WARNING in update_curr

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    719fdd32 afs: Fix storage of cell names
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10e0f8a3100000
kernel config:  https://syzkaller.appspot.com/x/.config?x=ce0957b53c175ac4
dashboard link: https://syzkaller.appspot.com/bug?extid=64ee4429b2be89db53db
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)

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

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+64ee4429b2be89db53db@xxxxxxxxxxxxxxxxxxxxxxxxx

------------[ cut here ]------------
WARNING: CPU: 1 PID: 59 at kernel/sched/sched.h:1132 rq_clock_task kernel/sched/sched.h:1132 [inline]
WARNING: CPU: 1 PID: 59 at kernel/sched/sched.h:1132 update_curr+0x295/0x8a0 kernel/sched/fair.c:847
Kernel panic - not syncing: panic_on_warn set ...
CPU: 1 PID: 59 Comm: kworker/1:1 Not tainted 5.8.0-rc2-syzkaller #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014
Workqueue: events close_work
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x18f/0x20d lib/dump_stack.c:118
 panic+0x2e3/0x75c kernel/panic.c:231
 __warn.cold+0x2f/0x3a kernel/panic.c:600
 report_bug+0x271/0x2f0 lib/bug.c:198
 exc_invalid_op+0x1b9/0x370 arch/x86/kernel/traps.c:235
 asm_exc_invalid_op+0x12/0x20 arch/x86/include/asm/idtentry.h:563
RIP: 0010:rq_clock_task kernel/sched/sched.h:1132 [inline]
RIP: 0010:update_curr+0x295/0x8a0 kernel/sched/fair.c:847
Code: 80 3c 02 00 0f 85 5c 05 00 00 4c 01 65 20 e9 af fe ff ff 49 8d 7c 24 18 be ff ff ff ff e8 b3 38 8d 06 85 c0 0f 85 04 fe ff ff <0f> 0b e9 fd fd ff ff 4c 8d 73 80 0f 1f 44 00 00 65 44 8b 2d 63 ba
RSP: 0018:ffffc900004e8d88 EFLAGS: 00010046
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000001
RDX: dffffc0000000000 RSI: ffff88802d035e18 RDI: 0000000000000086
RBP: ffff8880280afc00 R08: 0000000000000000 R09: fffffbfff137464b
R10: ffffffff89ba3257 R11: 0000000000000000 R12: ffff88802d035e00
R13: 0000000000000000 R14: dffffc0000000000 R15: ffff888060f98180
 enqueue_entity+0x1eb/0x1830 kernel/sched/fair.c:4190
 enqueue_task_fair+0x1a0/0x1a30 kernel/sched/fair.c:5485
 enqueue_task kernel/sched/core.c:1295 [inline]
 activate_task+0x10d/0x3f0 kernel/sched/core.c:1317
 ttwu_do_activate+0xca/0x130 kernel/sched/core.c:2247
 sched_ttwu_pending+0x16f/0x200 kernel/sched/core.c:2297
 flush_smp_call_function_queue+0x409/0x6e0 kernel/smp.c:314
 __sysvec_call_function_single+0x98/0x490 arch/x86/kernel/smp.c:248
 asm_call_on_stack+0xf/0x20 arch/x86/entry/entry_64.S:711
 </IRQ>
 __run_on_irqstack arch/x86/include/asm/irq_stack.h:22 [inline]
 run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:48 [inline]
 sysvec_call_function_single+0x1bf/0x210 arch/x86/kernel/smp.c:243
 asm_sysvec_call_function_single+0x12/0x20 arch/x86/include/asm/idtentry.h:604
RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:765 [inline]
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:160 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0x8c/0xe0 kernel/locking/spinlock.c:191
Code: 48 c7 c0 80 b4 b4 89 48 ba 00 00 00 00 00 fc ff df 48 c1 e8 03 80 3c 10 00 75 37 48 83 3d 4b d7 d1 01 00 74 22 48 89 df 57 9d <0f> 1f 44 00 00 bf 01 00 00 00 e8 35 3f 6c f9 65 8b 05 6e 21 1f 78
RSP: 0018:ffffc900006c7d10 EFLAGS: 00000286
RAX: 1ffffffff1369690 RBX: 0000000000000286 RCX: 1ffffffff155c832
RDX: dffffc0000000000 RSI: 0000000000000000 RDI: 0000000000000286
RBP: ffff88802809e998 R08: 0000000000000000 R09: 0000000000000001
R10: ffffffff8c58db0f R11: fffffbfff18b1b61 R12: 0000000000000080
R13: ffff88802809e958 R14: ffff88802bdc0f00 R15: ffff88802cf35600
 process_one_work+0x965/0x1690 kernel/workqueue.c:2269
 worker_thread+0x96/0xe10 kernel/workqueue.c:2415
 kthread+0x3b5/0x4a0 kernel/kthread.c:291
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:293
Kernel Offset: disabled


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