[moderation] [ext4?] KCSAN: data-race in atime_needs_update / touch_atime (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 5c24e4e9e708 Merge tag 'hid-for-linus-2024020101' of git:/..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16a774b7e80000
kernel config: https://syzkaller.appspot.com/x/.config?x=4aab723d3dfffc44
dashboard link: https://syzkaller.appspot.com/bug?extid=22e9f4940fef7f9a657a
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
CC: [adilger...@dilger.ca linux...@vger.kernel.org linux-...@vger.kernel.org linux-...@vger.kernel.org ty...@mit.edu]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/939a791831ca/disk-5c24e4e9.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/0ffa996f3841/vmlinux-5c24e4e9.xz
kernel image: https://storage.googleapis.com/syzbot-assets/00a87458e25f/bzImage-5c24e4e9.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+22e9f4...@syzkaller.appspotmail.com

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

write to 0xffff888107eb4aa8 of 8 bytes by task 6904 on cpu 1:
inode_set_atime_to_ts include/linux/fs.h:1541 [inline]
inode_update_timestamps fs/inode.c:1876 [inline]
generic_update_time fs/inode.c:1898 [inline]
inode_update_time fs/inode.c:1918 [inline]
touch_atime+0x1ed/0x340 fs/inode.c:1990
file_accessed include/linux/fs.h:2437 [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:2079 [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

read to 0xffff888107eb4aa8 of 8 bytes by task 6905 on cpu 0:
atime_needs_update+0x264/0x3f0
touch_atime+0x4a/0x340 fs/inode.c:1973
file_accessed include/linux/fs.h:2437 [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:2079 [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: 0x000000001111a399 -> 0x0000000011aa3a19

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 6905 Comm: syz-executor.1 Not tainted 6.8.0-rc2-syzkaller-00084-g5c24e4e9e708 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024
==================================================================


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