Hi Bart and Christoph, On Mon, Feb 04, 2019 at 06:03:04PM -0800, syzbot wrote: > Hello, > > syzbot found the following crash on: > > HEAD commit: 5eeb63359b1e Merge tag 'for-linus' of git://git.kernel.org.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=17906f64c00000 > kernel config: https://syzkaller.appspot.com/x/.config?x=2e0064f906afee10 > dashboard link: https://syzkaller.appspot.com/bug?extid=a3accb352f9c22041cfa > compiler: gcc (GCC) 9.0.0 20181231 (experimental) > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=156479f8c00000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=128c75c4c00000 > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > Reported-by: syzbot+a3accb352f9c22041cfa@xxxxxxxxxxxxxxxxxxxxxxxxx > > ===================================================== > WARNING: SOFTIRQ-safe -> SOFTIRQ-unsafe lock order detected > 5.0.0-rc4+ #56 Not tainted > ----------------------------------------------------- > syz-executor263/8874 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire: > 00000000c469f622 (&ctx->fd_wqh){....}, at: spin_lock > include/linux/spinlock.h:329 [inline] > 00000000c469f622 (&ctx->fd_wqh){....}, at: aio_poll fs/aio.c:1772 [inline] > 00000000c469f622 (&ctx->fd_wqh){....}, at: __io_submit_one fs/aio.c:1875 > [inline] > 00000000c469f622 (&ctx->fd_wqh){....}, at: io_submit_one+0xedf/0x1cf0 > fs/aio.c:1908 > > and this task is already holding: > 00000000829de875 (&(&ctx->ctx_lock)->rlock){..-.}, at: spin_lock_irq > include/linux/spinlock.h:354 [inline] > 00000000829de875 (&(&ctx->ctx_lock)->rlock){..-.}, at: aio_poll > fs/aio.c:1771 [inline] > 00000000829de875 (&(&ctx->ctx_lock)->rlock){..-.}, at: __io_submit_one > fs/aio.c:1875 [inline] > 00000000829de875 (&(&ctx->ctx_lock)->rlock){..-.}, at: > io_submit_one+0xeb6/0x1cf0 fs/aio.c:1908 > which would create a new lock dependency: > (&(&ctx->ctx_lock)->rlock){..-.} -> (&ctx->fd_wqh){....} > This is still happening. See https://syzkaller.appspot.com/text?tag=CrashReport&x=129eb971a00000 for a report on Linus' tree from 5 days ago. I see that a few months ago there was a commit commit d3d6a18d7d351cbcc9b33dbedf710e65f8ce1595 Author: Bart Van Assche <bvanassche@xxxxxxx> Date: Fri Feb 8 16:59:49 2019 -0800 aio: Fix locking in aio_poll() but apparently it didn't fully fix the problem. - Eric
