXT4-fs (loop1): re-mounted. Opts: (null)

Crashes (1):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci2-linux-4-14 2022/05/27 23:12 linux-4.14.y 501eec4f9e13 a46af346 .config log report info possible deadlock in proc_tid_io_accounting