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

write to 0xffff8881298d61d0 of 16 bytes by task 4877 on cpu 1:
 generic_update_time+0x109/0x270 fs/inode.c:1674
 update_time+0x85/0x90 fs/inode.c:1694
 file_update_time+0x205/0x2d0 fs/inode.c:1909
 file_modified fs/inode.c:1932 [inline]
 file_modified+0x65/0x80 fs/inode.c:1917
 ext4_dio_write_checks fs/ext4/file.c:430 [inline]
 ext4_dio_write_iter fs/ext4/file.c:494 [inline]
 ext4_file_write_iter+0xb73/0xd70 fs/ext4/file.c:640
 call_write_iter include/linux/fs.h:1901 [inline]
 do_iter_readv_writev+0x487/0x5b0 fs/read_write.c:693
 do_iter_write fs/read_write.c:998 [inline]
 do_iter_write+0x13b/0x3c0 fs/read_write.c:979
 vfs_iter_write+0x5c/0x80 fs/read_write.c:1039
 iter_file_splice_write+0x536/0x850 fs/splice.c:760
 do_splice_from fs/splice.c:863 [inline]
 direct_splice_actor+0xa0/0xc0 fs/splice.c:1037
 splice_direct_to_actor+0x22b/0x540 fs/splice.c:992
 do_splice_direct+0x161/0x1e0 fs/splice.c:1080
 do_sendfile+0x384/0x7f0 fs/read_write.c:1520
 __do_sys_sendfile64 fs/read_write.c:1581 [inline]
 __se_sys_sendfile64 fs/read_write.c:1567 [inline]
 __x64_sys_sendfile64+0x12a/0x140 fs/read_write.c:1567
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff8881298d61d8 of 8 bytes by task 4944 on cpu 0:
 timespec64_compare include/linux/time64.h:66 [inline]
 relatime_need_update fs/inode.c:1642 [inline]
 atime_needs_update+0x232/0x360 fs/inode.c:1732
 touch_atime+0x63/0x150 fs/inode.c:1747
 file_accessed include/linux/fs.h:2220 [inline]
 generic_file_splice_read+0x4e7/0x500 fs/splice.c:316
 do_splice_to+0xf2/0x130 fs/splice.c:892
 splice_direct_to_actor+0x1b6/0x540 fs/splice.c:971
 do_splice_direct+0x161/0x1e0 fs/splice.c:1080
 do_sendfile+0x384/0x7f0 fs/read_write.c:1520
 __do_sys_sendfile64 fs/read_write.c:1581 [inline]
 __se_sys_sendfile64 fs/read_write.c:1567 [inline]
 __x64_sys_sendfile64+0x12a/0x140 fs/read_write.c:1567
 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: 4944 Comm: syz-executor.0 Not tainted 5.6.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================