syzbot

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BUG: KCSAN: data-race in atime_needs_update / ext4_remount

read to 0xffff88812b3cd050 of 8 bytes by task 7807 on cpu 1:
 atime_needs_update+0xb3/0x360 fs/inode.c:1709
 touch_atime+0x63/0x190 fs/inode.c:1736
 get_link fs/namei.c:1058 [inline]
 trailing_symlink+0x1be/0x5b0 fs/namei.c:2250
 path_mountpoint+0x651/0xdb0 fs/namei.c:2703
 filename_mountpoint+0x134/0x270 fs/namei.c:2724
 user_path_mountpoint_at+0x43/0x60 fs/namei.c:2754
 ksys_umount+0xdb/0xab0 fs/namespace.c:1683
 __do_sys_umount fs/namespace.c:1709 [inline]
 __se_sys_umount fs/namespace.c:1707 [inline]
 __x64_sys_umount+0x3a/0x50 fs/namespace.c:1707
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

write to 0xffff88812b3cd050 of 8 bytes by task 18860 on cpu 0:
 ext4_remount+0x685/0x13a0 fs/ext4/super.c:5361
 legacy_reconfigure+0x9a/0xc0 fs/fs_context.c:670
 reconfigure_super+0x36a/0x570 fs/super.c:955
 do_remount fs/namespace.c:2553 [inline]
 do_mount+0x1136/0x14f0 fs/namespace.c:3133
 ksys_mount+0xe8/0x160 fs/namespace.c:3351
 __do_sys_mount fs/namespace.c:3365 [inline]
 __se_sys_mount fs/namespace.c:3362 [inline]
 __x64_sys_mount+0x70/0x90 fs/namespace.c:3362
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 18860 Comm: syz-executor.5 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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