On 8/13/24 2:50 AM, syzbot wrote: > Hello, > > syzbot found the following issue on: > > HEAD commit: 6a0e38264012 Merge tag 'for-6.11-rc2-tag' of git://git.ker.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=1019759d980000 > kernel config: https://syzkaller.appspot.com/x/.config?x=cb57e6ebf675f9d2 > dashboard link: https://syzkaller.appspot.com/bug?extid=2b946a3fd80caf971b21 > compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40 > > Unfortunately, I don't have any reproducer for this issue yet. > > Downloadable assets: > disk image: https://storage.googleapis.com/syzbot-assets/753a842a966b/disk-6a0e3826.raw.xz > vmlinux: https://storage.googleapis.com/syzbot-assets/e12e23519777/vmlinux-6a0e3826.xz > kernel image: https://storage.googleapis.com/syzbot-assets/bce0584a8cb4/bzImage-6a0e3826.xz > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+2b946a3fd80caf971b21@xxxxxxxxxxxxxxxxxxxxxxxxx > > ================================================================== > BUG: KCSAN: data-race in io_sq_thread / io_sq_thread_park > > write to 0xffff888111459638 of 8 bytes by task 10761 on cpu 1: > io_sq_thread+0xdab/0xff0 io_uring/sqpoll.c:383 > ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:147 > ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 > > read to 0xffff888111459638 of 8 bytes by task 10329 on cpu 0: > io_sq_thread_park+0x1b/0x80 io_uring/sqpoll.c:47 > io_ring_exit_work+0x197/0x500 io_uring/io_uring.c:2786 > process_one_work kernel/workqueue.c:3231 [inline] > process_scheduled_works+0x483/0x9a0 kernel/workqueue.c:3312 > worker_thread+0x526/0x700 kernel/workqueue.c:3390 > kthread+0x1d1/0x210 kernel/kthread.c:389 > ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:147 > ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 > > value changed: 0xffff8881223d0000 -> 0x0000000000000000 It's just a debug check. #syz test diff --git a/io_uring/sqpoll.c b/io_uring/sqpoll.c index b3722e5275e7..3b50dc9586d1 100644 --- a/io_uring/sqpoll.c +++ b/io_uring/sqpoll.c @@ -44,7 +44,7 @@ void io_sq_thread_unpark(struct io_sq_data *sqd) void io_sq_thread_park(struct io_sq_data *sqd) __acquires(&sqd->lock) { - WARN_ON_ONCE(sqd->thread == current); + WARN_ON_ONCE(data_race(sqd->thread) == current); atomic_inc(&sqd->park_pending); set_bit(IO_SQ_THREAD_SHOULD_PARK, &sqd->state); -- Jens Axboe
