possible deadlock in vcs_write (2)

[syzbot]

Hello,

syzkaller hit the following crash on
43ff2f4db9d0f76452b77cfa645f02b471143b24
git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/master
compiler: gcc (GCC) 7.1.1 20170620
.config is attached
Raw console output is attached.

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


WARNING: possible circular locking dependency detected
4.14.0+ #176 Not tainted
------------------------------------------------------
syz-executor2/9037 is trying to acquire lock:
(console_lock){+.+.}, at: [<ffffffff828293fd>] vcs_write+0x14d/0xca0
drivers/tty/vt/vc_screen.c:397

but task is already holding lock:
(&pipe->mutex/1){+.+.}, at: [<ffffffff81acbc96>] pipe_lock_nested
fs/pipe.c:67 [inline]
(&pipe->mutex/1){+.+.}, at: [<ffffffff81acbc96>] pipe_lock+0x56/0x70
fs/pipe.c:75

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (&pipe->mutex/1){+.+.}:
lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:4007
__mutex_lock_common kernel/locking/mutex.c:756 [inline]
__mutex_lock+0x16f/0x1a80 kernel/locking/mutex.c:893
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908
pipe_lock_nested fs/pipe.c:67 [inline]
pipe_lock+0x56/0x70 fs/pipe.c:75
iter_file_splice_write+0x264/0xf30 fs/splice.c:699
do_splice_from fs/splice.c:851 [inline]
do_splice fs/splice.c:1147 [inline]
SYSC_splice fs/splice.c:1402 [inline]
SyS_splice+0x7d5/0x1630 fs/splice.c:1382
entry_SYSCALL_64_fastpath+0x1f/0x96

-> #2 (sb_writers){.+.+}:
__wake_up_common_lock+0x190/0x310 kernel/sched/wait.c:124

-> #1 ((completion)&req.done){+.+.}:
lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:4007
complete_acquire include/linux/completion.h:40 [inline]
__wait_for_common kernel/sched/completion.c:109 [inline]
wait_for_common kernel/sched/completion.c:123 [inline]
wait_for_completion+0xcb/0x7b0 kernel/sched/completion.c:144
devtmpfs_create_node+0x32b/0x4a0 drivers/base/devtmpfs.c:115
device_add+0x120f/0x1640 drivers/base/core.c:1824
device_create_groups_vargs+0x1f3/0x250 drivers/base/core.c:2430
device_create_vargs drivers/base/core.c:2470 [inline]
device_create+0xda/0x110 drivers/base/core.c:2506
vcs_make_sysfs+0x35/0x60 drivers/tty/vt/vc_screen.c:629
vc_allocate+0x4b7/0x6b0 drivers/tty/vt/vt.c:795
con_install+0x52/0x440 drivers/tty/vt/vt.c:2876
tty_driver_install_tty drivers/tty/tty_io.c:1214 [inline]
tty_init_dev+0xf6/0x4a0 drivers/tty/tty_io.c:1314
tty_open_by_driver drivers/tty/tty_io.c:1941 [inline]
tty_open+0x608/0xab0 drivers/tty/tty_io.c:1989
chrdev_open+0x257/0x730 fs/char_dev.c:417
do_dentry_open+0x682/0xd70 fs/open.c:752
vfs_open+0x107/0x230 fs/open.c:866
do_last fs/namei.c:3388 [inline]
path_openat+0x1157/0x3530 fs/namei.c:3528
do_filp_open+0x25b/0x3b0 fs/namei.c:3563
do_sys_open+0x502/0x6d0 fs/open.c:1059
SYSC_open fs/open.c:1077 [inline]
SyS_open+0x2d/0x40 fs/open.c:1072
entry_SYSCALL_64_fastpath+0x1f/0x96

-> #0 (console_lock){+.+.}:
check_prevs_add kernel/locking/lockdep.c:2032 [inline]
validate_chain kernel/locking/lockdep.c:2474 [inline]
__lock_acquire+0x33ad/0x4840 kernel/locking/lockdep.c:3503
lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:4007
console_lock+0x4b/0x80 kernel/printk/printk.c:2047
vcs_write+0x14d/0xca0 drivers/tty/vt/vc_screen.c:397
__vfs_write+0xef/0x970 fs/read_write.c:480
__kernel_write+0xfe/0x350 fs/read_write.c:501
write_pipe_buf+0x175/0x220 fs/splice.c:797
splice_from_pipe_feed fs/splice.c:502 [inline]
__splice_from_pipe+0x328/0x730 fs/splice.c:626
splice_from_pipe+0x1e9/0x330 fs/splice.c:661
default_file_splice_write+0x40/0x90 fs/splice.c:809
do_splice_from fs/splice.c:851 [inline]
do_splice fs/splice.c:1147 [inline]
SYSC_splice fs/splice.c:1402 [inline]
SyS_splice+0x7d5/0x1630 fs/splice.c:1382
entry_SYSCALL_64_fastpath+0x1f/0x96

other info that might help us debug this:

Chain exists of:
console_lock --> sb_writers --> &pipe->mutex/1

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(&pipe->mutex/1);
lock(sb_writers);
lock(&pipe->mutex/1);
lock(console_lock);

*** DEADLOCK ***

1 lock held by syz-executor2/9037:
#0: (&pipe->mutex/1){+.+.}, at: [<ffffffff81acbc96>] pipe_lock_nested
fs/pipe.c:67 [inline]
#0: (&pipe->mutex/1){+.+.}, at: [<ffffffff81acbc96>] pipe_lock+0x56/0x70
fs/pipe.c:75

stack backtrace:
CPU: 0 PID: 9037 Comm: syz-executor2 Not tainted 4.14.0+ #176
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+0x194/0x257 lib/dump_stack.c:53
print_circular_bug+0x42d/0x610 kernel/locking/lockdep.c:1272
check_prev_add+0x8b1/0x1580 kernel/locking/lockdep.c:1915
check_prevs_add kernel/locking/lockdep.c:2032 [inline]
validate_chain kernel/locking/lockdep.c:2474 [inline]
__lock_acquire+0x33ad/0x4840 kernel/locking/lockdep.c:3503
lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:4007
console_lock+0x4b/0x80 kernel/printk/printk.c:2047
vcs_write+0x14d/0xca0 drivers/tty/vt/vc_screen.c:397
__vfs_write+0xef/0x970 fs/read_write.c:480
__kernel_write+0xfe/0x350 fs/read_write.c:501
write_pipe_buf+0x175/0x220 fs/splice.c:797
splice_from_pipe_feed fs/splice.c:502 [inline]
__splice_from_pipe+0x328/0x730 fs/splice.c:626
splice_from_pipe+0x1e9/0x330 fs/splice.c:661
default_file_splice_write+0x40/0x90 fs/splice.c:809
do_splice_from fs/splice.c:851 [inline]
do_splice fs/splice.c:1147 [inline]
SYSC_splice fs/splice.c:1402 [inline]
SyS_splice+0x7d5/0x1630 fs/splice.c:1382
entry_SYSCALL_64_fastpath+0x1f/0x96
RIP: 0033:0x452879
RSP: 002b:00007fec20a33be8 EFLAGS: 00000212 ORIG_RAX: 0000000000000113
RAX: ffffffffffffffda RBX: 0000000000758020 RCX: 0000000000452879
RDX: 0000000000000018 RSI: 0000000000000000 RDI: 0000000000000019
RBP: 0000000000000082 R08: 00000000fffff5fc R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000212 R12: 00000000006f6ef0
R13: 00000000ffffffff R14: 00007fec20a346d4 R15: 0000000000000000
device gre0 entered promiscuous mode
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FAULT_INJECTION: forcing a failure.
name failslab, interval 1, probability 0, space 0, times 1
device gre0 entered promiscuous mode
FAULT_INJECTION: forcing a failure.
name failslab, interval 1, probability 0, space 0, times 1
CPU: 1 PID: 11211 Comm: syz-executor3 Not tainted 4.14.0+ #176
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+0x194/0x257 lib/dump_stack.c:53
fail_dump lib/fault-inject.c:51 [inline]
should_fail+0x8c0/0xa40 lib/fault-inject.c:149
should_failslab+0xec/0x120 mm/failslab.c:32
slab_pre_alloc_hook mm/slab.h:423 [inline]
slab_alloc_node mm/slab.c:3305 [inline]
kmem_cache_alloc_node+0x56/0x760 mm/slab.c:3650
__alloc_skb+0xf1/0x740 net/core/skbuff.c:194
alloc_skb include/linux/skbuff.h:976 [inline]
pfkey_sendmsg+0x20f/0x9f0 net/key/af_key.c:3635
sock_sendmsg_nosec net/socket.c:633 [inline]
sock_sendmsg+0xca/0x110 net/socket.c:643
___sys_sendmsg+0x75b/0x8a0 net/socket.c:2049
__sys_sendmsg+0xe5/0x210 net/socket.c:2083
SYSC_sendmsg net/socket.c:2094 [inline]
SyS_sendmsg+0x2d/0x50 net/socket.c:2090
entry_SYSCALL_64_fastpath+0x1f/0x96
RIP: 0033:0x452879
RSP: 002b:00007f55b2837be8 EFLAGS: 00000212 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 0000000000758020 RCX: 0000000000452879
RDX: 0000000000000000 RSI: 0000000020dfafc8 RDI: 0000000000000014
RBP: 00007f55b2837a20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000212 R12: 00000000004b757e
R13: 00007f55b2837b58 R14: 00000000004b758e R15: 0000000000000000
device gre0 entered promiscuous mode
FAULT_INJECTION: forcing a failure.
name fail_page_alloc, interval 1, probability 0, space 0, times 1
CPU: 0 PID: 11217 Comm: syz-executor1 Not tainted 4.14.0+ #176
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+0x194/0x257 lib/dump_stack.c:53
fail_dump lib/fault-inject.c:51 [inline]
should_fail+0x8c0/0xa40 lib/fault-inject.c:149
should_fail_alloc_page mm/page_alloc.c:2897 [inline]
prepare_alloc_pages mm/page_alloc.c:4152 [inline]
__alloc_pages_nodemask+0x338/0xd80 mm/page_alloc.c:4191
alloc_pages_current+0xb6/0x1e0 mm/mempolicy.c:2038
alloc_pages include/linux/gfp.h:506 [inline]
skb_page_frag_refill+0x358/0x5f0 net/core/sock.c:2203
tun_build_skb.isra.42+0x2e8/0x1710 drivers/net/tun.c:1290
tun_get_user+0x1e0f/0x21d0 drivers/net/tun.c:1456
tun_chr_write_iter+0xde/0x190 drivers/net/tun.c:1582
call_write_iter include/linux/fs.h:1771 [inline]
do_iter_readv_writev+0x531/0x7f0 fs/read_write.c:674
do_iter_write+0x15a/0x540 fs/read_write.c:953
vfs_writev+0x18a/0x340 fs/read_write.c:998
do_writev+0xfc/0x2a0 fs/read_write.c:1033
SYSC_writev fs/read_write.c:1106 [inline]
SyS_writev+0x27/0x30 fs/read_write.c:1103
entry_SYSCALL_64_fastpath+0x1f/0x96
RIP: 0033:0x452751
RSP: 002b:00007fea43d85b10 EFLAGS: 00000293 ORIG_RAX: 0000000000000014
RAX: ffffffffffffffda RBX: 000000000000004e RCX: 0000000000452751
RDX: 0000000000000001 RSI: 00007fea43d85b60 RDI: 0000000000000012
RBP: 00007fea43d85a20 R08: 0000000000000000 R09: 0000000000000000
R10: 000000000000004e R11: 0000000000000293 R12: 00000000004b757e
R13: 00007fea43d85b58 R14: 00000000004b758e R15: 0000000000000000
device gre0 entered promiscuous mode
FAULT_INJECTION: forcing a failure.
name failslab, interval 1, probability 0, space 0, times 0
CPU: 1 PID: 11220 Comm: syz-executor3 Not tainted 4.14.0+ #176
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+0x194/0x257 lib/dump_stack.c:53
fail_dump lib/fault-inject.c:51 [inline]
should_fail+0x8c0/0xa40 lib/fault-inject.c:149
should_failslab+0xec/0x120 mm/failslab.c:32
slab_pre_alloc_hook mm/slab.h:423 [inline]
slab_alloc_node mm/slab.c:3305 [inline]
kmem_cache_alloc_node_trace+0x5a/0x760 mm/slab.c:3669
__do_kmalloc_node mm/slab.c:3689 [inline]
__kmalloc_node_track_caller+0x33/0x70 mm/slab.c:3704
__kmalloc_reserve.isra.41+0x41/0xd0 net/core/skbuff.c:138
__alloc_skb+0x13b/0x740 net/core/skbuff.c:206
alloc_skb include/linux/skbuff.h:976 [inline]
pfkey_sendmsg+0x20f/0x9f0 net/key/af_key.c:3635
sock_sendmsg_nosec net/socket.c:633 [inline]
sock_sendmsg+0xca/0x110 net/socket.c:643
___sys_sendmsg+0x75b/0x8a0 net/socket.c:2049
__sys_sendmsg+0xe5/0x210 net/socket.c:2083
SYSC_sendmsg net/socket.c:2094 [inline]
SyS_sendmsg+0x2d/0x50 net/socket.c:2090
entry_SYSCALL_64_fastpath+0x1f/0x96
RIP: 0033:0x452879
RSP: 002b:00007f55b2837be8 EFLAGS: 00000212 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 0000000000758020 RCX: 0000000000452879
RDX: 0000000000000000 RSI: 0000000020dfafc8 RDI: 0000000000000014
RBP: 00007f55b2837a20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000212 R12: 00000000004b757e
R13: 00007f55b2837b58 R14: 00000000004b758e R15: 0000000000000000
FAULT_INJECTION: forcing a failure.
name failslab, interval 1, probability 0, space 0, times 0
CPU: 1 PID: 11222 Comm: syz-executor1 Not tainted 4.14.0+ #176
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+0x194/0x257 lib/dump_stack.c:53
fail_dump lib/fault-inject.c:51 [inline]
should_fail+0x8c0/0xa40 lib/fault-inject.c:149
should_failslab+0xec/0x120 mm/failslab.c:32
slab_pre_alloc_hook mm/slab.h:423 [inline]
slab_alloc mm/slab.c:3384 [inline]
kmem_cache_alloc+0x47/0x760 mm/slab.c:3560
__build_skb+0x9d/0x450 net/core/skbuff.c:284
build_skb+0x6f/0x260 net/core/skbuff.c:316
tun_build_skb.isra.42+0x96e/0x1710 drivers/net/tun.c:1347
tun_get_user+0x1e0f/0x21d0 drivers/net/tun.c:1456
tun_chr_write_iter+0xde/0x190 drivers/net/tun.c:1582
call_write_iter include/linux/fs.h:1771 [inline]
do_iter_readv_writev+0x531/0x7f0 fs/read_write.c:674
do_iter_write+0x15a/0x540 fs/read_write.c:953
vfs_writev+0x18a/0x340 fs/read_write.c:998
do_writev+0xfc/0x2a0 fs/read_write.c:1033
SYSC_writev fs/read_write.c:1106 [inline]
SyS_writev+0x27/0x30 fs/read_write.c:1103
entry_SYSCALL_64_fastpath+0x1f/0x96
RIP: 0033:0x452751
RSP: 002b:00007fea43d85b10 EFLAGS: 00000293 ORIG_RAX: 0000000000000014
RAX: ffffffffffffffda RBX: 000000000000004e RCX: 0000000000452751
RDX: 0000000000000001 RSI: 00007fea43d85b60 RDI: 0000000000000012
RBP: 00007fea43d85a20 R08: 0000000000000000 R09: 0000000000000000
R10: 000000000000004e R11: 0000000000000293 R12: 00000000004b757e
R13: 00007fea43d85b58 R14: 00000000004b758e R15: 0000000000000000
FAULT_INJECTION: forcing a failure.
name failslab, interval 1, probability 0, space 0, times 0
CPU: 1 PID: 11210 Comm: syz-executor2 Not tainted 4.14.0+ #176
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+0x194/0x257 lib/dump_stack.c:53
fail_dump lib/fault-inject.c:51 [inline]
should_fail+0x8c0/0xa40 lib/fault-inject.c:149
should_failslab+0xec/0x120 mm/failslab.c:32
slab_pre_alloc_hook mm/slab.h:423 [inline]
slab_alloc_node mm/slab.c:3305 [inline]
kmem_cache_alloc_node+0x56/0x760 mm/slab.c:3650
__alloc_skb+0xf1/0x740 net/core/skbuff.c:194


---
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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.