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Mon, 02 Feb 2026 14:13:24 -0800 (PST) X-Received: by 2002:a05:622a:28d:b0:4ed:af59:9df0 with SMTP id d75a77b69052e-505d228ac43mr152974231cf.40.1770070403763; Mon, 02 Feb 2026 14:13:23 -0800 (PST) Received: from x1.local ([142.188.210.156]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-50489d1b52csm101407911cf.8.2026.02.02.14.13.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 02 Feb 2026 14:13:23 -0800 (PST) Date: Mon, 2 Feb 2026 17:13:20 -0500 From: Peter Xu To: Mike Rapoport Cc: linux-mm@kvack.org, Andrea Arcangeli , Andrew Morton , Axel Rasmussen , Baolin Wang , David Hildenbrand , Hugh Dickins , James Houghton , "Liam R. Howlett" , Lorenzo Stoakes , Michal Hocko , Muchun Song , Nikita Kalyazin , Oscar Salvador , Paolo Bonzini , Sean Christopherson , Shuah Khan , Suren Baghdasaryan , Vlastimil Babka , linux-kernel@vger.kernel.org, kvm@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: Re: [PATCH RFC 09/17] userfaultfd: introduce vm_uffd_ops->alloc_folio() Message-ID: References: <20260127192936.1250096-1-rppt@kernel.org> <20260127192936.1250096-10-rppt@kernel.org> MIME-Version: 1.0 In-Reply-To: <20260127192936.1250096-10-rppt@kernel.org> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: s6jRvx0OXZe2taHgNebDXPJBJj3HuxEpHz25bZLgiR8_1770070404 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: B3A59C000C X-Stat-Signature: hjy76ixkparyjz1fabzyf613449t8rh8 X-Rspam-User: X-HE-Tag: 1770070406-620611 X-HE-Meta: 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 R+KVu07c /nWea7G0B5gIkG20l1yItY3RGzhnxoOQSS86y83j0rcTAeGMcIvGc3Be2C0v7hSJTik3j7RGqKbRpggsXncj8cW66efKoa9wu6lvOpNwgJYvmp7eFe15EIzumViSxcMnPLCOkWvQOOozbVWkS+BhLJEZC26XElAFu1j1l8ERbSp8rAx9yobq8vhQ1ypm7M0feIgworND/x4JBb3iI5UWXyN9Zkw+dORZs0lVLOZFDThP1G4WdhMj6ZNhxDCTJwHWkYCUbU8Khx6jdHt764iZF/GbXN7M31YsR6BAUyGbubt++Fok0ciZqauiqYRvmJRn6uDVK/4D8oghoLS9BYwVYiVipcabwGRGEDJ3U54g2Dv6z89aoIeuXcoe4Id+maSWFyq9uORWdoX8oFs/ZBRCh/XE86NibzAqj8bgoUPpdF+ogsAJvffD2tTjsyQ== 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 Tue, Jan 27, 2026 at 09:29:28PM +0200, Mike Rapoport wrote: [...] > -static int mfill_atomic_pte_zeroed_folio(pmd_t *dst_pmd, > - struct vm_area_struct *dst_vma, > - unsigned long dst_addr) > +static int mfill_atomic_pte_copy(struct mfill_state *state) > { > - struct folio *folio; > - int ret = -ENOMEM; > - > - folio = vma_alloc_zeroed_movable_folio(dst_vma, dst_addr); > - if (!folio) > - return ret; > - > - if (mem_cgroup_charge(folio, dst_vma->vm_mm, GFP_KERNEL)) > - goto out_put; > + const struct vm_uffd_ops *ops = vma_uffd_ops(state->vma); > > - /* > - * The memory barrier inside __folio_mark_uptodate makes sure that > - * zeroing out the folio become visible before mapping the page > - * using set_pte_at(). See do_anonymous_page(). > - */ > - __folio_mark_uptodate(folio); > + return __mfill_atomic_pte(state, ops); > +} > > - ret = mfill_atomic_install_pte(dst_pmd, dst_vma, dst_addr, > - &folio->page, true, 0); > - if (ret) > - goto out_put; > +static int mfill_atomic_pte_zeroed_folio(struct mfill_state *state) > +{ > + const struct vm_uffd_ops *ops = vma_uffd_ops(state->vma); > > - return 0; > -out_put: > - folio_put(folio); > - return ret; > + return __mfill_atomic_pte(state, ops); > } > > static int mfill_atomic_pte_zeropage(struct mfill_state *state) > @@ -542,7 +546,7 @@ static int mfill_atomic_pte_zeropage(struct mfill_state *state) > int ret; > > if (mm_forbids_zeropage(dst_vma->vm_mm)) > - return mfill_atomic_pte_zeroed_folio(dst_pmd, dst_vma, dst_addr); > + return mfill_atomic_pte_zeroed_folio(state); After this patch, mfill_atomic_pte_zeroed_folio() should be 100% the same impl with mfill_atomic_pte_copy(), so IIUC we can drop it. > > _dst_pte = pte_mkspecial(pfn_pte(my_zero_pfn(dst_addr), > dst_vma->vm_page_prot)); > -- > 2.51.0 > -- Peter Xu