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Tue, 05 Aug 2025 19:07:44 -0700 (PDT) Date: Wed, 6 Aug 2025 02:07:44 +0000 From: Wei Yang To: Zi Yan Cc: wang lian , Andrew Morton , linux-mm@kvack.org, Lorenzo Stoakes , David Hildenbrand , Wei Yang , Christian Brauner , Jann Horn , Kairui Song , Liam Howlett , Mark Brown , SeongJae Park , Shuah Khan , Vlastimil Babka , linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: Re: [PATCH] selftests/mm: fix FORCE_READ to read input value correctly. Message-ID: <20250806020744.yj2f7z6ntdqnv2ff@master> Reply-To: Wei Yang References: <20250805175140.241656-1-ziy@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250805175140.241656-1-ziy@nvidia.com> User-Agent: NeoMutt/20170113 (1.7.2) X-Rspamd-Queue-Id: 4D51EC0007 X-Rspam-User: X-Rspamd-Server: rspam09 X-Stat-Signature: 6iyesmg3xts5h7rhjxqfmerwo43rti8j X-HE-Tag: 1754446067-742411 X-HE-Meta: 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 MJCE8l0D 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 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 Tue, Aug 05, 2025 at 01:51:40PM -0400, Zi Yan wrote: >FORCE_READ() converts input value x to its pointer type then reads from >address x. This is wrong. If x is a non-pointer, it would be caught it >easily. But all FORCE_READ() callers are trying to read from a pointer and >FORCE_READ() basically reads a pointer to a pointer instead of the original >typed pointer. Almost no access violation was found, except the one from >split_huge_page_test. > >Fix it by implementing a simplified READ_ONCE() instead. > >Fixes: 3f6bfd4789a0 ("selftests/mm: reuse FORCE_READ to replace "asm volatile("" : "+r" (XXX));"") >Signed-off-by: Zi Yan >--- Reviewed-by: Wei Yang -- Wei Yang Help you, Help me