[moderation] [ext4?] KCSAN: data-race in atime_needs_update / inode_update_timestamps

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 9ace34a8e446 Merge tag 'cgroup-for-6.7-rc4-fixes' of git:/..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=148a78dae80000
kernel config: https://syzkaller.appspot.com/x/.config?x=ac34c1f29a8029df
dashboard link: https://syzkaller.appspot.com/bug?extid=874bb8a8db3b21a66b1c
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/955528ed37c5/disk-9ace34a8.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/ed03c0892611/vmlinux-9ace34a8.xz
kernel image: https://storage.googleapis.com/syzbot-assets/b4d56563956a/bzImage-9ace34a8.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+874bb8...@syzkaller.appspotmail.com

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

write to 0xffff8881076b73b8 of 8 bytes by task 3852 on cpu 0:
inode_set_atime_to_ts include/linux/fs.h:1537 [inline]
inode_update_timestamps+0x4d1/0x560 fs/inode.c:1914
generic_update_time fs/inode.c:1936 [inline]
inode_update_time fs/inode.c:1956 [inline]
touch_atime+0x15c/0x2d0 fs/inode.c:2028
file_accessed include/linux/fs.h:2360 [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:2014 [inline]
copy_splice_read+0x26b/0x4b0 fs/splice.c:364
vfs_splice_read fs/splice.c:992 [inline]
splice_direct_to_actor+0x2aa/0x690 fs/splice.c:1069
do_splice_direct+0x10d/0x190 fs/splice.c:1194
do_sendfile+0x3c4/0x980 fs/read_write.c:1254
__do_sys_sendfile64 fs/read_write.c:1322 [inline]
__se_sys_sendfile64 fs/read_write.c:1308 [inline]
__x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1308
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x63/0x6b

read to 0xffff8881076b73b8 of 8 bytes by task 3854 on cpu 1:
atime_needs_update+0x3cf/0x550
touch_atime+0x46/0x2d0 fs/inode.c:2011
file_accessed include/linux/fs.h:2360 [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:2014 [inline]
copy_splice_read+0x26b/0x4b0 fs/splice.c:364
vfs_splice_read fs/splice.c:992 [inline]
splice_direct_to_actor+0x2aa/0x690 fs/splice.c:1069
do_splice_direct+0x10d/0x190 fs/splice.c:1194
do_sendfile+0x3c4/0x980 fs/read_write.c:1254
__do_sys_sendfile64 fs/read_write.c:1322 [inline]
__se_sys_sendfile64 fs/read_write.c:1308 [inline]
__x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1308
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x0000000022aa9298 -> 0x0000000023dbbf98

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 3854 Comm: syz-executor.3 Not tainted 6.7.0-rc4-syzkaller-00039-g9ace34a8e446 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/10/2023
==================================================================


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