linux-kernel - Re: [GIT PULL] MM updates for 6.1-rc1

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Date:   Tue, 11 Oct 2022 10:24:27 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Alexander Potapenko <glider@...gle.com>,
        Andrey Konovalov <andreyknvl@...gle.com>,
        Josh Poimboeuf <jpoimboe@...nel.org>,
        mm-commits@...r.kernel.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [GIT PULL] MM updates for 6.1-rc1

On Mon, Oct 10, 2022 at 06:20:00PM -0700, Linus Torvalds wrote:
> The other thing I notice from just doing a build is that I now get
> 
>    vmlinux.o: warning: objtool: kasan_report+0x12: call to
> stackleak_track_stack() with UACCESS enabled

So kasan_report() is already marked as being special; and it does the
mandatory user_access_save() / user_access_restore() things to fix it
up.

But it looks like kasan code itself is now getting instrumented by the
stackleak stuff and that inserts a call outside of the
user_access_save()/restore() thing, and *that* is getting flagged.

Looking at mm/kasan/Makefile it disables a lot of the instrumentation,
but perhaps not enough?

I've not yet tried to reproduce, I'm taking this is allyesconfig or
something glorious like that? LLVM-15 ?