syzbot

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BUG: KCSAN: data-race in atime_needs_update / inode_update_timestamps

write to 0xffff888110ca9264 of 4 bytes by task 21041 on cpu 1:
 inode_set_mtime_to_ts include/linux/fs.h:1708 [inline]
 inode_update_timestamps+0x139/0x250 fs/inode.c:2070
 generic_update_time fs/inode.c:2105 [inline]
 inode_update_time fs/inode.c:2125 [inline]
 __file_update_time fs/inode.c:2353 [inline]
 file_update_time+0x219/0x2b0 fs/inode.c:2383
 shmem_file_write_iter+0x99/0xe0 mm/shmem.c:3474
 iter_file_splice_write+0x5f1/0x980 fs/splice.c:743
 do_splice_from fs/splice.c:941 [inline]
 direct_splice_actor+0x160/0x2c0 fs/splice.c:1164
 splice_direct_to_actor+0x302/0x670 fs/splice.c:1108
 do_splice_direct_actor fs/splice.c:1207 [inline]
 do_splice_direct+0xd7/0x150 fs/splice.c:1233
 do_sendfile+0x398/0x660 fs/read_write.c:1363
 __do_sys_sendfile64 fs/read_write.c:1424 [inline]
 __se_sys_sendfile64 fs/read_write.c:1410 [inline]
 __x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1410
 x64_sys_call+0xfbd/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888110ca9264 of 4 bytes by task 21037 on cpu 0:
 inode_get_mtime_nsec include/linux/fs.h:1694 [inline]
 inode_get_mtime include/linux/fs.h:1700 [inline]
 relatime_need_update fs/inode.c:2019 [inline]
 atime_needs_update+0x2aa/0x3e0 fs/inode.c:2165
 touch_atime+0x4a/0x350 fs/inode.c:2180
 file_accessed include/linux/fs.h:2601 [inline]
 shmem_file_splice_read+0x579/0x5d0 mm/shmem.c:3636
 do_splice_read fs/splice.c:985 [inline]
 splice_direct_to_actor+0x269/0x670 fs/splice.c:1089
 do_splice_direct_actor fs/splice.c:1207 [inline]
 do_splice_direct+0xd7/0x150 fs/splice.c:1233
 do_sendfile+0x398/0x660 fs/read_write.c:1363
 __do_sys_sendfile64 fs/read_write.c:1424 [inline]
 __se_sys_sendfile64 fs/read_write.c:1410 [inline]
 __x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1410
 x64_sys_call+0xfbd/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x2d1f0511 -> 0x2dadc020

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 21037 Comm: syz.5.5978 Not tainted 6.14.0-rc6-syzkaller-00103-g4003c9e78778 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
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