[moderation] [fs?] KCSAN: data-race in generic_fillattr / touch_atime (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: cea2a26553ac mailmap: Add my outdated addresses to the map..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1359276a980000
kernel config: https://syzkaller.appspot.com/x/.config?x=68336ea4b6f4fc09
dashboard link: https://syzkaller.appspot.com/bug?extid=133d4110384cf842ed62
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
CC: [bra...@kernel.org ja...@suse.cz linux-...@vger.kernel.org linux-...@vger.kernel.org vi...@zeniv.linux.org.uk]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/ef5182d10059/disk-cea2a265.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/8d67ce032aec/vmlinux-cea2a265.xz
kernel image: https://storage.googleapis.com/syzbot-assets/78178b59b689/bzImage-cea2a265.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+133d41...@syzkaller.appspotmail.com

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

write to 0xffff8881189403d0 of 8 bytes by task 3089 on cpu 0:
inode_set_atime_to_ts include/linux/fs.h:1557 [inline]
inode_update_timestamps fs/inode.c:1878 [inline]
generic_update_time fs/inode.c:1900 [inline]
inode_update_time fs/inode.c:1920 [inline]
touch_atime+0x1f3/0x350 fs/inode.c:1992
file_accessed include/linux/fs.h:2458 [inline]
shmem_file_read_iter+0x4b3/0x550 mm/shmem.c:2899
new_sync_read fs/read_write.c:395 [inline]
vfs_read+0x5e6/0x6e0 fs/read_write.c:476
ksys_read+0xeb/0x1b0 fs/read_write.c:619
__do_sys_read fs/read_write.c:629 [inline]
__se_sys_read fs/read_write.c:627 [inline]
__x64_sys_read+0x42/0x50 fs/read_write.c:627
x64_sys_call+0x27e5/0x2d70 arch/x86/include/generated/asm/syscalls_64.h:1
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 0xffff8881189403d0 of 8 bytes by task 3010 on cpu 1:
inode_get_atime include/linux/fs.h:1551 [inline]
generic_fillattr+0x16f/0x2f0 fs/stat.c:60
shmem_getattr+0x17b/0x200 mm/shmem.c:1139
vfs_getattr_nosec fs/stat.c:135 [inline]
vfs_getattr fs/stat.c:176 [inline]
vfs_fstat+0x1b9/0x470 fs/stat.c:198
vfs_fstatat+0x85/0x100 fs/stat.c:300
__do_sys_newfstatat fs/stat.c:468 [inline]
__se_sys_newfstatat+0x58/0x260 fs/stat.c:462
__x64_sys_newfstatat+0x55/0x70 fs/stat.c:462
x64_sys_call+0x1451/0x2d70 arch/x86/include/generated/asm/syscalls_64.h:263
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



---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup