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Date:   Mon, 11 Jul 2022 21:46:59 +0100
From:   Matthew Wilcox <willy@infradead.org>
To:     Andrew Morton <akpm@linux-foundation.org>
Cc:     syzbot <syzbot+a785d07959bc94837d51@syzkaller.appspotmail.com>,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        syzkaller-bugs@googlegroups.com, Zach O'Keefe <zokeefe@google.com>,
        Yang Shi <shy828301@gmail.com>,
        Liam Howlett <liam.howlett@oracle.com>
Subject: Re: [syzbot] memory leak in xas_create
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 <20220711133808.d86400ce9960febcb0fd537b@linux-foundation.org>
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On Mon, Jul 11, 2022 at 01:38:08PM -0700, Andrew Morton wrote:
> On Sat, 09 Jul 2022 00:13:23 -0700 syzbot <syzbot+a785d07959bc94837d51@syzkaller.appspotmail.com> wrote:
> 
> > Hello,
> > 
> > syzbot found the following issue on:
> > 
> > HEAD commit:    c1084b6c5620 Merge tag 'soc-fixes-5.19-2' of git://git.ker..
> > git tree:       upstream
> > console output: https://syzkaller.appspot.com/x/log.txt?x=14967ccc080000
> > kernel config:  https://syzkaller.appspot.com/x/.config?x=916233b7694a38ff
> > dashboard link: https://syzkaller.appspot.com/bug?extid=a785d07959bc94837d51
> > compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
> > syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=122ae834080000
> > 
> > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > Reported-by: syzbot+a785d07959bc94837d51@syzkaller.appspotmail.com
> > 
> > 2022/07/05 05:22:17 executed programs: 828
> > 2022/07/05 05:22:23 executed programs: 846
> > 2022/07/05 05:22:30 executed programs: 866
> > 2022/07/05 05:22:37 executed programs: 875
> > BUG: memory leak
> 
> Thanks.  Presumably due to khugepaged changes.

Huh, I was expecting it to be something I'd messed up.  I've been
looking at it today, but no luck figuring it out so far.

> Can we expect a bisection search?

We only have a syz reproducer so far, and if I understand correctly,
it's probably because this is a flaky test (because it's trying to
find something that's a race condition).

I expect a bisection search to go badly wrong if this is true.