linux-kernel - Re: [PATCH 12/32] kmsan: Allow disabling KMSAN checks for the current task

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Message-ID: <CAG_fn=XVJNZLtHj2n3DP5ETBzgoUZL0jQFX7uw4z9Pj2vGbUPw@mail.gmail.com>
Date:   Thu, 16 Nov 2023 09:56:04 +0100
From:   Alexander Potapenko <glider@...gle.com>
To:     Ilya Leoshkevich <iii@...ux.ibm.com>
Cc:     Alexander Gordeev <agordeev@...ux.ibm.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Christoph Lameter <cl@...ux.com>,
        David Rientjes <rientjes@...gle.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Marco Elver <elver@...gle.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Pekka Enberg <penberg@...nel.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Christian Borntraeger <borntraeger@...ux.ibm.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Hyeonggon Yoo <42.hyeyoo@...il.com>,
        kasan-dev@...glegroups.com, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, linux-s390@...r.kernel.org,
        linux-trace-kernel@...r.kernel.org,
        Mark Rutland <mark.rutland@....com>,
        Roman Gushchin <roman.gushchin@...ux.dev>,
        Sven Schnelle <svens@...ux.ibm.com>
Subject: Re: [PATCH 12/32] kmsan: Allow disabling KMSAN checks for the current task

On Wed, Nov 15, 2023 at 9:34 PM Ilya Leoshkevich <iii@...ux.ibm.com> wrote:
>
> Like for KASAN, it's useful to temporarily disable KMSAN checks around,
> e.g., redzone accesses.

This example is incorrect, because KMSAN does not have redzones.
You are calling these functions from "mm: slub: Let KMSAN access
metadata", which mentiones redzones in kfree(), but the description is
still somewhat unclear.
Can you provide more insight about what is going on? Maybe we can fix
those accesses instead of disabling KMSAN?