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[2003:d8:2f2d:8e00:a20e:59bc:3c13:4806]) by smtp.gmail.com with ESMTPSA id m15-20020a056000008f00b0031417b0d338sm3082057wrx.87.2023.08.04.11.00.26 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 04 Aug 2023 11:00:27 -0700 (PDT) Message-ID: Date: Fri, 4 Aug 2023 20:00:26 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.13.0 Subject: Re: [PATCH v3 7/7] selftest/mm: ksm_functional_tests: Add PROT_NONE test Content-Language: en-US To: Peter Xu 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 References: <20230803143208.383663-1-david@redhat.com> <20230803143208.383663-8-david@redhat.com> From: David Hildenbrand Organization: Red Hat In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On 03.08.23 21:06, Peter Xu wrote: > 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.. Oh, indeed, thanks! > >> + ksft_test_result_fail("ptrace write failed\n"); >> + goto unmap; >> + } >> + } > > Acked-by: Peter Xu > Thanks! -- Cheers, David / dhildenb