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Subject[syzbot] possible deadlock in __fs_reclaim_acquire
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Hello,

syzbot found the following issue on:

HEAD commit: 3dbdb38e Merge branch 'for-5.14' of git://git.kernel.org/p..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1333db52300000
kernel config: https://syzkaller.appspot.com/x/.config?x=1700b0b2b41cd52c
dashboard link: https://syzkaller.appspot.com/bug?extid=127fd7828d6eeb611703
compiler: Debian clang version 11.0.1-2

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

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+127fd7828d6eeb611703@syzkaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
5.13.0-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.3/21469 is trying to acquire lock:
ffffffff8cfd6720 (fs_reclaim){+.+.}-{0:0}, at: __fs_reclaim_acquire+0x0/0x30 mm/page_alloc.c:4222

but task is already holding lock:
ffff8880b9b31088 (lock#2){-.-.}-{2:2}, at: local_lock_acquire+0x7/0x130 include/linux/local_lock_internal.h:41

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (lock#2){-.-.}-{2:2}:
lock_acquire+0x182/0x4a0 kernel/locking/lockdep.c:5625
local_lock_acquire+0x23/0x130 include/linux/local_lock_internal.h:42
rmqueue_pcplist+0x10c/0x4d0 mm/page_alloc.c:3675
rmqueue+0x1eb4/0x22e0 mm/page_alloc.c:3713
get_page_from_freelist+0x4b3/0xa30 mm/page_alloc.c:4175
__alloc_pages+0x26c/0x5f0 mm/page_alloc.c:5386
stack_depot_save+0x361/0x490 lib/stackdepot.c:303
kasan_save_stack+0x3e/0x50 mm/kasan/common.c:40
kasan_record_aux_stack+0xee/0x120 mm/kasan/generic.c:348
__call_rcu kernel/rcu/tree.c:3038 [inline]
call_rcu+0x1a0/0xa20 kernel/rcu/tree.c:3113
context_switch kernel/sched/core.c:4686 [inline]
__schedule+0xc0f/0x11f0 kernel/sched/core.c:5940
preempt_schedule_notrace+0x12c/0x170 kernel/sched/core.c:6179
preempt_schedule_notrace_thunk+0x16/0x18 arch/x86/entry/thunk_64.S:36
rcu_read_unlock_sched_notrace include/linux/rcupdate.h:809 [inline]
trace_lock_release+0x9f/0x140 include/trace/events/lock.h:58
lock_release+0x81/0x7b0 kernel/locking/lockdep.c:5636
might_alloc include/linux/sched/mm.h:199 [inline]
slab_pre_alloc_hook mm/slab.h:485 [inline]
slab_alloc_node mm/slub.c:2891 [inline]
slab_alloc mm/slub.c:2978 [inline]
kmem_cache_alloc+0x41/0x340 mm/slub.c:2983
kmem_cache_zalloc include/linux/slab.h:711 [inline]
__alloc_file+0x26/0x2f0 fs/file_table.c:101
alloc_empty_file+0xa9/0x1b0 fs/file_table.c:150
path_openat+0x119/0x39b0 fs/namei.c:3480
do_filp_open+0x221/0x460 fs/namei.c:3521
do_open_execat+0x16d/0x710 fs/exec.c:913
bprm_execve+0x505/0x1470 fs/exec.c:1809
kernel_execve+0x8ce/0x9a0 fs/exec.c:1977
call_usermodehelper_exec_async+0x262/0x3b0 kernel/umh.c:112
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

-> #0 (fs_reclaim){+.+.}-{0:0}:
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
__fs_reclaim_acquire+0x20/0x30 mm/page_alloc.c:4564
fs_reclaim_acquire+0x59/0xf0 mm/page_alloc.c:4578
prepare_alloc_pages+0x151/0x5a0 mm/page_alloc.c:5176
__alloc_pages+0x14d/0x5f0 mm/page_alloc.c:5375
stack_depot_save+0x361/0x490 lib/stackdepot.c:303
save_stack+0xf9/0x1f0 mm/page_owner.c:120
__set_page_owner+0x42/0x2f0 mm/page_owner.c:181
prep_new_page mm/page_alloc.c:2445 [inline]
__alloc_pages_bulk+0x9f2/0x1090 mm/page_alloc.c:5313
alloc_pages_bulk_array_node include/linux/gfp.h:557 [inline]
vm_area_alloc_pages mm/vmalloc.c:2775 [inline]
__vmalloc_area_node mm/vmalloc.c:2845 [inline]
__vmalloc_node_range+0x3ad/0x7f0 mm/vmalloc.c:2947
__vmalloc_node mm/vmalloc.c:2996 [inline]
vzalloc+0x75/0x80 mm/vmalloc.c:3066
n_tty_open+0x19/0x150 drivers/tty/n_tty.c:1914
tty_ldisc_open drivers/tty/tty_ldisc.c:464 [inline]
tty_ldisc_setup+0xcf/0x3c0 drivers/tty/tty_ldisc.c:781
tty_init_dev+0x271/0x4c0 drivers/tty/tty_io.c:1461
tty_open_by_driver drivers/tty/tty_io.c:2102 [inline]
tty_open+0x89a/0xdd0 drivers/tty/tty_io.c:2150
chrdev_open+0x53b/0x5f0 fs/char_dev.c:414
do_dentry_open+0x7cb/0x1010 fs/open.c:826
do_open fs/namei.c:3361 [inline]
path_openat+0x28e6/0x39b0 fs/namei.c:3494
do_filp_open+0x221/0x460 fs/namei.c:3521
do_sys_openat2+0x124/0x460 fs/open.c:1195
do_sys_open fs/open.c:1211 [inline]
__do_sys_openat fs/open.c:1227 [inline]
__se_sys_openat fs/open.c:1222 [inline]
__x64_sys_openat+0x243/0x290 fs/open.c:1222
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:

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(lock#2);
lock(fs_reclaim);
lock(lock#2);
lock(fs_reclaim);

*** DEADLOCK ***

4 locks held by syz-executor.3/21469:
#0: ffffffff8d5ca708 (tty_mutex){+.+.}-{3:3}, at: tty_open_by_driver drivers/tty/tty_io.c:2066 [inline]
#0: ffffffff8d5ca708 (tty_mutex){+.+.}-{3:3}, at: tty_open+0x235/0xdd0 drivers/tty/tty_io.c:2150
#1: ffff8880257541c0 (&tty->legacy_mutex){+.+.}-{3:3}, at: tty_init_dev+0x6a/0x4c0 drivers/tty/tty_io.c:1436
#2: ffff888025754098 (&tty->ldisc_sem){++++}-{0:0}, at: __tty_ldisc_lock drivers/tty/tty_ldisc.c:315 [inline]
#2: ffff888025754098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_lock+0x6a/0xb0 drivers/tty/tty_ldisc.c:339
#3: ffff8880b9b31088 (lock#2){-.-.}-{2:2}, at: local_lock_acquire+0x7/0x130 include/linux/local_lock_internal.h:41

stack backtrace:
CPU: 1 PID: 21469 Comm: syz-executor.3 Not tainted 5.13.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:79 [inline]
dump_stack_lvl+0x1ae/0x29f lib/dump_stack.c:96
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
__fs_reclaim_acquire+0x20/0x30 mm/page_alloc.c:4564
fs_reclaim_acquire+0x59/0xf0 mm/page_alloc.c:4578
prepare_alloc_pages+0x151/0x5a0 mm/page_alloc.c:5176
__alloc_pages+0x14d/0x5f0 mm/page_alloc.c:5375
stack_depot_save+0x361/0x490 lib/stackdepot.c:303
save_stack+0xf9/0x1f0 mm/page_owner.c:120
__set_page_owner+0x42/0x2f0 mm/page_owner.c:181
prep_new_page mm/page_alloc.c:2445 [inline]
__alloc_pages_bulk+0x9f2/0x1090 mm/page_alloc.c:5313
alloc_pages_bulk_array_node include/linux/gfp.h:557 [inline]
vm_area_alloc_pages mm/vmalloc.c:2775 [inline]
__vmalloc_area_node mm/vmalloc.c:2845 [inline]
__vmalloc_node_range+0x3ad/0x7f0 mm/vmalloc.c:2947
__vmalloc_node mm/vmalloc.c:2996 [inline]
vzalloc+0x75/0x80 mm/vmalloc.c:3066
n_tty_open+0x19/0x150 drivers/tty/n_tty.c:1914
tty_ldisc_open drivers/tty/tty_ldisc.c:464 [inline]
tty_ldisc_setup+0xcf/0x3c0 drivers/tty/tty_ldisc.c:781
tty_init_dev+0x271/0x4c0 drivers/tty/tty_io.c:1461
tty_open_by_driver drivers/tty/tty_io.c:2102 [inline]
tty_open+0x89a/0xdd0 drivers/tty/tty_io.c:2150
chrdev_open+0x53b/0x5f0 fs/char_dev.c:414
do_dentry_open+0x7cb/0x1010 fs/open.c:826
do_open fs/namei.c:3361 [inline]
path_openat+0x28e6/0x39b0 fs/namei.c:3494
do_filp_open+0x221/0x460 fs/namei.c:3521
do_sys_openat2+0x124/0x460 fs/open.c:1195
do_sys_open fs/open.c:1211 [inline]
__do_sys_openat fs/open.c:1227 [inline]
__se_sys_openat fs/open.c:1222 [inline]
__x64_sys_openat+0x243/0x290 fs/open.c:1222
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: 0033:0x4196c4
Code: 84 00 00 00 00 00 44 89 54 24 0c e8 96 f9 ff ff 44 8b 54 24 0c 44 89 e2 48 89 ee 41 89 c0 bf 9c ff ff ff b8 01 01 00 00 0f 05 <48> 3d 00 f0 ff ff 77 34 44 89 c7 89 44 24 0c e8 c8 f9 ff ff 8b 44
RSP: 002b:00007f7b60ac8cc0 EFLAGS: 00000293 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 000000000056bf80 RCX: 00000000004196c4
RDX: 0000000000000002 RSI: 00007f7b60ac8d60 RDI: 00000000ffffff9c
RBP: 00007f7b60ac8d60 R08: 0000000000000000 R09: 000000000000000e
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000002
R13: 00007ffc7de709ef R14: 00007f7b60ac9300 R15: 0000000000022000
BUG: sleeping function called from invalid context at mm/page_alloc.c:5179
in_atomic(): 0, irqs_disabled(): 1, non_block: 0, pid: 21469, name: syz-executor.3
INFO: lockdep is turned off.
irq event stamp: 200
hardirqs last enabled at (199): [<ffffffff89cf038b>] __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:160 [inline]
hardirqs last enabled at (199): [<ffffffff89cf038b>] _raw_spin_unlock_irqrestore+0x8b/0x120 kernel/locking/spinlock.c:191
hardirqs last disabled at (200): [<ffffffff81be4351>] __alloc_pages_bulk+0x801/0x1090 mm/page_alloc.c:5291
softirqs last enabled at (0): [<ffffffff814b0828>] copy_process+0x1498/0x5b30 kernel/fork.c:2065
softirqs last disabled at (0): [<0000000000000000>] 0x0
CPU: 1 PID: 21469 Comm: syz-executor.3 Not tainted 5.13.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:79 [inline]
dump_stack_lvl+0x1ae/0x29f lib/dump_stack.c:96
___might_sleep+0x4e5/0x6b0 kernel/sched/core.c:9153
prepare_alloc_pages+0x1c0/0x5a0 mm/page_alloc.c:5179
__alloc_pages+0x14d/0x5f0 mm/page_alloc.c:5375
stack_depot_save+0x361/0x490 lib/stackdepot.c:303
save_stack+0xf9/0x1f0 mm/page_owner.c:120
__set_page_owner+0x42/0x2f0 mm/page_owner.c:181
prep_new_page mm/page_alloc.c:2445 [inline]
__alloc_pages_bulk+0x9f2/0x1090 mm/page_alloc.c:5313
alloc_pages_bulk_array_node include/linux/gfp.h:557 [inline]
vm_area_alloc_pages mm/vmalloc.c:2775 [inline]
__vmalloc_area_node mm/vmalloc.c:2845 [inline]
__vmalloc_node_range+0x3ad/0x7f0 mm/vmalloc.c:2947
__vmalloc_node mm/vmalloc.c:2996 [inline]
vzalloc+0x75/0x80 mm/vmalloc.c:3066
n_tty_open+0x19/0x150 drivers/tty/n_tty.c:1914
tty_ldisc_open drivers/tty/tty_ldisc.c:464 [inline]
tty_ldisc_setup+0xcf/0x3c0 drivers/tty/tty_ldisc.c:781
tty_init_dev+0x271/0x4c0 drivers/tty/tty_io.c:1461
tty_open_by_driver drivers/tty/tty_io.c:2102 [inline]
tty_open+0x89a/0xdd0 drivers/tty/tty_io.c:2150
chrdev_open+0x53b/0x5f0 fs/char_dev.c:414
do_dentry_open+0x7cb/0x1010 fs/open.c:826
do_open fs/namei.c:3361 [inline]
path_openat+0x28e6/0x39b0 fs/namei.c:3494
do_filp_open+0x221/0x460 fs/namei.c:3521
do_sys_openat2+0x124/0x460 fs/open.c:1195
do_sys_open fs/open.c:1211 [inline]
__do_sys_openat fs/open.c:1227 [inline]
__se_sys_openat fs/open.c:1222 [inline]
__x64_sys_openat+0x243/0x290 fs/open.c:1222
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: 0033:0x4196c4
Code: 84 00 00 00 00 00 44 89 54 24 0c e8 96 f9 ff ff 44 8b 54 24 0c 44 89 e2 48 89 ee 41 89 c0 bf 9c ff ff ff b8 01 01 00 00 0f 05 <48> 3d 00 f0 ff ff 77 34 44 89 c7 89 44 24 0c e8 c8 f9 ff ff 8b 44
RSP: 002b:00007f7b60ac8cc0 EFLAGS: 00000293 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 000000000056bf80 RCX: 00000000004196c4
RDX: 0000000000000002 RSI: 00007f7b60ac8d60 RDI: 00000000ffffff9c
RBP: 00007f7b60ac8d60 R08: 0000000000000000 R09: 000000000000000e
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000002
R13: 00007ffc7de709ef R14: 00007f7b60ac9300 R15: 0000000000022000


---
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 syzkaller@googlegroups.com.

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

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