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

write to 0xffff88810659aaa8 of 8 bytes by task 2740 on cpu 1:
 inode_set_mtime_to_ts include/linux/fs.h:1573 [inline]
 inode_update_timestamps+0x16f/0x280 fs/inode.c:1863
 generic_update_time fs/inode.c:1898 [inline]
 inode_update_time fs/inode.c:1918 [inline]
 __file_update_time fs/inode.c:2106 [inline]
 file_modified_flags+0x29c/0x330 fs/inode.c:2177
 file_modified+0x17/0x20 fs/inode.c:2193
 ext4_write_checks fs/ext4/file.c:279 [inline]
 ext4_buffered_write_iter+0x1d8/0x370 fs/ext4/file.c:295
 ext4_file_write_iter+0x297/0xe10
 __kernel_write_iter+0x25f/0x480 fs/read_write.c:523
 __kernel_write fs/read_write.c:543 [inline]
 kernel_write+0x1f3/0x400 fs/read_write.c:564
 p9_fd_write net/9p/trans_fd.c:433 [inline]
 p9_write_work+0x32a/0x740 net/9p/trans_fd.c:484
 process_one_work kernel/workqueue.c:2633 [inline]
 process_scheduled_works+0x5b8/0xa40 kernel/workqueue.c:2706
 worker_thread+0x525/0x730 kernel/workqueue.c:2787
 kthread+0x1d7/0x210 kernel/kthread.c:388
 ret_from_fork+0x48/0x60 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:243

read to 0xffff88810659aaa8 of 8 bytes by task 19169 on cpu 0:
 inode_get_mtime include/linux/fs.h:1567 [inline]
 relatime_need_update fs/inode.c:1812 [inline]
 atime_needs_update+0x2ce/0x3f0 fs/inode.c:1958
 touch_atime+0x4a/0x340 fs/inode.c:1973
 file_accessed include/linux/fs.h:2436 [inline]
 ext4_dio_read_iter fs/ext4/file.c:97 [inline]
 ext4_file_read_iter+0x271/0x2a0 fs/ext4/file.c:145
 call_read_iter include/linux/fs.h:2081 [inline]
 copy_splice_read+0x39f/0x5d0 fs/splice.c:365
 do_splice_read fs/splice.c:984 [inline]
 splice_direct_to_actor+0x288/0x660 fs/splice.c:1089
 do_splice_direct_actor fs/splice.c:1207 [inline]
 do_splice_direct+0xd7/0x150 fs/splice.c:1233
 do_sendfile+0x3b9/0x960 fs/read_write.c:1295
 __do_sys_sendfile64 fs/read_write.c:1362 [inline]
 __se_sys_sendfile64 fs/read_write.c:1348 [inline]
 __x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1348
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x00000000307a57ea -> 0x000000003112ee6a

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 19169 Comm: syz-executor.4 Not tainted 6.8.0-rc7-syzkaller-00051-g67be068d31d4 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024
==================================================================