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From: Kent Overstreet To: Mike Rapoport Cc: Matthew Wilcox , Kees Cook , Johannes Thumshirn , "linux-kernel@vger.kernel.org" , "linux-fsdevel@vger.kernel.org" , "linux-bcachefs@vger.kernel.org" , Kent Overstreet , Andrew Morton , Uladzislau Rezki , "hch@infradead.org" , "linux-mm@kvack.org" , "linux-hardening@vger.kernel.org" , song@kernel.org Subject: Re: [PATCH 07/32] mm: Bring back vmalloc_exec Message-ID: References: <3508afc0-6f03-a971-e716-999a7373951f@wdc.com> <202305111525.67001E5C4@keescook> <202305161401.F1E3ACFAC@keescook> <20230517154412.GC4967@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230517154412.GC4967@kernel.org> X-Migadu-Flow: FLOW_OUT X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,SPF_HELO_NONE,SPF_PASS, T_SCC_BODY_TEXT_LINE,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, May 17, 2023 at 06:44:12PM +0300, Mike Rapoport wrote: > On Wed, May 17, 2023 at 10:18:11AM -0400, Kent Overstreet wrote: > > On Wed, May 17, 2023 at 05:04:27PM +0300, Mike Rapoport wrote: > > > > And I'm really curious why text_poke() is needed at all. Seems like we > > could just use kmap_local() to create a temporary writeable mapping, > > On 64 bit kmap_local_page() is aliased to page_address() and does not map > anything. text_poke() is needed to actually create a temporary writable > mapping without touching page tables in vmalloc and/or direct map. Duh - thanks!