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[99.254.144.39]) by smtp.gmail.com with ESMTPSA id oo13-20020a05620a530d00b007339c5114a9sm111503qkn.103.2023.08.03.12.06.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 03 Aug 2023 12:06:41 -0700 (PDT) Date: Thu, 3 Aug 2023 15:06:40 -0400 From: Peter Xu To: David Hildenbrand Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, kvm@vger.kernel.org, linux-kselftest@vger.kernel.org, Andrew Morton , Linus Torvalds , liubo , Matthew Wilcox , Hugh Dickins , Jason Gunthorpe , John Hubbard , Mel Gorman , Shuah Khan , Paolo Bonzini Subject: Re: [PATCH v3 7/7] selftest/mm: ksm_functional_tests: Add PROT_NONE test Message-ID: References: <20230803143208.383663-1-david@redhat.com> <20230803143208.383663-8-david@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20230803143208.383663-8-david@redhat.com> Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org On Thu, Aug 03, 2023 at 04:32:08PM +0200, David Hildenbrand wrote: > Let's test whether merging and unmerging in PROT_NONE areas works as > expected. > > Pass a page protection to mmap_and_merge_range(), which will trigger > an mprotect() after writing to the pages, but before enabling merging. > > Make sure that unsharing works as expected, by performing a ptrace write > (using /proc/self/mem) and by setting MADV_UNMERGEABLE. > > Note that this implicitly tests that ptrace writes in an inaccessible > (PROT_NONE) mapping work as expected. > > Signed-off-by: David Hildenbrand [...] > +static void test_prot_none(void) > +{ > + const unsigned int size = 2 * MiB; > + char *map; > + int i; > + > + ksft_print_msg("[RUN] %s\n", __func__); > + > + map = mmap_and_merge_range(0x11, size, PROT_NONE, false); > + if (map == MAP_FAILED) > + goto unmap; > + > + /* Store a unique value in each page on one half using ptrace */ > + for (i = 0; i < size / 2; i += pagesize) { > + lseek(mem_fd, (uintptr_t) map + i, SEEK_SET); > + if (write(mem_fd, &i, sizeof(size)) != sizeof(size)) { sizeof(i)? May not matter a huge lot, though.. > + ksft_test_result_fail("ptrace write failed\n"); > + goto unmap; > + } > + } Acked-by: Peter Xu -- Peter Xu