[moderation] [block?] KCSAN: data-race in loop_configure / shmem_write_begin (6)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 3a5879d495b2 Merge tag 'ata-6.8-rc2' of git://git.kernel.o..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17eb8ea0180000
kernel config: https://syzkaller.appspot.com/x/.config?x=e1bd33f45956bbc2
dashboard link: https://syzkaller.appspot.com/bug?extid=eac05ae4e92a7e87b398
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
CC: [ax...@kernel.dk linux...@vger.kernel.org linux-...@vger.kernel.org]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/a96be9241f44/disk-3a5879d4.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/386c65ac5e13/vmlinux-3a5879d4.xz
kernel image: https://storage.googleapis.com/syzbot-assets/0edb10e21dd1/bzImage-3a5879d4.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+eac05a...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in loop_configure / shmem_write_begin

read-write to 0xffff88811af7c528 of 4 bytes by task 29422 on cpu 0:
mapping_set_gfp_mask include/linux/pagemap.h:344 [inline]
loop_configure+0x7c0/0xca0 drivers/block/loop.c:1073
lo_ioctl+0x682/0x12e0
blkdev_ioctl+0x375/0x460 block/ioctl.c:634
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:871 [inline]
__se_sys_ioctl+0xcf/0x140 fs/ioctl.c:857
__x64_sys_ioctl+0x43/0x50 fs/ioctl.c:857
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0x59/0x120 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x63/0x6b

read to 0xffff88811af7c528 of 4 bytes by task 29410 on cpu 1:
mapping_gfp_mask include/linux/pagemap.h:328 [inline]
shmem_get_folio mm/shmem.c:2135 [inline]
shmem_write_begin+0x84/0x1b0 mm/shmem.c:2717
generic_perform_write+0x1c9/0x410 mm/filemap.c:3930
shmem_file_write_iter+0xc8/0xe0 mm/shmem.c:2893
call_write_iter include/linux/fs.h:2085 [inline]
new_sync_write fs/read_write.c:497 [inline]
vfs_write+0x760/0x8d0 fs/read_write.c:590
ksys_write+0xeb/0x1a0 fs/read_write.c:643
__do_sys_write fs/read_write.c:655 [inline]
__se_sys_write fs/read_write.c:652 [inline]
__x64_sys_write+0x42/0x50 fs/read_write.c:652
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0x59/0x120 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x00100cca -> 0x00100c0a

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 29410 Comm: syz-executor.1 Not tainted 6.8.0-rc1-syzkaller-00311-g3a5879d495b2 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023
==================================================================


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.