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In-Reply-To: <20230315125256.22772-1-fmdefrancesco@gmail.com>
References: <20230315125256.22772-1-fmdefrancesco@gmail.com>
From:   Stephen Boyd <swboyd@chromium.org>
User-Agent: alot/0.10
Date:   Fri, 17 Mar 2023 12:04:06 -0700
Message-ID: <CAE-0n50=j=GPQA=wQa5wE=P2T0ipOoOn6ekhPVAJhr5nMkiVnw@mail.gmail.com>
Subject: Re: [PATCH] module/decompress: Never use kunmap() for local un-mappings
To:     Chris Down <chris@chrisdown.name>,
        Daniel Thompson <daniel.thompson@linaro.org>,
        Douglas Anderson <dianders@chromium.org>,
        "Fabio M. De Francesco" <fmdefrancesco@gmail.com>,
        Jason Wessel <jason.wessel@windriver.com>,
        Jiri Kosina <jikos@kernel.org>,
        Joe Lawrence <joe.lawrence@redhat.com>,
        Josh Poimboeuf <jpoimboe@kernel.org>,
        Luis Chamberlain <mcgrof@kernel.org>,
        Miroslav Benes <mbenes@suse.cz>,
        Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Nick Terrell <terrelln@fb.com>, Petr Mladek <pmladek@suse.com>,
        Tom Rix <trix@redhat.com>, bpf@vger.kernel.org,
        kgdb-bugreport@lists.sourceforge.net, linux-kernel@vger.kernel.org,
        linux-modules@vger.kernel.org, live-patching@vger.kernel.org,
        llvm@lists.linux.dev
Cc:     Piotr Gorski <piotrgorski@cachyos.org>,
        Dmitry Torokhov <dmitry.torokhov@gmail.com>,
        Ira Weiny <ira.weiny@intel.com>
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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@cachyos.org>
> Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
> Cc: Luis Chamberlain <mcgrof@kernel.org>
> Cc: Stephen Boyd <swboyd@chromium.org>
> Cc: Ira Weiny <ira.weiny@intel.com>
> Fixes: 169a58ad824d ("module/decompress: Support zstd in-kernel decompression")
> Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
> ---

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