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From:   Yu Zhao <yuzhao@google.com>
Date:   Wed, 15 Jun 2022 13:05:24 -0600
Message-ID: <CAOUHufY5dBrNc81oDnmKSyRY2d3=e0CZJiXaOUBs=LFoUBDJUg@mail.gmail.com>
Subject: Re: [PATCH v9 28/69] mm/mmap: reorganize munmap to use maple states
To:     Liam Howlett <liam.howlett@oracle.com>
Cc:     Qian Cai <quic_qiancai@quicinc.com>,
        "maple-tree@lists.infradead.org" <maple-tree@lists.infradead.org>,
        "linux-mm@kvack.org" <linux-mm@kvack.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>
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On Wed, Jun 15, 2022 at 12:55 PM Liam Howlett <liam.howlett@oracle.com> wrote:
>
> * Yu Zhao <yuzhao@google.com> [220615 14:08]:
> > On Wed, Jun 15, 2022 at 8:25 AM Liam Howlett <liam.howlett@oracle.com> wrote:
> > >
> > > * Yu Zhao <yuzhao@google.com> [220611 17:50]:
> > > > On Sat, Jun 11, 2022 at 2:11 PM Yu Zhao <yuzhao@google.com> wrote:
> > > > >
> > > > > On Mon, Jun 6, 2022 at 10:40 AM Qian Cai <quic_qiancai@quicinc.com> wrote:
> > > > > >
> > > > > > On Mon, Jun 06, 2022 at 04:19:52PM +0000, Liam Howlett wrote:
> > > > > > > Does your syscall fuzzer create a reproducer?  This looks like arm64
> > > > > > > and says 5.18.0-next-20220603 again.  Was this bisected to the patch
> > > > > > > above?
> > > > > >
> > > > > > This was triggered by running the fuzzer over the weekend.
> > > > > >
> > > > > > $ trinity -C 160
> > > > > >
> > > > > > No bisection was done. It was only brought up here because the trace
> > > > > > pointed to do_mas_munmap() which was introduced here.
> > > > >
> > > > > Liam,
> > > > >
> > > > > I'm getting a similar crash on arm64 -- the allocator is madvise(),
> > > > > not mprotect(). Please take a look.
> > > >
> > > > Another crash on x86_64, which seems different:
> > >
> > > Thanks for this.  I was able to reproduce the other crashes that you and
> > > Qian reported.  I've sent out a patch set to Andrew to apply to the
> > > branch which includes the fix for them and an unrelated issue discovered
> > > when I wrote the testcases to cover what was going on here.
> >
> > Thanks. I'm restarting the test and will report the results in a few hours.
> >
> > > > BUG: KASAN: slab-out-of-bounds in mab_mas_cp+0x2d9/0x6c0
> > > > Write of size 136 at addr ffff88c5a2319c80 by task stress-ng/18461
> >                                                        ^^^^^^^^^
> >
> > > As for this crash, I was unable to reproduce and the code I just sent
> > > out changes this code a lot.  Was this running with "trinity -c madvise"
> > > or another use case/fuzzer?
> >
> > This is also stress-ng (same as the one on arm64). The test stopped
> > before it could try syzkaller (fuzzer).
>
> Thanks.  What are the arguments to stress-ng you use?  I've run
> "stress-ng --class vm -a 20 -t 600s --temp-path /tmp" until it OOMs on
> my vm, but it only has 8GB of ram.

Yes, I used the same parameters with 512GB of RAM, and the kernel with
KASAN and other debug options.