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

read to 0xffff8881245dd138 of 8 bytes by task 3889 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

write to 0xffff8881245dd138 of 16 bytes by task 7174 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

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 7174 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: 0 PID: 7174 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_write16 kernel/kcsan/kcsan.c:37 [inline]
 __tsan_write16+0x32/0x40 kernel/kcsan/kcsan.c:37
 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
RIP: 0033:0x7f162b3855d7
Code: 48 3d 00 f0 ff ff 77 03 48 98 c3 48 8b 15 59 38 2b 00 f7 d8 64 89 02 48 83 c8 ff c3 90 90 90 90 90 90 90 b8 57 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 31 38 2b 00 31 d2 48 29 c2 64
RSP: 002b:00007fff875f2ec8 EFLAGS: 00000206 ORIG_RAX: 0000000000000057
RAX: ffffffffffffffda RBX: 00000000016466d0 RCX: 00007f162b3855d7
RDX: 00007fff875f2ef5 RSI: 000000000041cce6 RDI: 00007fff875f2ee0
RBP: 000000000162d250 R08: 0000000000000000 R09: 0000000000000001
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000004450
R13: 0000000000625500 R14: 000000000162d250 R15: 000000000000000b
Kernel Offset: disabled
Rebooting in 86400 seconds..