==================================================================
BUG: KCSAN: data-race in atime_needs_update / shmem_unlink

write to 0xffff888102529868 of 16 bytes by task 4028 on cpu 0:
 shmem_unlink+0xe8/0x150 mm/shmem.c:2981
 vfs_unlink+0x225/0x3e0 fs/namei.c:3991
 do_unlinkat+0x32b/0x530 fs/namei.c:4055
 __do_sys_unlink fs/namei.c:4102 [inline]
 __se_sys_unlink fs/namei.c:4100 [inline]
 __x64_sys_unlink+0x3b/0x50 fs/namei.c:4100
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888102529868 of 8 bytes by task 3890 on cpu 1:
 relatime_need_update fs/inode.c:1633 [inline]
 atime_needs_update+0x264/0x360 fs/inode.c:1721
 touch_atime+0x63/0x190 fs/inode.c:1736
 do_readlinkat+0x1d8/0x220 fs/stat.c:410
 __do_sys_readlink fs/stat.c:432 [inline]
 __se_sys_readlink fs/stat.c:429 [inline]
 __x64_sys_readlink+0x51/0x70 fs/stat.c:429
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 3890 Comm: udevd Not tainted 5.4.0-rc3+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================
Kernel panic - not syncing: panic_on_warn set ...
CPU: 1 PID: 3890 Comm: udevd Not tainted 5.4.0-rc3+ #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/0x10 kernel/kcsan/report.c:302
 __kcsan_setup_watchpoint+0x32e/0x4a0 kernel/kcsan/core.c:411
 __tsan_read8 kernel/kcsan/kcsan.c:36 [inline]
 __tsan_read8+0x2c/0x30 kernel/kcsan/kcsan.c:36
 relatime_need_update fs/inode.c:1633 [inline]
 atime_needs_update+0x264/0x360 fs/inode.c:1721
 touch_atime+0x63/0x190 fs/inode.c:1736
 do_readlinkat+0x1d8/0x220 fs/stat.c:410
 __do_sys_readlink fs/stat.c:432 [inline]
 __se_sys_readlink fs/stat.c:429 [inline]
 __x64_sys_readlink+0x51/0x70 fs/stat.c:429
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7f13e1a46577
Code: f0 ff ff 77 02 f3 c3 48 8b 15 bd 38 2b 00 f7 d8 64 89 02 83 c8 ff c3 90 90 90 90 90 90 90 90 90 90 90 90 b8 59 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 91 38 2b 00 31 d2 48 29 c2 64
RSP: 002b:00007ffc3320e538 EFLAGS: 00000202 ORIG_RAX: 0000000000000059
RAX: ffffffffffffffda RBX: 0000000000dd5250 RCX: 00007f13e1a46577
RDX: 00000000000003fc RSI: 00007ffc3320e964 RDI: 00007ffc3320e560
RBP: 00000000000003fc R08: 0000000000dd50d0 R09: 00007f13e1a9b1d0
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000003
R13: 0000000000000000 R14: 0000000000e05400 R15: 0000000000dd5250
Kernel Offset: disabled
Rebooting in 86400 seconds..