linux-kernel - Re: [PATCH 00/15] stackdepot: allow evicting stack traces

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Message-ID: <CA+fCnZf7eHV3Mb27x6HnNyS9RoS2AYQTtYxxLrv5QXKhMKEqcg@mail.gmail.com>
Date:   Wed, 13 Sep 2023 19:10:57 +0200
From:   Andrey Konovalov <andreyknvl@...il.com>
To:     Kuan-Ying Lee (李冠穎) 
        <Kuan-Ying.Lee@...iatek.com>
Cc:     "vbabka@...e.cz" <vbabka@...e.cz>,
        "andreyknvl@...gle.com" <andreyknvl@...gle.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "kasan-dev@...glegroups.com" <kasan-dev@...glegroups.com>,
        "dvyukov@...gle.com" <dvyukov@...gle.com>,
        "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
        "elver@...gle.com" <elver@...gle.com>,
        "eugenis@...gle.com" <eugenis@...gle.com>,
        "andrey.konovalov@...ux.dev" <andrey.konovalov@...ux.dev>,
        "glider@...gle.com" <glider@...gle.com>
Subject: Re: [PATCH 00/15] stackdepot: allow evicting stack traces

On Tue, Sep 5, 2023 at 4:48 AM 'Kuan-Ying Lee (李冠穎)' via kasan-dev
<kasan-dev@...glegroups.com> wrote:
>
> > > 3. With the number of stackdepot users increasing, each having
> > > their
> > > distinct set of stacks from others, would it make sense to create
> > > separate
> > > "storage instance" for each user instead of putting everything in a
> > > single
> > > shared one?
> >
> > This shouldn't be hard to implement. However, do you see any
> > particular use cases for this?
> >
> > One thing that comes to mind is that the users will then be able to
> > create/destroy stack depot instances when required. But I don't know
> > if any of the users need this: so far they all seem to require stack
> > depot throughout the whole lifetime of the system.
> >
> Maybe we can use evition in page_owner and slub_debug
> (SLAB_STORE_USER).
>
> After we update page_owner->handle, we could evict the previous
> handle?

We can definitely adapt more users to the new API. My comment was
related to the suggestion of splitting stack depot storages for
different users.

But actually I have a response to my question about the split: if each
user has a separate stack depot storage instance, they can set the
maximum stack trace size as they desire, and thus save up on memory.