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Wed, 29 Apr 2026 04:58:40 -0700 (PDT) Received: from vini ([2401:4900:8fcb:3097:5ced:f23a:32ed:4b52]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-364a011512dsm2822040a91.4.2026.04.29.04.58.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 29 Apr 2026 04:58:40 -0700 (PDT) From: Vineet Agarwal To: akpm@linux-foundation.org, david@kernel.org, ljs@kernel.org, shuah@kernel.org Cc: ziy@nvidia.com, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, Vineet Agarwal Subject: [PATCH v5] selftests/mm: khugepaged: initialize file contents via mmap Date: Wed, 29 Apr 2026 17:28:16 +0530 Message-ID: <20260429115816.98824-1-agarwal.vineet2006@gmail.com> X-Mailer: git-send-email 2.54.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit file_setup_area() currently allocates anonymous memory, fills it, and writes it into the backing file used for collapse testing. Instead of copying data through write(), resize the file with ftruncate(), map it directly with MAP_SHARED, and initialize the mapped area in place. This simplifies the setup path and avoids the need for explicit partial write handling. Signed-off-by: Vineet Agarwal v4 -> v5: - Restore msync() to keep folios clean for READ_ONLY_THP_FOR_FS - Remove O_DSYNC since msync() handles synchronization - Simplify mmap() check and drop unnecessary cleanup in error paths --- tools/testing/selftests/mm/khugepaged.c | 18 +++++++++++++++--- 1 file changed, 15 insertions(+), 3 deletions(-) diff --git a/tools/testing/selftests/mm/khugepaged.c b/tools/testing/selftests/mm/khugepaged.c index 3fe7ef04ac62..c8393ca52cab 100644 --- a/tools/testing/selftests/mm/khugepaged.c +++ b/tools/testing/selftests/mm/khugepaged.c @@ -373,7 +373,7 @@ static void *file_setup_area(int nr_hpages) unlink(finfo.path); /* Cleanup from previous failed tests */ printf("Creating %s for collapse%s...", finfo.path, finfo.type == VMA_SHMEM ? " (tmpfs)" : ""); - fd = open(finfo.path, O_DSYNC | O_CREAT | O_RDWR | O_TRUNC | O_EXCL, + fd = open(finfo.path, O_CREAT | O_RDWR | O_TRUNC | O_EXCL, 777); if (fd < 0) { perror("open()"); @@ -381,9 +381,21 @@ static void *file_setup_area(int nr_hpages) } size = nr_hpages * hpage_pmd_size; - p = alloc_mapping(nr_hpages); + if (ftruncate(fd, size)) { + perror("ftruncate()"); + exit(EXIT_FAILURE); + } + p = mmap(BASE_ADDR, size, PROT_READ | PROT_WRITE, + MAP_SHARED, fd, 0); + if (p != BASE_ADDR) { + perror("mmap()"); + exit(EXIT_FAILURE); + } fill_memory(p, 0, size); - write(fd, p, size); + if (msync(p, size, MS_SYNC)) { + perror("msync()"); + exit(EXIT_FAILURE); + } close(fd); munmap(p, size); success("OK"); -- 2.54.0