[moderation] [mm?] KCSAN: data-race in generic_fillattr / shmem_symlink (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: afcd48134c58 Merge tag 'mm-hotfixes-stable-2024-06-26-17-2..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=157e783a980000
kernel config: https://syzkaller.appspot.com/x/.config?x=7e87b541dc1fc960
dashboard link: https://syzkaller.appspot.com/bug?extid=e4b2def43a75c1357c73
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/74d7d3ec21bb/disk-afcd4813.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/fd49a4ae8fb1/vmlinux-afcd4813.xz
kernel image: https://storage.googleapis.com/syzbot-assets/57af65bdecc0/bzImage-afcd4813.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+e4b2de...@syzkaller.appspotmail.com

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

write to 0xffff888103ff3bb0 of 8 bytes by task 3070 on cpu 1:
inode_set_mtime_to_ts include/linux/fs.h:1587 [inline]
shmem_symlink+0x349/0x3a0 mm/shmem.c:3540
vfs_symlink+0xca/0x1d0 fs/namei.c:4489
do_symlinkat+0xe3/0x350 fs/namei.c:4515
__do_sys_symlink fs/namei.c:4536 [inline]
__se_sys_symlink fs/namei.c:4534 [inline]
__x64_sys_symlink+0x56/0x70 fs/namei.c:4534
x64_sys_call+0x14d2/0x2d70 arch/x86/include/generated/asm/syscalls_64.h:89
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 0xffff888103ff3bb0 of 8 bytes by task 3156 on cpu 0:
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: 0x0000000025ea3ce7 -> 0x000000002682d367

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 3156 Comm: udevd Not tainted 6.10.0-rc5-syzkaller-00035-gafcd48134c58 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
==================================================================


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