syzbot

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BUG: KCSAN: data-race in atime_needs_update / propagate_mnt

write to 0xffff88812a8d15f0 of 4 bytes by task 19662 on cpu 0:
 propagate_mnt+0x5e8/0x640 fs/pnode.c:330
 attach_recursive_mnt+0x519/0x1210 fs/namespace.c:2129
 graft_tree fs/namespace.c:2237 [inline]
 do_add_mount fs/namespace.c:2784 [inline]
 do_new_mount_fc fs/namespace.c:2823 [inline]
 do_new_mount fs/namespace.c:2877 [inline]
 path_mount+0x1b49/0x1c70 fs/namespace.c:3192
 do_mount fs/namespace.c:3205 [inline]
 __do_sys_mount fs/namespace.c:3413 [inline]
 __se_sys_mount+0x126/0x180 fs/namespace.c:3390
 __x64_sys_mount+0x63/0x70 fs/namespace.c:3390
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88812a8d15f0 of 4 bytes by task 19664 on cpu 1:
 atime_needs_update+0x133/0x370 fs/inode.c:1806
 touch_atime+0x53/0x1a0 fs/inode.c:1828
 file_accessed include/linux/fs.h:2193 [inline]
 generic_file_buffered_read+0x1c29/0x1cf0 mm/filemap.c:2328
 generic_file_read_iter+0x7d/0x3e0 mm/filemap.c:2405
 ext4_file_read_iter+0x2d8/0x420 fs/ext4/file.c:74
 call_read_iter include/linux/fs.h:1866 [inline]
 new_sync_read fs/read_write.c:415 [inline]
 __kernel_read+0x3cf/0x600 fs/read_write.c:438
 kernel_read+0x58/0x70 fs/read_write.c:457
 elf_read fs/binfmt_elf.c:417 [inline]
 load_elf_binary+0x164f/0x2eb0 fs/binfmt_elf.c:890
 search_binary_handler fs/exec.c:1809 [inline]
 exec_binprm+0x1d9/0x760 fs/exec.c:1850
 bprm_execve+0x42d/0x610 fs/exec.c:1921
 kernel_execve+0x60b/0x640 fs/exec.c:2070
 call_usermodehelper_exec_async+0x17e/0x230 kernel/umh.c:101
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 19664 Comm: kworker/u4:3 Not tainted 5.8.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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