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[34.123.190.156]) by smtp.gmail.com with ESMTPSA id s21-20020a02cf35000000b0041cd626ea0csm2704691jar.147.2023.08.28.13.10.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 28 Aug 2023 13:10:15 -0700 (PDT) Date: Mon, 28 Aug 2023 20:10:15 +0000 From: Joel Fernandes To: Lorenzo Stoakes Cc: linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, Shuah Khan , Vlastimil Babka , Michal Hocko , Linus Torvalds , Kirill A Shutemov , "Liam R. Howlett" , "Paul E. McKenney" , Suren Baghdasaryan , Kalesh Singh , Lokesh Gidra Subject: Re: [PATCH v5 6/7] selftests: mm: Add a test for remapping within a range Message-ID: <20230828201015.GE1621761@google.com> References: <20230822015501.791637-1-joel@joelfernandes.org> <20230822015501.791637-7-joel@joelfernandes.org> <08ce8c61-e7a2-417a-a3cc-d20861753ae8@lucifer.local> <20230828185912.GD1621761@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Aug 28, 2023 at 08:38:17PM +0100, Lorenzo Stoakes wrote: > On Mon, Aug 28, 2023 at 06:59:12PM +0000, Joel Fernandes wrote: > > On Sun, Aug 27, 2023 at 11:15:20AM +0100, Lorenzo Stoakes wrote: > > > On Sun, Aug 27, 2023 at 10:57:59AM +0100, Lorenzo Stoakes wrote: > > > [snip] > > > > > > > > +/* > > > > > + * Verify that an mremap within a range does not cause corruption > > > > > + * of unrelated part of range. > > > > > + * > > > > > + * Consider the following range which is 2MB aligned and is > > > > > + * a part of a larger 10MB range which is not shown. Each > > > > > + * character is 256KB below making the source and destination > > > > > > Just noticed, I think you misspeak here, as this test doens't seem to > > > offset by 256 KiB? That is the strategy for mremap_move_1mb_from_start() > > > rather than this test so perhaps comment needs to be moved around? > > > > > > * 2MB each. The lower case letters are moved (s to d) and the > > > * upper case letters are not moved. The below test verifies > > > * that the upper case S letters are not corrupted by the > > > * adjacent mremap. > > > * > > > * |DDDDddddSSSSssss| > > > */ > > > static void mremap_move_within_range(char pattern_seed) > > > > Here we are moving 1MB within a 4MB zone of a large mapping. Each character > > 's' or 'd' is 256KB. The 256KB there is just for illustration and not really > > significant as such. The 'ssss' is moved to 'dddd' 1MB each. Here we make > > Ahhh I see. I find that a little confusing here, perhaps clearer to say 'each > block of letters is 1 MiB in size' or something? Sure, I'll do that. > Cheers! Cheers. And thanks for the reviews! - Joel