syzbot

==================================================================
BUG: KCSAN: data-race in __mutex_lock.isra.0 / do_signal_stop

write to 0xffff88808d876050 of 8 bytes by task 17735 on cpu 1:
 __mutex_lock_common kernel/locking/mutex.c:1059 [inline]
 __mutex_lock.isra.0+0x47f/0x740 kernel/locking/mutex.c:1103
 __mutex_lock_slowpath+0x1f/0x30 kernel/locking/mutex.c:1364
 mutex_lock+0x2d/0x40 kernel/locking/mutex.c:284
 __fdget_pos+0xeb/0x100 fs/file.c:801
 fdget_pos include/linux/file.h:72 [inline]
 ksys_write+0x3f/0x1b0 fs/read_write.c:602
 __do_sys_write fs/read_write.c:623 [inline]
 __se_sys_write fs/read_write.c:620 [inline]
 __x64_sys_write+0x4c/0x60 fs/read_write.c:620
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88808d876050 of 8 bytes by task 17741 on cpu 0:
 do_signal_stop+0x3e3/0x500 kernel/signal.c:2348
 get_signal+0x61b/0x1320 kernel/signal.c:2694
 do_signal+0x3b/0xbf0 arch/x86/kernel/signal.c:815
 exit_to_usermode_loop+0x250/0x2c0 arch/x86/entry/common.c:159
 prepare_exit_to_usermode arch/x86/entry/common.c:194 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:274 [inline]
 do_syscall_64+0x353/0x370 arch/x86/entry/common.c:300
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 17741 Comm: syz-executor.2 Not tainted 5.4.0-rc6+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================
Kernel panic - not syncing: panic_on_warn set ...
CPU: 0 PID: 17741 Comm: syz-executor.2 Not tainted 5.4.0-rc6+ #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+0xf5/0x159 lib/dump_stack.c:113
 panic+0x210/0x640 kernel/panic.c:221
 kcsan_report.cold+0xc/0xe kernel/kcsan/report.c:302
 kcsan_setup_watchpoint+0x3fe/0x410 kernel/kcsan/core.c:357
 check_access kernel/kcsan/core.c:409 [inline]
 __tsan_read8+0x145/0x1f0 kernel/kcsan/core.c:530
 do_signal_stop+0x3e3/0x500 kernel/signal.c:2348
 get_signal+0x61b/0x1320 kernel/signal.c:2694
 do_signal+0x3b/0xbf0 arch/x86/kernel/signal.c:815
 exit_to_usermode_loop+0x250/0x2c0 arch/x86/entry/common.c:159
 prepare_exit_to_usermode arch/x86/entry/common.c:194 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:274 [inline]
 do_syscall_64+0x353/0x370 arch/x86/entry/common.c:300
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45a219
Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fa403c1cc78 EFLAGS: 00000246 ORIG_RAX: 00000000000000c8
RAX: 0000000000000000 RBX: 0000000000000002 RCX: 000000000045a219
RDX: 0000000000000000 RSI: 0001000000000016 RDI: 000000000000042d
RBP: 000000000075c070 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fa403c1d6d4
R13: 00000000004ca14f R14: 00000000004e2088 R15: 00000000ffffffff
Shutting down cpus with NMI
Kernel Offset: disabled
Rebooting in 86400 seconds..