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[67.164.59.41]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-34362f1f231sm936024a91.10.2025.11.07.08.51.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 07 Nov 2025 08:51:40 -0800 (PST) Date: Fri, 7 Nov 2025 08:51:38 -0800 From: "Vishal Moola (Oracle)" To: Arnd Bergmann Cc: Huacai Chen , Huacai Chen , Andrew Morton , Kevin Brodsky , Jan Kara , linux-mm@kvack.org, Linux-Arch , linux-kernel@vger.kernel.org, Mike Rapoport Subject: Re: [PATCH Resend] mm: Refine __{pgd,p4d,pud,pmd,pte}_alloc_one_*() about HIGHMEM Message-ID: References: <20251107095922.3106390-1-chenhuacai@loongson.cn> <0fbcde0d-4fed-4aa6-b0bf-c4400b9b1cf5@app.fastmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <0fbcde0d-4fed-4aa6-b0bf-c4400b9b1cf5@app.fastmail.com> X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 356A1C000B X-Stat-Signature: nsz6s84irtnnbzxmdojmm5ordddrrimi X-HE-Tag: 1762534301-765129 X-HE-Meta: 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 W8XCYyct 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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: +Cc: Mike On Fri, Nov 07, 2025 at 12:21:38PM +0100, Arnd Bergmann wrote: > On Fri, Nov 7, 2025, at 10:59, Huacai Chen wrote: > > __{pgd,p4d,pud,pmd,pte}_alloc_one_*() always allocate pages with GFP > > flag GFP_PGTABLE_KERNEL/GFP_PGTABLE_USER. These two macros are defined > > as follows: > > > > #define GFP_PGTABLE_KERNEL (GFP_KERNEL | __GFP_ZERO) > > #define GFP_PGTABLE_USER (GFP_PGTABLE_KERNEL | __GFP_ACCOUNT) > > > > There is no __GFP_HIGHMEM in them, so we needn't to clear __GFP_HIGHMEM > > explicitly. > > > > Signed-off-by: Huacai Chen > > --- > > Resend because the lines begin with # was eaten by git. > > Thanks for your patch, this is an area I've also started > looking at, with the intention to reduce the references > to __GFO_HIGHMEM to the minimum we need for supporting the > remaining platforms that need to use highmem somewhere. Yay! Thanks for doing that, I like less highmem :) > I'm not sure what the reason is for your patch, I assume > this is meant purely as a cleanup, correct? Are you looking > at a wider set of related cleanups, or did you just notice > this one instance? > > Note that for the moment, the 32-bit arm __pte_alloc_one() function > still passes __GFP_HIGHMEM when CONFIG_HIGHPTE is set, though > I would like to remove that code path. Unless we remove > that at the same time, this should probably be explained in your > patch description. Skimming the functions, __pte_alloc_one_kernel() doesn't get passed in a gfp, while __pte_alloc_one() does. IOW I __pte_alloc_one_kernel() cares about architecture gfp, while the latter does care - so they are 2 very different cases. Might be helpful to explain, although I don't think it matters much. I've cc-ed Mike, he might have more useful opinions these functions.