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b=r6OYt0udCgq1im/weT5DxRld96EIWzlmImgUXLdANb5RuA9UvSmQ2haq6oO9mJbua QoPASXj052Zw81+MCFX1gLo3qeF6BOVBMG0GwgLp/YUCM0No14l4L4ML1ofvnJ4pX6 e/qqDWOoqT7Tty5HSYNlGWG13mLcrJYheIAP43FqcfdI6wCUycAiB7OMn2a6hYP+MT PI1XWlmkMUnf3d0eJg8eBbu8uZ1hD+lXUxsHdX8KQJ0kpjp+/Av+JQG7BPN0XqiZN1 1CiJbkzN7kGdnZWTTktylpGisbu7zCJ//ZdcYWhIJYH+/kvVJwsrCbl8Gmr6gMAo1v Ccg3TDczcIGgg== Date: Sun, 9 Nov 2025 09:43:17 +0200 From: Mike Rapoport To: "Vishal Moola (Oracle)" Cc: Arnd Bergmann , Huacai Chen , Huacai Chen , Andrew Morton , Kevin Brodsky , Jan Kara , linux-mm@kvack.org, Linux-Arch , linux-kernel@vger.kernel.org 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: X-Rspamd-Queue-Id: D7C9F140003 X-Rspamd-Server: rspam07 X-Stat-Signature: zh9gbob7ayurxfi9grxwts7r7h7rauzp X-Rspam-User: X-HE-Tag: 1762674205-789881 X-HE-Meta: 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 AuFQF4ma L7ke/hsr9dYm9O1P9p755qlUgNhDnnq4+J2o93AT6/Muh7p7i6f+TCoC1tdwsPAb1U4lpKLZ/6V9725zmq3aLq6VGnRM6xr84CF9BadrrMRv02QIxQUekUddmbMThFFmnWoF5xyZXI/ACQ2FqLcPQhJmvixBvJi76bF5O7itn5lCWZm+3ueEHJlQnVwk+mcZQc7hIXPxmtqufBSVVR9rozd5lNalrEJpwj43PaO+tw1yZ4ZINqiSoDlVJ5UMJBiu1FrFyn1CRMj+Ns867P6jLKCjttqk7t2/6oAq6qRJhQCxLTx4gtBxJAXo9WhgDBuVmm/iCKo6t7tULjPMyPMjrvSjvC0kDqpdY9l9YeQbGEzYtxEW6CND/wRzh6Q== 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, Nov 07, 2025 at 08:51:38AM -0800, Vishal Moola (Oracle) wrote: > +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. __pte_alloc_one() has gfp parameter to accommodate CONFIG_HIGHPTE that x86 used to have until quite recently and arm still has. > 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. > -- Sincerely yours, Mike.