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From:   Andrey Konovalov <andreyknvl@gmail.com>
Date:   Mon, 23 Oct 2023 18:17:40 +0200
Message-ID: <CA+fCnZfRh=a1VQx7CaHAjTQw9888jxFHB0dJv5hkBW6v3njdkQ@mail.gmail.com>
Subject: Re: [PATCH v2 12/19] lib/stackdepot: use list_head for stack record links
To:     Alexander Potapenko <glider@google.com>,
        Anders Roxell <anders.roxell@linaro.org>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        andrey.konovalov@linux.dev, Marco Elver <elver@google.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        Vlastimil Babka <vbabka@suse.cz>, kasan-dev@googlegroups.com,
        Evgenii Stepanov <eugenis@google.com>,
        Oscar Salvador <osalvador@suse.de>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org,
        Andrey Konovalov <andreyknvl@google.com>, arnd@arndb.de,
        sfr@canb.auug.org.au
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On Mon, Oct 9, 2023 at 2:16=E2=80=AFPM Alexander Potapenko <glider@google.c=
om> wrote:
>
> On Sat, Sep 16, 2023 at 10:04=E2=80=AFPM Andrew Morton
> <akpm@linux-foundation.org> wrote:
> >
> > On Sat, 16 Sep 2023 19:43:35 +0200 Anders Roxell <anders.roxell@linaro.=
org> wrote:
> >
> > > On 2023-09-13 19:14, andrey.konovalov@linux.dev wrote:
> > > > From: Andrey Konovalov <andreyknvl@google.com>
> > > >
> > > > Switch stack_record to use list_head for links in the hash table
> > > > and in the freelist.
> > > >
> > > > This will allow removing entries from the hash table buckets.
> > > >
> > > > This is preparatory patch for implementing the eviction of stack re=
cords
> > > > from the stack depot.
> > > >
> > > > Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
> > > >
> > >
> > > Building on an arm64 kernel from linux-next tag next-20230915, and bo=
ot
> > > that in QEMU. I see the following kernel panic.
> > >
> > > ...
> > >
> > > The full log can be found [1] and the .config file [2]. I bisected do=
wn
> > > to this commit, see the bisect log [3].
>
> I am also seeing similar crashes on an x86 KMSAN build.
>
> They are happening when in the following code:
>
>         list_for_each(pos, bucket) {
>                 found =3D list_entry(pos, struct stack_record, list);
>                 if (found->hash =3D=3D hash &&
>                     found->size =3D=3D size &&
>                     !stackdepot_memcmp(entries, found->entries, size))
>                         return found;
>         }
>
> `found` is NULL
>
> @Andrey, could you please take a look?

Found a bug, will fix in v3. Thank you!