linux-kernel - Re: [PATCH] module/decompress: Never use kunmap() for local un-mappings

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Message-ID: <CAE-0n50=j=GPQA=wQa5wE=P2T0ipOoOn6ekhPVAJhr5nMkiVnw@mail.gmail.com>
Date:   Fri, 17 Mar 2023 12:04:06 -0700
From:   Stephen Boyd <swboyd@...omium.org>
To:     Chris Down <chris@...isdown.name>,
        Daniel Thompson <daniel.thompson@...aro.org>,
        Douglas Anderson <dianders@...omium.org>,
        "Fabio M. De Francesco" <fmdefrancesco@...il.com>,
        Jason Wessel <jason.wessel@...driver.com>,
        Jiri Kosina <jikos@...nel.org>,
        Joe Lawrence <joe.lawrence@...hat.com>,
        Josh Poimboeuf <jpoimboe@...nel.org>,
        Luis Chamberlain <mcgrof@...nel.org>,
        Miroslav Benes <mbenes@...e.cz>,
        Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Nick Terrell <terrelln@...com>, Petr Mladek <pmladek@...e.com>,
        Tom Rix <trix@...hat.com>, bpf@...r.kernel.org,
        kgdb-bugreport@...ts.sourceforge.net, linux-kernel@...r.kernel.org,
        linux-modules@...r.kernel.org, live-patching@...r.kernel.org,
        llvm@...ts.linux.dev
Cc:     Piotr Gorski <piotrgorski@...hyos.org>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Ira Weiny <ira.weiny@...el.com>
Subject: Re: [PATCH] module/decompress: Never use kunmap() for local un-mappings

Quoting Fabio M. De Francesco (2023-03-15 05:52:56)
> Use kunmap_local() to unmap pages locally mapped with kmap_local_page().
>
> kunmap_local() must be called on the kernel virtual address returned by
> kmap_local_page(), differently from how we use kunmap() which instead
> expects the mapped page as its argument.
>
> In module_zstd_decompress() we currently map with kmap_local_page() and
> unmap with kunmap(). This breaks the code and so it should be fixed.
>
> Cc: Piotr Gorski <piotrgorski@...hyos.org>
> Cc: Dmitry Torokhov <dmitry.torokhov@...il.com>
> Cc: Luis Chamberlain <mcgrof@...nel.org>
> Cc: Stephen Boyd <swboyd@...omium.org>
> Cc: Ira Weiny <ira.weiny@...el.com>
> Fixes: 169a58ad824d ("module/decompress: Support zstd in-kernel decompression")
> Signed-off-by: Fabio M. De Francesco <fmdefrancesco@...il.com>
> ---

Reviewed-by: Stephen Boyd <swboyd@...omium.org>