BUG: corrupted list in dequeue_task_rt

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 7d549995d4e0 Merge tag 'for-linus' of git://git.kernel.org..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10dd40ae300000
kernel config: https://syzkaller.appspot.com/x/.config?x=40eef000d7648480
dashboard link: https://syzkaller.appspot.com/bug?extid=db2214c7dac2c8584512
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.1
CC: [da...@stgolabs.net dvh...@infradead.org linux-...@vger.kernel.org mi...@redhat.com pet...@infradead.org tg...@linutronix.de]

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+db2214...@syzkaller.appspotmail.com

list_del corruption. prev->next should be ffff88800010d928, but was 0000000000000000
------------[ cut here ]------------
kernel BUG at lib/list_debug.c:51!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 24357 Comm: syz-executor.2 Not tainted 5.14.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:__list_del_entry_valid.cold+0xf/0x4a lib/list_debug.c:51
Code: e8 93 73 f2 ff 0f 0b 48 89 f1 48 c7 c7 a0 b4 e3 89 4c 89 e6 e8 7f 73 f2 ff 0f 0b 48 89 ee 48 c7 c7 40 b6 e3 89 e8 6e 73 f2 ff <0f> 0b 4c 89 ea 48 89 ee 48 c7 c7 80 b5 e3 89 e8 5a 73 f2 ff 0f 0b
RSP: 0018:ffffc900027cf8c0 EFLAGS: 00010086
RAX: 0000000000000054 RBX: ffff88800010d920 RCX: 0000000000000000
RDX: 0000000000040000 RSI: ffffffff815d68c5 RDI: fffff520004f9f0a
RBP: ffff88800010d928 R08: 0000000000000054 R09: 0000000000000000
R10: ffffffff815d06fe R11: 0000000000000000 R12: ffff88800010d928
R13: 0000000000000000 R14: ffff88800010d938 R15: ffff88800010d930
FS: 00007fc72464a700(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000203ff030 CR3: 0000000016fed000 CR4: 0000000000350ef0
Call Trace:
__list_del_entry include/linux/list.h:132 [inline]
list_del_init include/linux/list.h:204 [inline]
plist_del+0xbc/0x480 lib/plist.c:127
dequeue_pushable_task kernel/sched/rt.c:389 [inline]
dequeue_task_rt+0xb2/0x230 kernel/sched/rt.c:1392
dequeue_task kernel/sched/core.c:1967 [inline]
deactivate_task kernel/sched/core.c:1981 [inline]
__schedule+0xc91/0x26f0 kernel/sched/core.c:5894
schedule+0xd3/0x270 kernel/sched/core.c:6019
freezable_schedule include/linux/freezer.h:172 [inline]
futex_wait_queue_me+0x25a/0x520 kernel/futex.c:2602
futex_wait+0x1db/0x5f0 kernel/futex.c:2704
do_futex+0x250/0x1770 kernel/futex.c:3730
__do_sys_futex+0xdc/0x3b0 kernel/futex.c:3807
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x4665e9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fc72464a218 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: ffffffffffffffda RBX: 000000000056c040 RCX: 00000000004665e9
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 000000000056c040
RBP: 000000000056c038 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056c044
R13: 00007ffd90d35e0f R14: 00007fc72464a300 R15: 0000000000022000
Modules linked in:

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[syzbot]

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