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Fri, 15 May 2026 02:22:13 -0700 (PDT) Date: Fri, 15 May 2026 09:22:11 +0000 From: Wei Yang To: Vineet Agarwal Cc: akpm@linux-foundation.org, david@kernel.org, ljs@kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] selftests/mm: check file initialization writes in split_huge_page_test Message-ID: <20260515092211.qkmaxcofxwfdexld@master> Reply-To: Wei Yang References: <20260512074924.27721-1-agarwal.vineet2006@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260512074924.27721-1-agarwal.vineet2006@gmail.com> User-Agent: NeoMutt/20170113 (1.7.2) X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 40ACB80008 X-Stat-Signature: 8yhj1jt39r98rb4i66pgofm9a834a63k X-Rspam-User: X-HE-Tag: 1778836935-645753 X-HE-Meta: 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 sYprPuqm 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, May 12, 2026 at 01:19:24PM +0530, Vineet Agarwal wrote: >create_pagecache_thp_and_fd() fills the backing file for the >pagecache THP tests using repeated write() calls, but the return >value is never checked. > >If a write fails or completes only partially, the test may continue >with an incompletely initialized file and produce misleading results. > >Check the result of write() and fail the test if the expected number >of bytes was not written. > >Signed-off-by: Vineet Agarwal >--- > tools/testing/selftests/mm/split_huge_page_test.c | 13 ++++++++++--- > 1 file changed, 10 insertions(+), 3 deletions(-) > >diff --git a/tools/testing/selftests/mm/split_huge_page_test.c b/tools/testing/selftests/mm/split_huge_page_test.c >index 500d07c4938b..eab69b0f59a0 100644 >--- a/tools/testing/selftests/mm/split_huge_page_test.c >+++ b/tools/testing/selftests/mm/split_huge_page_test.c >@@ -609,9 +609,16 @@ static int create_pagecache_thp_and_fd(const char *testfile, size_t fd_size, > assert(fd_size % sizeof(buf) == 0); > for (i = 0; i < sizeof(buf); i++) > buf[i] = (unsigned char)i; >- for (i = 0; i < fd_size; i += sizeof(buf)) >- write(*fd, buf, sizeof(buf)); >- >+ for (i = 0; i < fd_size; i += sizeof(buf)) { >+ ssize_t written; >+ >+ written = write(*fd, buf, sizeof(buf)); >+ if (written != sizeof(buf)) { >+ ksft_perror("write testfile"); >+ close(*fd); >+ goto err_out_unlink; Maybe we can "goto err_out_close" and remove the close() here? Apart from this, I found on error writing to /proc/sys/vm/drop_caches in below, it just goto err_out_unlink, which left fd open. How about fix that at the same time. Generally, the change look good. >+ } >+ } > close(*fd); > sync(); > *fd = open("/proc/sys/vm/drop_caches", O_WRONLY); >-- >2.54.0 > -- Wei Yang Help you, Help me