[moderation] [block?] KCSAN: data-race in __kernel_write_iter / set_task_ioprio (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 8477ab143069 Merge tag 'iommu-updates-v6.16' of git://git...
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=178f0ff4580000
kernel config: https://syzkaller.appspot.com/x/.config?x=bfd0efda7515506a
dashboard link: https://syzkaller.appspot.com/bug?extid=33b1124e997e5f0d7303
compiler: Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6
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/409c4f3694c7/disk-8477ab14.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/17ec9f446100/vmlinux-8477ab14.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c1f7aba70548/bzImage-8477ab14.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+33b112...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in __kernel_write_iter / set_task_ioprio

write to 0xffff8881009d6a48 of 8 bytes by task 4808 on cpu 0:
set_task_ioprio+0x24f/0x270 block/blk-ioc.c:280
__do_sys_ioprio_set block/ioprio.c:121 [inline]
__se_sys_ioprio_set+0x250/0x5a0 block/ioprio.c:65
__x64_sys_ioprio_set+0x43/0x50 block/ioprio.c:65
x64_sys_call+0x1982/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:252
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff8881009d6a48 of 8 bytes by task 4779 on cpu 1:
__get_task_ioprio include/linux/ioprio.h:59 [inline]
get_current_ioprio include/linux/ioprio.h:83 [inline]
init_sync_kiocb include/linux/fs.h:2441 [inline]
__kernel_write_iter+0xdc/0x4c0 fs/read_write.c:617
dump_emit_page fs/coredump.c:1112 [inline]
dump_user_range+0x407/0x8c0 fs/coredump.c:1186
elf_core_dump+0x1dc2/0x1f80 fs/binfmt_elf.c:2075
do_coredump+0x1dfd/0x27b0 fs/coredump.c:950
get_signal+0xd85/0xf70 kernel/signal.c:3019
arch_do_signal_or_restart+0x96/0x480 arch/x86/kernel/signal.c:337
exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
exit_to_user_mode_prepare include/linux/entry-common.h:330 [inline]
irqentry_exit_to_user_mode+0x5e/0xa0 kernel/entry/common.c:184
irqentry_exit+0x12/0x50 kernel/entry/common.c:287
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623

value changed: 0x0000000000000000 -> 0xffff8881016dc660

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 4779 Comm: +}[@ Not tainted 6.15.0-syzkaller-09113-g8477ab143069 #0 PREEMPT(voluntary)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
==================================================================


---
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

[syzbot]

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