From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 8F533FCC046 for ; Fri, 6 Mar 2026 17:19:25 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id F2A306B00A6; Fri, 6 Mar 2026 12:19:24 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id ED4556B00B7; Fri, 6 Mar 2026 12:19:24 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id DC3A86B00B9; Fri, 6 Mar 2026 12:19:24 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id C963D6B00A6 for ; Fri, 6 Mar 2026 12:19:24 -0500 (EST) Received: from smtpin14.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id 932A6BA5D1 for ; Fri, 6 Mar 2026 17:19:24 +0000 (UTC) X-FDA: 84516299448.14.06009BD Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf13.hostedemail.com (Postfix) with ESMTP id 00B182000D for ; Fri, 6 Mar 2026 17:19:22 +0000 (UTC) Authentication-Results: imf13.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=uG7uATZ5; spf=pass (imf13.hostedemail.com: domain of rppt@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=rppt@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1772817563; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=Z+/JJD6szHlucDGmeEEd5/2gx+MQ+OLm1xs2AchaAjo=; b=RCuZkso1hpqcr0u5MpoI0nuXFurwB68PhagJJ+u+6//nrjeWOVxm9z1017Yv5fVEFt8Ryb 0uJ+woWO7ua8qrS1XgThtLrBFAfnrUARAbSuE0v23qLuA7PQ5kS21SMcBcNY6sHEtINWyJ lAS4P0T3MrE9d5Gu04fb1efImvb8DME= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1772817563; a=rsa-sha256; cv=none; b=oBT9zI5UL6WLgN/fNJLVWJf27E5mfN7pj8EyZcGjWCFQJu3Fx6jqKyH/XE23m5MEOwebMt 1szT4BHGqLU4+W+3ojkvHvmKrahWJzkpAlfAmREFBPa2MB2l5+M4du7W29vroCvZMVyHuG T62RuD+r2kJtYlG6KwjunJtcvF9tx2Y= ARC-Authentication-Results: i=1; imf13.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=uG7uATZ5; spf=pass (imf13.hostedemail.com: domain of rppt@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=rppt@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id 7E0F060053; Fri, 6 Mar 2026 17:19:22 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7CD11C4CEF7; Fri, 6 Mar 2026 17:19:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772817562; bh=gidwe1JDFVRvjF4HHZQP+Up45bV0zxpQn7GX5nnMwuI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=uG7uATZ5bBIgEOK0p125XokCc9P2sskQdk5BkZ/aYHwXO5FcYeCCVi370RwcFDozA 8ioSXRz1nLl7+49RynTI5/DazMkdsyku6wbfT5VRvIblvYeh2TVXUqLpKeNbbNHk5b 0hclBvWDAxLWj4uHKksnB+9SCahwhy7HXf0kT5qNxaeEPyHD3bYSwOtaAGVa1UisF4 s9sS2ZLiw++pf8MQE2EEub9QOqfl5Wd7BejU/H6PHnKpgpQZuVaZ+Aj3lKNMBfO/jw F3dmC2FIaDhzjTqG3tnqz6poh5ppJoXRSn1Lnw/in8UNYZruk1QqlOt9QG4kRcXh+p TOZ4kGajFXh1A== From: Mike Rapoport To: Andrew Morton Cc: Andrea Arcangeli , Axel Rasmussen , Baolin Wang , David Hildenbrand , Hugh Dickins , James Houghton , "Liam R. Howlett" , Lorenzo Stoakes , "Matthew Wilcox (Oracle)" , Michal Hocko , Mike Rapoport , Muchun Song , Nikita Kalyazin , Oscar Salvador , Paolo Bonzini , Peter Xu , Sean Christopherson , Shuah Khan , Suren Baghdasaryan , Vlastimil Babka , kvm@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH v2 09/15] userfaultfd: introduce vm_uffd_ops->alloc_folio() Date: Fri, 6 Mar 2026 19:18:09 +0200 Message-ID: <20260306171815.3160826-10-rppt@kernel.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260306171815.3160826-1-rppt@kernel.org> References: <20260306171815.3160826-1-rppt@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Stat-Signature: nks9rc4c5isoe8519ir1yu81sqasnrmy X-Rspam-User: X-Rspamd-Queue-Id: 00B182000D X-Rspamd-Server: rspam12 X-HE-Tag: 1772817562-844380 X-HE-Meta: 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 0UVu5o0l gb1QAtcO/W1vNsBXoGkuZPOHm2hjxJedn5lgVXaWUTIVn5KMAVzHDj7v5Lz9SDDjzN7PMziEhCO3CfiSv5C6btLKmKOTIxrn8w+DARMW/xCRHyx0DPbtgLydjvaD4OVqgBy+LkFufwqL+FwNxC0eGRVHMLLUar6kVXRnfIgCrnORTQv/bZq7XwIl+kFJJCbW5lY7hLdfRkiuwe80WrtzIwcfp2g61gHI0dXdeKxA6w/tKbGonUq/5XcRBbkr9dPKCds6l740S17g98IGBK0/EjezqUg== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: From: "Mike Rapoport (Microsoft)" and use it to refactor mfill_atomic_pte_zeroed_folio() and mfill_atomic_pte_copy(). mfill_atomic_pte_zeroed_folio() and mfill_atomic_pte_copy() perform almost identical actions: * allocate a folio * update folio contents (either copy from userspace of fill with zeros) * update page tables with the new folio Split a __mfill_atomic_pte() helper that handles both cases and uses newly introduced vm_uffd_ops->alloc_folio() to allocate the folio. Pass the ops structure from the callers to __mfill_atomic_pte() to later allow using anon_uffd_ops for MAP_PRIVATE mappings of file-backed VMAs. Note, that the new ops method is called alloc_folio() rather than folio_alloc() to avoid clash with alloc_tag macro folio_alloc(). Signed-off-by: Mike Rapoport (Microsoft) --- include/linux/userfaultfd_k.h | 6 +++ mm/userfaultfd.c | 92 ++++++++++++++++++----------------- 2 files changed, 54 insertions(+), 44 deletions(-) diff --git a/include/linux/userfaultfd_k.h b/include/linux/userfaultfd_k.h index 66dfc3c164e6..4d8b879eed91 100644 --- a/include/linux/userfaultfd_k.h +++ b/include/linux/userfaultfd_k.h @@ -91,6 +91,12 @@ struct vm_uffd_ops { * The returned folio is locked and with reference held. */ struct folio *(*get_folio_noalloc)(struct inode *inode, pgoff_t pgoff); + /* + * Called during resolution of UFFDIO_COPY request. + * Should return allocate a and return folio or NULL if allocation fails. + */ + struct folio *(*alloc_folio)(struct vm_area_struct *vma, + unsigned long addr); }; /* A combined operation mode + behavior flags. */ diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index 98ade14eaa5b..31f3ab6a73e2 100644 --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -42,8 +42,26 @@ static bool anon_can_userfault(struct vm_area_struct *vma, vm_flags_t vm_flags) return true; } +static struct folio *anon_alloc_folio(struct vm_area_struct *vma, + unsigned long addr) +{ + struct folio *folio = vma_alloc_folio(GFP_HIGHUSER_MOVABLE, 0, vma, + addr); + + if (!folio) + return NULL; + + if (mem_cgroup_charge(folio, vma->vm_mm, GFP_KERNEL)) { + folio_put(folio); + return NULL; + } + + return folio; +} + static const struct vm_uffd_ops anon_uffd_ops = { .can_userfault = anon_can_userfault, + .alloc_folio = anon_alloc_folio, }; static const struct vm_uffd_ops *vma_uffd_ops(struct vm_area_struct *vma) @@ -458,7 +476,8 @@ static int mfill_copy_folio_retry(struct mfill_state *state, struct folio *folio return 0; } -static int mfill_atomic_pte_copy(struct mfill_state *state) +static int __mfill_atomic_pte(struct mfill_state *state, + const struct vm_uffd_ops *ops) { unsigned long dst_addr = state->dst_addr; unsigned long src_addr = state->src_addr; @@ -466,16 +485,12 @@ static int mfill_atomic_pte_copy(struct mfill_state *state) struct folio *folio; int ret; - folio = vma_alloc_folio(GFP_HIGHUSER_MOVABLE, 0, state->vma, dst_addr); + folio = ops->alloc_folio(state->vma, state->dst_addr); if (!folio) return -ENOMEM; - ret = -ENOMEM; - if (mem_cgroup_charge(folio, state->vma->vm_mm, GFP_KERNEL)) - goto out_release; - - ret = mfill_copy_folio_locked(folio, src_addr); - if (unlikely(ret)) { + if (uffd_flags_mode_is(flags, MFILL_ATOMIC_COPY)) { + ret = mfill_copy_folio_locked(folio, src_addr); /* * Fallback to copy_from_user outside mmap_lock. * If retry is successful, mfill_copy_folio_locked() returns @@ -483,9 +498,15 @@ static int mfill_atomic_pte_copy(struct mfill_state *state) * If there was an error, we must mfill_put_vma() anyway and it * will take care of unlocking if needed. */ - ret = mfill_copy_folio_retry(state, folio); - if (ret) - goto out_release; + if (unlikely(ret)) { + ret = mfill_copy_folio_retry(state, folio); + if (ret) + goto err_folio_put; + } + } else if (uffd_flags_mode_is(flags, MFILL_ATOMIC_ZEROPAGE)) { + clear_user_highpage(&folio->page, state->dst_addr); + } else { + VM_WARN_ONCE(1, "unknown UFFDIO operation"); } /* @@ -498,47 +519,30 @@ static int mfill_atomic_pte_copy(struct mfill_state *state) ret = mfill_atomic_install_pte(state->pmd, state->vma, dst_addr, &folio->page, true, flags); if (ret) - goto out_release; -out: - return ret; -out_release: + goto err_folio_put; + + return 0; + +err_folio_put: + folio_put(folio); /* Don't return -ENOENT so that our caller won't retry */ if (ret == -ENOENT) ret = -EFAULT; - folio_put(folio); - goto out; + return ret; } -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) @@ -551,7 +555,7 @@ 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); _dst_pte = pte_mkspecial(pfn_pte(my_zero_pfn(dst_addr), dst_vma->vm_page_prot)); -- 2.51.0