linux-kernel - Re: [PATCH] powerpc/32: Add warning on misaligned copy_page() or clear

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Message-Id: <46DlGt49BMz9sPW@ozlabs.org>
Date:   Thu, 22 Aug 2019 23:09:10 +1000 (AEST)
From:   Michael Ellerman <patch-notifications@...erman.id.au>
To:     Christophe Leroy <christophe.leroy@....fr>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>
Cc:     linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] powerpc/32: Add warning on misaligned copy_page() or clear_page()

On Fri, 2019-08-16 at 07:52:20 UTC, Christophe Leroy wrote:
> copy_page() and clear_page() expect page aligned destination, and
> use dcbz instruction to clear entire cache lines based on the
> assumption that the destination is cache aligned.
> 
> As shown during analysis of a bug in BTRFS filesystem, a misaligned
> copy_page() can create bugs that are difficult to locate (see Link).
> 
> Add an explicit WARNING when copy_page() or clear_page() are called
> with misaligned destination.
> 
> Signed-off-by: Christophe Leroy <christophe.leroy@....fr>
> Cc: Erhard F. <erhard_f@...lbox.org>
> Link: https://bugzilla.kernel.org/show_bug.cgi?id=204371

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/7ab0b7cb8951d4095d73e203759b74d41916e455

cheers