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Sat, 30 Aug 2025 00:46:28 -0700 (PDT) Date: Sat, 30 Aug 2025 07:46:27 +0000 From: Wei Yang To: Andrew Morton Cc: Wei Yang , david@redhat.com, lorenzo.stoakes@oracle.com, ziy@nvidia.com, baolin.wang@linux.alibaba.com, linux-mm@kvack.org, linux-kselftest@vger.kernel.org Subject: Re: [PATCH] selftests/mm: directly add pagesize instead of increase until page size Message-ID: <20250830074627.pitdp64svss6slyk@master> Reply-To: Wei Yang References: <20250830023102.14981-1-richard.weiyang@gmail.com> <20250829200953.1757e85542b1126c4881d600@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250829200953.1757e85542b1126c4881d600@linux-foundation.org> User-Agent: NeoMutt/20170113 (1.7.2) X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: AE345140002 X-Stat-Signature: ekrchfyah1tnfdbbx4s4pfkfcob81s6s X-Rspam-User: X-HE-Tag: 1756539990-793745 X-HE-Meta: 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 OBoXLs4g 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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 Fri, Aug 29, 2025 at 08:09:53PM -0700, Andrew Morton wrote: >On Sat, 30 Aug 2025 02:31:02 +0000 Wei Yang wrote: > >> The check of is_backed_by_folio() is done on each page. >> >> Directly move pointer to next page instead of increase one and check if >> it is page size aligned. > >Why? > >> --- a/tools/testing/selftests/mm/split_huge_page_test.c >> +++ b/tools/testing/selftests/mm/split_huge_page_test.c >> @@ -423,9 +423,8 @@ static void split_pte_mapped_thp(void) >> >> /* smap does not show THPs after mremap, use kpageflags instead */ >> thp_size = 0; >> - for (i = 0; i < pagesize * 4; i++) >> - if (i % pagesize == 0 && >> - is_backed_by_folio(&pte_mapped[i], pmd_order, pagemap_fd, kpageflags_fd)) >> + for (i = 0; i < pagesize * 4; i += pagesize) >> + if (is_backed_by_folio(&pte_mapped[i], pmd_order, pagemap_fd, kpageflags_fd)) >> thp_size++; > >Looks like we're doing more work. Is there something wrong with the >existing code? Excuse me if I misunderstand the code. Originally, i iterate from 0 to pagesize * 4 one by one and call is_backed_by_folio() when i is 0, 4096, 8192, 12288. The change makes i just iterate on 0, 4096, 8192, 12288 and call is_backed_by_folio() respectively. Current code is not wrong, but not necessary to iterate one by one. -- Wei Yang Help you, Help me