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[82.69.66.36]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-488ee038752sm117771055e9.9.2026.04.15.02.16.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 15 Apr 2026 02:16:25 -0700 (PDT) Date: Wed, 15 Apr 2026 10:16:23 +0100 From: David Laight To: Dev Jain Cc: "David Hildenbrand (Arm)" , akpm@linux-foundation.org, shuah@kernel.org, ljs@kernel.org, Liam.Howlett@oracle.com, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, ryan.roberts@arm.com, anshuman.khandual@arm.com, Sarthak Sharma Subject: Re: [PATCH v2] selftests/mm: Simplify byte pattern checking in mremap_test Message-ID: <20260415101623.33004858@pumpkin> In-Reply-To: <57b5d0f9-3e56-4f96-9e3a-2f475a78a8eb@arm.com> References: <20260415044509.579428-1-dev.jain@arm.com> <2e34b619-085f-4a9c-bb41-bc024fd40dd7@kernel.org> <57b5d0f9-3e56-4f96-9e3a-2f475a78a8eb@arm.com> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; arm-unknown-linux-gnueabihf) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Queue-Id: 227ED4000D X-Stat-Signature: hr9nhrpufmseiiit65j5uz1atxbd6oda X-Rspamd-Server: rspam06 X-HE-Tag: 1776244586-236808 X-HE-Meta: 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 HTr6tsRO 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, 15 Apr 2026 14:05:01 +0530 Dev Jain wrote: ... > > > > c) Remove any randomization from the test. There is no need for random > > patterns, just fill pages with increasing numbers. > > Agreed. I'd start from (say) 0x123456789abcdef0 rather than zero to avoid lots of zero bytes. > > d) Just always verify the whole regions. Without the rand() magic this > > will probably be just ... fairly fast? > > Yeah we are doing a simple memcmp() so it is fine. You don't need a copy of the buffer, just compare against the pattern that filled it. David > > I'll implement these changes. > > > > >