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b=CgSdgBUBFiDt3okUqvtkGMIEYDUqXbwvZ/kjzwcVxkwFMwp8MUfX5FM+8aDwEAmE+ Mg8xwbKCQs/+Mt2df3CjIm90aQzLHuP+nRcvCA1T4uCofIcr6/zQCX7rXRk60R8TUM qh8AelK31eg/QzpxOhA7yTIwKhOTdv5SBLf/86YI= Date: Thu, 21 Mar 2024 14:51:46 -0700 From: Andrew Morton To: Dev Jain Cc: shuah@kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, Anshuman.Khandual@arm.com Subject: Re: [PATCH] selftests/mm: Confirm VA exhaustion without reliance on correctness of mmap() Message-Id: <20240321145146.a3ce8a1e247371e33a437978@linux-foundation.org> In-Reply-To: <20240321103522.516097-1-dev.jain@arm.com> References: <20240321103522.516097-1-dev.jain@arm.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Stat-Signature: 7df99y5pp51mrnoc95qmw1f8puhjabt7 X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: C75C7A0020 X-Rspam-User: X-HE-Tag: 1711057911-766074 X-HE-Meta: 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 1KMKnkB2 6K1htFnczn30fYK/ULZv/iVSqyBbhUwQNl7/EFDDxL0es5elCe4Bysq0IizxB1R6qjmZ7eVd3x4qxm5weOter+35W3O76DuwMK9rYcuI6rv926aQ9mmWwwrsaBOLxIiCncgwb7adLH9C8dtGsD2ACKWxf+Rx4p68V9G3Rajckt+3qRFA6hgEFPw4yDGlKJ/heEZ+OQ0wpkOCMYnFrn2PdhNuMWvVhFUtJKmmOTz1nkVuQZHqr4Tqge2lPbQ== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, 21 Mar 2024 16:05:22 +0530 Dev Jain wrote: > Currently, VA exhaustion is being checked by passing a hint to mmap() and > expecting it to fail. This patch makes a stricter test by successful write() > calls from /proc/self/maps to a dump file, confirming that a free chunk is > indeed not available. What's wrong with the current approach?