From: Matthew Wilcox <willy@infradead.org>
To: Jann Horn <jannh@google.com>
Cc: syzbot <syzbot+cc36d44ec9f368e443d3@syzkaller.appspotmail.com>,
asml.silence@gmail.com, axboe@kernel.dk,
io-uring@vger.kernel.org, linux-kernel@vger.kernel.org,
syzkaller-bugs@googlegroups.com,
linux-fsdevel <linux-fsdevel@vger.kernel.org>
Subject: Re: [syzbot] [io-uring?] WARNING in __io_uring_free
Date: Thu, 28 Nov 2024 23:57:14 +0000 [thread overview]
Message-ID: <Z0kDWtjmlI_LwP5S@casper.infradead.org> (raw)
In-Reply-To: <CAG48ez0uhdGNCopX2nspLzWZKfuZp0XLyUk90kYku=sP7wsWfg@mail.gmail.com>
On Fri, Nov 29, 2024 at 12:30:35AM +0100, Jann Horn wrote:
> > ------------[ cut here ]------------
> > WARNING: CPU: 0 PID: 16 at io_uring/tctx.c:51 __io_uring_free+0xfa/0x140 io_uring/tctx.c:51
>
> This warning is a check for WARN_ON_ONCE(!xa_empty(&tctx->xa)); and as
> Jens pointed out, this was triggered after error injection caused a
> memory allocation inside xa_store() to fail.
>
> Is there maybe an issue where xa_store() can fail midway through while
> allocating memory for the xarray, so that xa_empty() is no longer true
> even though there is nothing in the xarray? (And if yes, is that
> working as intended?)
Yes, that's a known possibility. We have similar problems when people
use error injection with mapping->i_pages. The effort to fix it seems
disproportionate to the severity of the problem.
next prev parent reply other threads:[~2024-11-28 23:57 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-11-19 4:38 [syzbot] [io-uring?] WARNING in __io_uring_free syzbot
2024-11-20 2:09 ` Jens Axboe
2024-11-28 23:30 ` Jann Horn
2024-11-28 23:57 ` Matthew Wilcox [this message]
2024-11-29 14:17 ` Jens Axboe
2024-12-29 19:42 ` Fedor Pchelkin
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