[moderation] [mm?] KCSAN: data-race in generic_fillattr / shmem_unlink (4)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 7c16f0a4ed1c Merge tag 'i2c-for-6.10-rc5' of git://git.ker..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1257939c980000
kernel config: https://syzkaller.appspot.com/x/.config?x=704451bc2941bcb0
dashboard link: https://syzkaller.appspot.com/bug?extid=58bc3169b550bf7ad5d5
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
CC: [ak...@linux-foundation.org hu...@google.com linux-...@vger.kernel.org linu...@kvack.org]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/9acd4869df3e/disk-7c16f0a4.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/a5b6e853a6e5/vmlinux-7c16f0a4.xz
kernel image: https://storage.googleapis.com/syzbot-assets/23b225386827/bzImage-7c16f0a4.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+58bc31...@syzkaller.appspotmail.com

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

write to 0xffff88810423ad00 of 8 bytes by task 3074 on cpu 0:
inode_set_mtime_to_ts include/linux/fs.h:1587 [inline]
shmem_unlink+0x150/0x190 mm/shmem.c:3393
vfs_unlink+0x275/0x430 fs/namei.c:4343
do_unlinkat+0x236/0x4c0 fs/namei.c:4407
__do_sys_unlink fs/namei.c:4455 [inline]
__se_sys_unlink fs/namei.c:4453 [inline]
__x64_sys_unlink+0x30/0x40 fs/namei.c:4453
x64_sys_call+0x28a3/0x2d70 arch/x86/include/generated/asm/syscalls_64.h:88
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 0xffff88810423ad00 of 8 bytes by task 3091 on cpu 1:
inode_get_mtime include/linux/fs.h:1581 [inline]
generic_fillattr+0x1a6/0x2f0 fs/stat.c:61
shmem_getattr+0x17b/0x200 mm/shmem.c:1139
vfs_getattr_nosec fs/stat.c:135 [inline]
vfs_getattr+0x19b/0x1e0 fs/stat.c:176
vfs_statx+0x140/0x320 fs/stat.c:248
vfs_fstatat+0xcd/0x100 fs/stat.c:304
__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

value changed: 0x0000000029b092bf -> 0x000000002a49293f

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 3091 Comm: udevd Not tainted 6.10.0-rc4-syzkaller-00330-g7c16f0a4ed1c #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
==================================================================


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