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BUG: KCSAN: data-race in atime_needs_update / inode_update_timestamps

write to 0xffff8881054033c8 of 8 bytes by task 12804 on cpu 1:
 inode_set_mtime_to_ts include/linux/fs.h:1571 [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
 call_write_iter include/linux/fs.h:2085 [inline]
 iter_file_splice_write+0x5de/0x950 fs/splice.c:743
 do_splice_from fs/splice.c:941 [inline]
 direct_splice_actor+0x167/0x2c0 fs/splice.c:1164
 splice_direct_to_actor+0x2fb/0x660 fs/splice.c:1108
 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:1356 [inline]
 __se_sys_sendfile64 fs/read_write.c:1348 [inline]
 __x64_sys_sendfile64+0xbd/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

read to 0xffff8881054033c8 of 8 bytes by task 12750 on cpu 0:
 inode_get_mtime include/linux/fs.h:1565 [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:2437 [inline]
 filemap_splice_read+0x837/0x8f0 mm/filemap.c:2928
 ext4_file_splice_read+0x95/0xb0 fs/ext4/file.c:158
 do_splice_read fs/splice.c:985 [inline]
 splice_direct_to_actor+0x268/0x660 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:1356 [inline]
 __se_sys_sendfile64 fs/read_write.c:1348 [inline]
 __x64_sys_sendfile64+0xbd/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: 0x000000000342bb97 -> 0x0000000003db5217

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 12750 Comm: syz-executor.4 Not tainted 6.8.0-rc3-syzkaller-00317-g7521f258ea30 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024
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