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Tue, 02 Sep 2025 01:28:55 -0700 (PDT) Date: Tue, 2 Sep 2025 08:28:55 +0000 From: Wei Yang To: David Hildenbrand Cc: Wei Yang , Zi Yan , akpm@linux-foundation.org, lorenzo.stoakes@oracle.com, baolin.wang@linux.alibaba.com, linux-mm@kvack.org, linux-kselftest@vger.kernel.org Subject: Re: [Patch v2] selftests/mm: check content to see whether mremap corrupt data Message-ID: <20250902082855.muyi3wlxbmkcwiu5@master> Reply-To: Wei Yang References: <20250831022701.2595-1-richard.weiyang@gmail.com> <61E58B7C-23D0-49FE-8D0C-CE0B672114E2@nvidia.com> <0a0b0018-9427-4201-bf53-6aeb251bc482@redhat.com> <1D88E773-C11E-4F28-A13A-1A681898198B@nvidia.com> <5a796574-0a3c-4040-b0bc-3ff757402759@redhat.com> <20250902025112.d2n3o4imeptppctd@master> <20250902081342.rthx5sopowmg4hyb@master> <05f628ba-c24b-4180-87be-e5a577dc4e4d@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <05f628ba-c24b-4180-87be-e5a577dc4e4d@redhat.com> User-Agent: NeoMutt/20170113 (1.7.2) X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: D79BE100007 X-Stat-Signature: 5aq3ne5srzrmjd5jg6sng314erhuq7is X-Rspam-User: X-HE-Tag: 1756801737-281874 X-HE-Meta: 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 9+M2HKqX 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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 Tue, Sep 02, 2025 at 10:23:51AM +0200, David Hildenbrand wrote: >On 02.09.25 10:13, Wei Yang wrote: >> On Tue, Sep 02, 2025 at 09:49:48AM +0200, David Hildenbrand wrote: >> > > > + /* >> > > > + * To challenge spitting code, we will mremap page[x] of the >> > > > + * thp[x] into a smaller area, and trigger the split from that >> > > > + * smaller area. This will end up replacing the PMD mappings in >> > > > + * the thp_area by PTE mappings first, leaving the THPs unsplit. >> > > > + */ >> >> This confuse me a little. How about move "and trigger the split from that >> smaller area" to the end? So that I know mremap convert to pte-mapping and >> leave thp unsplit. Then we do the split. >> > >After spleeping over it, what about the following? > >+ /* >+ * To challenge spitting code, we will mremap a single page of each >+ * THP (page[i] of thp[i]) in the thp_area into page_area. This will >+ * replace the PMD mappings in the thp_area by PTE mappings first, >+ * but leaving the THP unsplit, to then create a page-sized hole in >+ * the thp_area. >+ * We will then manually trigger splitting of all THPs through the >+ * single mremap'ed pages of each THP in the page_area. >+ */ > Much better, thanks :-) -- Wei Yang Help you, Help me