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([2409:8a28:f44:3764:680a:144b:d927:5a3b]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-2f2db9939b5sm5267286a91.1.2024.12.20.03.46.06 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 20 Dec 2024 03:46:14 -0800 (PST) Message-ID: <0daabd32-cba4-4345-baa8-e8c66bc899ff@bytedance.com> Date: Fri, 20 Dec 2024 19:46:04 +0800 Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 01/10] mm: Move common parts of pagetable_*_[cd]tor to helpers Content-Language: en-US To: Kevin Brodsky Cc: Peter Zijlstra , linux-mm@kvack.org, Andrew Morton , Catalin Marinas , Dave Hansen , Linus Walleij , Andy Lutomirski , "Mike Rapoport (IBM)" , Ryan Roberts , Thomas Gleixner , Will Deacon , Matthew Wilcox , linux-alpha@vger.kernel.org, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-csky@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-kernel@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, linux-openrisc@vger.kernel.org, linux-parisc@vger.kernel.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-snps-arc@lists.infradead.org, linux-um@lists.infradead.org, loongarch@lists.linux.dev, x86@kernel.org, Alexander Gordeev References: <20241219164425.2277022-1-kevin.brodsky@arm.com> <20241219164425.2277022-2-kevin.brodsky@arm.com> <20241219171920.GB26279@noisy.programming.kicks-ass.net> <75cb4ff8-eb0c-4519-a30a-f8be717ba278@arm.com> From: Qi Zheng In-Reply-To: <75cb4ff8-eb0c-4519-a30a-f8be717ba278@arm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Hi Kevin, On 2024/12/20 18:49, Kevin Brodsky wrote: > Hi Peter, Qi, > > On 19/12/2024 18:19, Peter Zijlstra wrote: >> On Thu, Dec 19, 2024 at 04:44:16PM +0000, Kevin Brodsky wrote: >>> Besides the ptlock management at PTE/PMD level, all the >>> pagetable_*_[cd]tor have the same implementation. Introduce common >>> helpers for all levels to reduce the duplication. >> Uff, I forgot to Cc you on the discussion here, sorry!: >> >> https://lkml.kernel.org/r/cover.1734526570.git.zhengqi.arch@bytedance.com >> >> we now have two series doing more or less overlapping things :/ >> >> You can in fact trivially merge the all the implementations -- the >> apparent non-common bit (ptlock_free) is a no-op for all those other >> levels because they'll be having ptdesc->lock == NULL. > > Ah that is good to know, thanks for letting me know about that and Qi's > series! Fortunately there isn't that much overlap between our series - I > think we can easily sort this out. > > Qi, shall we collaborate to make our series complementary? I believe my > series covers patch 2 and 4 of your series, but it goes further by > covering all levels and all architectures, and patches introducing > ctor/dtor are already split as Alexander suggested on your series. So my > suggestion would be: > > * Remove patch 1 in my series - I'd just introduce > pagetable_{p4d,pgd}_[cd]tor with the same implementation as > pagetable_pud_[cd]tor. > * Remove patch 2 and 4 from your series and rebase it on mine. I quickly went through your patch series. It looks like my patch 2 and your patch 6 are duplicated, so you want me to remove my patch 2. But I think you may not be able to simple let arm64, riscv and x86 to use generic p4d_{alloc_one,free}(). Because even if CONFIG_PGTABLE_LEVELS > 4, the pgtable_l5_enabled() may not be true. For example, in arm64: #if CONFIG_PGTABLE_LEVELS > 4 static __always_inline bool pgtable_l5_enabled(void) { if (!alternative_has_cap_likely(ARM64_ALWAYS_BOOT)) return vabits_actual == VA_BITS; return alternative_has_cap_unlikely(ARM64_HAS_VA52); } Did I miss something? My patch series is not only for cleanup, but also for fixes of UAF issue [1], so is it possible to rebase your patch series onto mine? I can post v3 ASAP. [1]. https://lore.kernel.org/all/67548279.050a0220.a30f1.015b.GAE@google.com/ Thanks! > > Let me know if that makes sense, if so I'll post a v2. > > Cheers, > - Kevin