syzbot

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BUG: KCSAN: data-race in do_nanosleep / watchdog

write to 0xffff888121e49050 of 8 bytes by task 8923 on cpu 0:
 do_nanosleep+0x1da/0x320 kernel/time/hrtimer.c:1886
 hrtimer_nanosleep+0x136/0x230 kernel/time/hrtimer.c:1932
 __do_sys_nanosleep kernel/time/hrtimer.c:1966 [inline]
 __se_sys_nanosleep kernel/time/hrtimer.c:1953 [inline]
 __x64_sys_nanosleep+0x14b/0x190 kernel/time/hrtimer.c:1953
 do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888121e49050 of 8 bytes by task 1925 on cpu 1:
 check_hung_uninterruptible_tasks kernel/hung_task.c:197 [inline]
 watchdog+0x2b8/0x960 kernel/hung_task.c:289
 kthread+0x203/0x230 kernel/kthread.c:268
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 1925 Comm: khungtaskd Not tainted 5.7.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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Kernel panic - not syncing: panic_on_warn set ...
CPU: 1 PID: 1925 Comm: khungtaskd Not tainted 5.7.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x11d/0x187 lib/dump_stack.c:118
 panic+0x210/0x640 kernel/panic.c:221
 kcsan_report.cold+0xc/0x1a kernel/kcsan/report.c:626
 kcsan_setup_watchpoint+0x3fb/0x440 kernel/kcsan/core.c:519
 check_hung_uninterruptible_tasks kernel/hung_task.c:197 [inline]
 watchdog+0x2b8/0x960 kernel/hung_task.c:289
 kthread+0x203/0x230 kernel/kthread.c:268
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352
Kernel Offset: disabled
Rebooting in 86400 seconds..