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Thu, 03 Sep 2026 19:02:30 -0700 (PDT) Date: Fri, 4 Sep 2026 02:02:29 +0000 From: Wei Yang To: Andrew Morton Cc: Wei Yang , david@kernel.org, ljs@kernel.org, riel@surriel.com, liam@infradead.org, vbabka@kernel.org, harry@kernel.org, jannh@google.com, willy@infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, lance.yang@linux.dev, Kiryl Shutsemau , Hugh Dickins Subject: Re: [PATCH] mm/page_vma_mapped: guard check_pmd() with CONFIG_TRANSPARENT_HUGEPAGE Message-ID: <20260904020229.etsxwqw74ug7c7hs@master> Reply-To: Wei Yang References: <20260624082359.2869-1-richard.weiyang@gmail.com> <20260902200220.408ae7e8a28d3af4e82fd060@linux-foundation.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260902200220.408ae7e8a28d3af4e82fd060@linux-foundation.org> User-Agent: NeoMutt/20170113 (1.7.2) On Wed, Sep 02, 2026 at 08:02:20PM -0700, Andrew Morton wrote: >On Wed, 24 Jun 2026 08:23:59 +0000 Wei Yang wrote: > >> The kernel test robot reported a build failure on the parisc architecture >> when expanding HPAGE_PMD_NR in check_pmd(). >> >> mm/page_vma_mapped.c:142:13: note: in expansion of macro 'HPAGE_PMD_NR' >> if ((pfn + HPAGE_PMD_NR - 1) < pvmw->pfn) >> ^~~~~~~~~~~~ >> >> The config [1] in report link shows neither TRANSPARENT_HUGEPAGE nor >> HUGETLB_PAGE is defined. Then trigger the BUILD_BUG. >> >> Fix it by define check_pmd() under CONFIG_TRANSPARENT_HUGEPAGE. >> >> [1]: https://download.01.org/0day-ci/archive/20260624/202606240042.ffPsEXVc-lkp@intel.com/config >> >> Fixes: 2aff7a4755be ("mm: Convert page_vma_mapped_walk to work on PFNs") >> Signed-off-by: Wei Yang >> Reported-by: kernel test robot >> Closes: https://lore.kernel.org/oe-kbuild-all/202606240042.ffPsEXVc-lkp@intel.com/ >> >> ... >> >> --- a/mm/page_vma_mapped.c >> +++ b/mm/page_vma_mapped.c >> @@ -136,6 +136,7 @@ static bool check_pte(struct page_vma_mapped_walk *pvmw, unsigned long pte_nr) >> return true; >> } >> >> +#ifdef CONFIG_TRANSPARENT_HUGEPAGE >> /* Returns true if the two ranges overlap. Careful to not overflow. */ >> static bool check_pmd(unsigned long pfn, struct page_vma_mapped_walk *pvmw) >> { >> @@ -145,6 +146,12 @@ static bool check_pmd(unsigned long pfn, struct page_vma_mapped_walk *pvmw) >> return false; >> return true; >> } >> +#else >> +static bool check_pmd(unsigned long pfn, struct page_vma_mapped_walk *pvmw) >> +{ >> + return false; >> +} >> +#endif >> >> static void step_forward(struct page_vma_mapped_walk *pvmw, unsigned long size) >> { > >lgtm, thanks. > >You provoked Sashiko into talking about memory corruption and kernel >panics in page_vma_mapped.c. Usual stuff. > > https://sashiko.dev/#/patchset/20260624082359.2869-1-richard.weiyang@gmail.com > Hi, Andrew IIUC, the issue reported by Sashiko is fixed by commit f84ca9b1888d ("mm/page_vma_mapped: fix device-private PMD handling") >I'll cc likely suspects but boy do we need a way of being more >organized about this. The build error fixed here is introduced by v3 [1], in which check_pmd() is invoked outside a conditional "if". Then v4 [2] and v5 [3] call check_pmd() in a conditional "if" and at last David fix this with IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE). Do you suggest still conditionally define check_pmd()? I may not follow your point. Have a good day. [1]: https://lore.kernel.org/all/20260622130651.23359-1-richard.weiyang@gmail.com/ [2]: https://lore.kernel.org/all/20260624065353.1622-1-richard.weiyang@gmail.com/T/#u [3]: https://lore.kernel.org/linux-mm/20260630021540.17297-1-richard.weiyang@gmail.com/ -- Wei Yang Help you, Help me