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Subject[syzbot] WARNING: suspicious RCU usage in get_timespec64
From
Hello,

syzbot found the following issue on:

HEAD commit: 5e46d1b7 reiserfs: update reiserfs_xattrs_initialized() co..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1125f831d00000
kernel config: https://syzkaller.appspot.com/x/.config?x=78ef1d159159890
dashboard link: https://syzkaller.appspot.com/bug?extid=88e4f02896967fe1ab0d

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+88e4f02896967fe1ab0d@syzkaller.appspotmail.com

=============================
WARNING: suspicious RCU usage
5.12.0-rc5-syzkaller #0 Not tainted
-----------------------------
kernel/sched/core.c:8294 Illegal context switch in RCU-sched read-side critical section!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 0
3 locks held by syz-executor.4/8418:
#0:
ffff8880751d2b28
(
&p->pi_lock
){-.-.}-{2:2}
, at: try_to_wake_up+0x98/0x14a0 kernel/sched/core.c:3345
#1:
ffff8880b9d35258
(
&rq->lock
){-.-.}-{2:2}
, at: rq_lock kernel/sched/sched.h:1321 [inline]
, at: ttwu_queue kernel/sched/core.c:3184 [inline]
, at: try_to_wake_up+0x5e6/0x14a0 kernel/sched/core.c:3464
#2: ffff8880b9d1f948 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_change+0x142/0x220 kernel/sched/psi.c:807

stack backtrace:
CPU: 0 PID: 8418 Comm: syz-executor.4 Not tainted 5.12.0-rc5-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+0x141/0x1d7 lib/dump_stack.c:120
___might_sleep+0x266/0x2c0 kernel/sched/core.c:8294
__might_fault+0x6e/0x180 mm/memory.c:5018
_copy_from_user+0x27/0x180 lib/usercopy.c:13
copy_from_user include/linux/uaccess.h:192 [inline]
get_timespec64+0x75/0x220 kernel/time/time.c:787
__do_sys_clock_nanosleep kernel/time/posix-timers.c:1257 [inline]
__se_sys_clock_nanosleep kernel/time/posix-timers.c:1245 [inline]
__x64_sys_clock_nanosleep+0x1bb/0x430 kernel/time/posix-timers.c:1245
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x48a621
Code: 24 0c 89 3c 24 48 89 4c 24 18 e8 aa e7 ff ff 4c 8b 54 24 18 48 8b 54 24 10 41 89 c0 8b 74 24 0c 8b 3c 24 b8 e6 00 00 00 0f 05 <44> 89 c7 48 89 04 24 e8 e3 e7 ff ff 48 8b 04 24 eb 97 66 2e 0f 1f
RSP: 002b:00007fffe59fbd50 EFLAGS: 00000293 ORIG_RAX: 00000000000000e6
RAX: ffffffffffffffda RBX: 0000000000000294 RCX: 000000000048a621
RDX: 00007fffe59fbd90 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007fffe59fbe2c R08: 0000000000000000 R09: 00007fffe5b8a090
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000032
R13: 000000000005717a R14: 0000000000000003 R15: 00007fffe59fbe90


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
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syzbot will keep track of this issue. See:
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