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[99.254.121.117]) by smtp.gmail.com with ESMTPSA id af79cd13be357-7a3785d06fesm281331985a.1.2024.08.09.10.16.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 09 Aug 2024 10:16:54 -0700 (PDT) Date: Fri, 9 Aug 2024 13:16:51 -0400 From: Peter Xu To: David Hildenbrand Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Sean Christopherson , Oscar Salvador , Jason Gunthorpe , Axel Rasmussen , linux-arm-kernel@lists.infradead.org, x86@kernel.org, Will Deacon , Gavin Shan , Paolo Bonzini , Zi Yan , Andrew Morton , Catalin Marinas , Ingo Molnar , Alistair Popple , Borislav Petkov , Thomas Gleixner , kvm@vger.kernel.org, Dave Hansen , Alex Williamson , Yan Zhao Subject: Re: [PATCH 01/19] mm: Introduce ARCH_SUPPORTS_HUGE_PFNMAP and special bits to pmd/pud Message-ID: References: <20240809160909.1023470-1-peterx@redhat.com> <20240809160909.1023470-2-peterx@redhat.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: On Fri, Aug 09, 2024 at 06:34:15PM +0200, David Hildenbrand wrote: > On 09.08.24 18:08, Peter Xu wrote: > > This patch introduces the option to introduce special pte bit into > > pmd/puds. Archs can start to define pmd_special / pud_special when > > supported by selecting the new option. Per-arch support will be added > > later. > > > > Before that, create fallbacks for these helpers so that they are always > > available. > > > > Signed-off-by: Peter Xu > > --- > > include/linux/mm.h | 24 ++++++++++++++++++++++++ > > mm/Kconfig | 13 +++++++++++++ > > 2 files changed, 37 insertions(+) > > > > diff --git a/include/linux/mm.h b/include/linux/mm.h > > index 43b40334e9b2..90ca84200800 100644 > > --- a/include/linux/mm.h > > +++ b/include/linux/mm.h > > @@ -2644,6 +2644,30 @@ static inline pte_t pte_mkspecial(pte_t pte) > > } > > #endif > > +#ifndef CONFIG_ARCH_SUPPORTS_PMD_PFNMAP > > +static inline bool pmd_special(pmd_t pmd) > > +{ > > + return false; > > +} > > + > > +static inline pmd_t pmd_mkspecial(pmd_t pmd) > > +{ > > + return pmd; > > +} > > +#endif /* CONFIG_ARCH_SUPPORTS_PMD_PFNMAP */ > > + > > +#ifndef CONFIG_ARCH_SUPPORTS_PUD_PFNMAP > > +static inline bool pud_special(pud_t pud) > > +{ > > + return false; > > +} > > + > > +static inline pud_t pud_mkspecial(pud_t pud) > > +{ > > + return pud; > > +} > > +#endif /* CONFIG_ARCH_SUPPORTS_PUD_PFNMAP */ > > + > > #ifndef CONFIG_ARCH_HAS_PTE_DEVMAP > > static inline int pte_devmap(pte_t pte) > > { > > diff --git a/mm/Kconfig b/mm/Kconfig > > index 3936fe4d26d9..3db0eebb53e2 100644 > > --- a/mm/Kconfig > > +++ b/mm/Kconfig > > @@ -881,6 +881,19 @@ endif # TRANSPARENT_HUGEPAGE > > config PGTABLE_HAS_HUGE_LEAVES > > def_bool TRANSPARENT_HUGEPAGE || HUGETLB_PAGE > > +# TODO: Allow to be enabled without THP > > +config ARCH_SUPPORTS_HUGE_PFNMAP > > + def_bool n > > + depends on TRANSPARENT_HUGEPAGE > > + > > +config ARCH_SUPPORTS_PMD_PFNMAP > > + def_bool y > > + depends on ARCH_SUPPORTS_HUGE_PFNMAP && HAVE_ARCH_TRANSPARENT_HUGEPAGE > > + > > +config ARCH_SUPPORTS_PUD_PFNMAP > > + def_bool y > > + depends on ARCH_SUPPORTS_HUGE_PFNMAP && HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD > > + > > # > > # UP and nommu archs use km based percpu allocator > > # > > As noted in reply to other patches, I think you have to take care of > vm_normal_page_pmd() [if not done in another patch I am missing] and likely > you want to introduce vm_normal_page_pud(). So far this patch may not have direct involvement with vm_normal_page_pud() yet? Anyway, let's keep the discussion there, then we'll know how to move on. Thanks, -- Peter Xu