syzbot

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BUG: KCSAN: data-race in rwsem_down_write_slowpath / watchdog

write to 0xffff888121e83050 of 8 bytes by task 28117 on cpu 0:
 rwsem_down_write_slowpath+0x3cb/0x950 kernel/locking/rwsem.c:1270
 __down_write_killable kernel/locking/rwsem.c:1403 [inline]
 down_write_killable+0x8e/0xb0 kernel/locking/rwsem.c:1547
 vm_mmap_pgoff+0xf1/0x190 mm/util.c:504
 ksys_mmap_pgoff+0x99/0x420 mm/mmap.c:1607
 __do_sys_mmap arch/x86/kernel/sys_x86_64.c:100 [inline]
 __se_sys_mmap arch/x86/kernel/sys_x86_64.c:91 [inline]
 __x64_sys_mmap+0x2e/0x40 arch/x86/kernel/sys_x86_64.c:91
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888121e83050 of 8 bytes by task 534 on cpu 1:
 check_hung_uninterruptible_tasks kernel/hung_task.c:197 [inline]
 watchdog+0x2b1/0x960 kernel/hung_task.c:289
 kthread+0x1d4/0x200 drivers/block/aoe/aoecmd.c:1253
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 534 Comm: khungtaskd Not tainted 5.5.0-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: 534 Comm: khungtaskd Not tainted 5.5.0-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/0x181 lib/dump_stack.c:118
 panic+0x210/0x640 kernel/panic.c:221
 kcsan_report.cold+0xc/0xd kernel/kcsan/report.c:313
 kcsan_setup_watchpoint+0x3fe/0x460 kernel/kcsan/core.c:416
 check_access kernel/kcsan/core.c:459 [inline]
 __tsan_read8+0xc6/0x100 kernel/kcsan/core.c:589
 check_hung_uninterruptible_tasks kernel/hung_task.c:197 [inline]
 watchdog+0x2b1/0x960 kernel/hung_task.c:289
 kthread+0x1d4/0x200 drivers/block/aoe/aoecmd.c:1253
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352
Kernel Offset: disabled
Rebooting in 86400 seconds..