[moderation] [block?] KCSAN: data-race in loop_configure / shmem_write_begin (5)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 3ca112b71f35 Merge tag 'probes-fixes-v6.7-rc1' of git://gi..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=14b2822f680000
kernel config: https://syzkaller.appspot.com/x/.config?x=1c4caf9f31b81308
dashboard link: https://syzkaller.appspot.com/bug?extid=97ab1c55da48cee65f77
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/06b08cfc6edb/disk-3ca112b7.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/4015d21a3b25/vmlinux-3ca112b7.xz
kernel image: https://storage.googleapis.com/syzbot-assets/27b26ecfc1c5/bzImage-3ca112b7.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+97ab1c...@syzkaller.appspotmail.com

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

read-write to 0xffff888129bf13d8 of 4 bytes by task 32511 on cpu 1:
mapping_set_gfp_mask include/linux/pagemap.h:310 [inline]
loop_configure+0x7c0/0xca0 drivers/block/loop.c:1077
lo_ioctl+0x682/0x12e0
blkdev_ioctl+0x375/0x460 block/ioctl.c:633
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:51 [inline]
do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x63/0x6b

read to 0xffff888129bf13d8 of 4 bytes by task 32497 on cpu 0:
mapping_gfp_mask include/linux/pagemap.h:294 [inline]
shmem_get_folio mm/shmem.c:2120 [inline]
shmem_write_begin+0x84/0x1b0 mm/shmem.c:2702
generic_perform_write+0x1c9/0x410 mm/filemap.c:3918
shmem_file_write_iter+0xc8/0xe0 mm/shmem.c:2878
do_iter_write+0x4ad/0x770 fs/read_write.c:860
vfs_writev+0x1a8/0x320 fs/read_write.c:933
do_pwritev fs/read_write.c:1030 [inline]
__do_sys_pwritev fs/read_write.c:1077 [inline]
__se_sys_pwritev fs/read_write.c:1072 [inline]
__x64_sys_pwritev+0x100/0x1c0 fs/read_write.c:1072
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x00100cca -> 0x00100c0a

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 32497 Comm: syz-executor.3 Not tainted 6.6.0-syzkaller-16159-g3ca112b71f35 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/09/2023
==================================================================


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[syzbot]

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