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b=MlBeAgA48j8VO5jAtfgWxcnZXQvmNu++VkSIk+GO4CuQ3EjcyfQL2cdB/WkkIhEZZ c+YqxP3WVizDttlHHqvUt8x/C+u/3BEe5DQF6KxF+rMmCkKG95Pm8noaiIXa9H0IKO 7mEjaEGdSkKi2Gi93UGMHyqUtGCAMUZLotM2kFxilG0oyj4V9/NpDx0C41YO8vpweB OITbE5pIxQRfYoq2u18S0dalW6Bu6K+Yogy0cDSN1lHIDoZJNNnYaQADav1Ap6LUjd Rw5zapoN+gk1mHokPVxPhJ44Yu92wJ0COCbkYejznwL4wlK8ZJmaS6jabZ6srHfqCb 1aMTJ9/G6C0aw== Date: Thu, 25 Jun 2026 15:02:11 +0100 From: Lorenzo Stoakes To: "David Hildenbrand (Arm)" Cc: Wei Yang , akpm@linux-foundation.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 Subject: Re: [PATCH] mm/page_vma_mapped: guard check_pmd() with CONFIG_TRANSPARENT_HUGEPAGE Message-ID: References: <20260624082359.2869-1-richard.weiyang@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Stat-Signature: 9sngtxi48dpujmfd3otuqy8uwipie99n X-Rspamd-Queue-Id: D5515A0018 X-Rspam-User: X-Rspamd-Server: rspam01 X-HE-Tag: 1782396139-306924 X-HE-Meta: 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 05uWVLqI ovvi9Kmfgd1B5p5taBNZFw7GTLn3darRvrO9qv5pRIM0G5nDStQYdTwcMpnJGFTMk29KU3vLS5U8zdWUXFZYxlgNaMeBU4Q5G0TuYu73ztApSLM3ybCOKRW/uSObSyhzwWTO/VkP4/7g3i1S/m1HKkmdHK8Y9mCDwohLwzu5AKCj4DhPWyaBVOjIryfVomdNdpLPppLbqFVHQ8LusixdPs7fF73tuJugT4WaGv93w7zdemD5VxYLb0BCv87Xprib5EoW4/nhhmlPCgG1Tqj1nC5ImIwU5Iq2hXzyoz9jh8oETlFCGC8YwHKQc6Mv0C4X+deT/TIjy9c3fsjcuj92s+jICiKS0Xvu/yEDbZUKJEI0X7UZNBoclZFQiSg== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Jun 25, 2026 at 03:49:59PM +0200, David Hildenbrand (Arm) wrote: > On 6/25/26 15:45, Lorenzo Stoakes wrote: > > On Wed, Jun 24, 2026 at 08:23:59AM +0000, Wei Yang wrote: > >> The kernel test robot reported a build failure on the parisc architecture > >> when expanding HPAGE_PMD_NR in check_pmd(). > > > > Let me first say that I absolutely hate that we continue to support museum > > piece architectures to the point that we have to make changes in core code > > to accommodate them. > > I wonder why we shouldn't be able to trigger that on other archs with > !CONFIG_TRANSPARENT_HUGEPAGE ? I think this should just use CONFIG_PGTABLE_HAS_HUGE_LEAVES, since that's the property that literally defines whether check_pmd() makes any sense. > > I think the code just relies on pmd_trans_huge() == false, and consequently > check_pmd will get compiled out completely. > > Now, the report was against Wei's new patch. > > There is *nothing* to be fixed for existing code. OK so it's a fix sent in the merge window, against a patch sent in the merge window. Great. I mean, let's all chill here. Sip some wine. Some brandy. Some absinthe. Perhaps even some turpentine* for the connoisseurs! Slow down a bit Wei! You're sending a lot of fiddly series that require a lot of review and we're extremely busy with review already. Please just relax and maybe go water your garden a bit. Have a cornetto :) > > > Fixes: 2aff7a4755be ("mm: Convert page_vma_mapped_walk to work on PFNs") > > is just wrong? Yes therefore it is indeed. Though it's really horrible that we relied on things getting compiled out like that... nasty! > > -- > Cheers, > > David Cheers, Lorenzo *Obligatory safety notice for the overly literal: do not do this, this is a joke.