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 3A8BAC5DF94 for ; Mon, 24 Aug 2026 14:59:38 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 2789F6B008C; Mon, 24 Aug 2026 10:59:37 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 24F396B0092; Mon, 24 Aug 2026 10:59:37 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 164E56B0096; Mon, 24 Aug 2026 10:59:37 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id D681A6B008C for ; Mon, 24 Aug 2026 10:59:36 -0400 (EDT) Received: from smtpin02.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay09.hostedemail.com (Postfix) with ESMTP id 6559180178 for ; Mon, 24 Aug 2026 14:59:36 +0000 (UTC) X-FDA: 85136471952.02.C17AF34 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf26.hostedemail.com (Postfix) with ESMTP id C107C14000D for ; Mon, 24 Aug 2026 14:59:34 +0000 (UTC) Authentication-Results: imf26.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=WGFVkLHL; spf=pass (imf26.hostedemail.com: domain of ljs@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=ljs@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=1787583574; 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-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=AccNNgKH6mpdiOZn+TQ6yi+YTRFl1ckABXXlP5qNp0s=; b=UvubDwMJ6Vt1nUF0mXaHLN2hGcs+S2nRqIbrikglmYF8/IoedgluIas45heeSx8LGF/bKN gxvbYAKePWm9hJm/5Rx4vs3jW+RW5qjRriF0Flpn7tL5i/N5yZqKoDWcqI4rk/XSXUGuxM haiGjYnzpJEMMZDBsmJrOlF/cf8fl+I= ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1787583574; b=euKLb74p2QJ0Bw+1ii5antwDijYs7yjkLRCaE+NgPomRSQu3/chJGUqw+7plK5P7fAGpsW cWSWeDMBr1UzNmfFtNPbBr5jIjSt9/+fsfEEpvVB17dqm/mMdJehTZ9k8DadIjlTFeQkDG Eou19QLKLk5QO1ZgiSDscig92ys1lrg= ARC-Authentication-Results: i=1; imf26.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=WGFVkLHL; spf=pass (imf26.hostedemail.com: domain of ljs@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=ljs@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 4C5FD600CB; Mon, 24 Aug 2026 14:59:34 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7E2CC1F000E9; Mon, 24 Aug 2026 14:59:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1787583574; bh=AccNNgKH6mpdiOZn+TQ6yi+YTRFl1ckABXXlP5qNp0s=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=WGFVkLHLt8glwJyNyzpbegLiEczgB3KRRpoxrsKbnYBufxLJsdfqDhjhdP7T16Tx5 bqxKzSNDAJCPhN/X/3zf+HiOu+g0MnTXFumI1OQd9LYWSCC54AQS8bvMlvM7Q7DEdB F6+Y9XiTmfKwR+wo5sGnM0dgZnSkFBQxie7k+L7q0HtnN0kovChN6zZm2ic4jGevda Hkd+WMr6ZxnA/yTIZcDJL8LfULRtlUE+8UlWLZyr4gIuAu5E7JTeg9qNc7tLpPrH+L z5FuXi7SjxSz37zwDb/a62Uf6rEkWJgcBNM1Kin4Iwuk7WW72JJ2lAu6X7xGJJIEi9 2kVhcK32BgG3Q== Date: Mon, 24 Aug 2026 15:59:26 +0100 From: "Lorenzo Stoakes (ARM)" To: "Mike Rapoport (Microsoft)" Cc: Andrew Morton , David Hildenbrand , Baolin Wang , Barry Song , Dev Jain , Hugh Dickins , Jann Horn , Jason Gunthorpe , John Hubbard , Jonathan Corbet , Lance Yang , "Liam R. Howlett" , Masami Hiramatsu , Mathieu Desnoyers , Michal Hocko , Muchun Song , Nico Pache , Oscar Salvador , Pedro Falcato , Peter Xu , Ryan Roberts , Shakeel Butt , Shuah Khan , Steven Rostedt , Suren Baghdasaryan , Usama Arif , Vlastimil Babka , Zi Yan , linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-trace-kernel@vger.kernel.org Subject: Re: [PATCH 1/6] mm/gup: move gup_can_follow_protnone() to gup.c Message-ID: References: <20260823-uffd-vm-flags-v1-v1-0-3086981b33cf@kernel.org> <20260823-uffd-vm-flags-v1-v1-1-3086981b33cf@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260823-uffd-vm-flags-v1-v1-1-3086981b33cf@kernel.org> X-Rspam-User: X-Stat-Signature: kqpm7pawg6e39y9uodi8q1iezadz8d8w X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: C107C14000D X-HE-Tag: 1787583574-600918 X-HE-Meta: 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 NQLPNfbk oRVnX0GhoeUBczO9N1oTFBN31DBVDPIVo2vIu/S07QCxTe1o2PKW09wmu6Xp3f7Tp0QpOO2ogMo3+0gavxJ1f7dUdS3fJA2hZfdpHx1mXKZt8QPSyiQz0wBPPTxw9jhJtcSptCZ7FvpclP8J5epHZVIgDY0Mzf/uQARkWsqtky3LCzXKdNo46vBD6tjRP0S+OZe69EF4NKWds+pMqUevxDs6e+3JzLZ21s+WcfEkggwt1u0jpXaKbiUgnCI3YEfUPAezT/uHBhiebC64nlKYJkyTM6z5GZxgDwAspgIcFOiAhPvhBEB9SKPOEw2ZC8bBy6Nrw Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Sun, Aug 23, 2026 at 03:17:38PM +0300, Mike Rapoport (Microsoft) wrote: > gup_can_follow_protnone() is defined in include/linux/mm.h but only used > by mm/gup.c. > > First, there is no reason to have it in already gigantic header. > > Next, the upcoming refactoring of userfaultfd flags will make > gup_can_follow_protnone() depend on userfaultfd_k.h which would cause a > cyclic header dependency. > > Move gup_can_follow_protnone() to mm/gup.c. > > No functional change. > > Assisted-by: copilot:claude-opus-5 > Signed-off-by: Mike Rapoport (Microsoft) LGTM so: Reviewed-by: Lorenzo Stoakes (ARM) > --- > include/linux/mm.h | 38 -------------------------------------- > mm/gup.c | 38 ++++++++++++++++++++++++++++++++++++++ > 2 files changed, 38 insertions(+), 38 deletions(-) > > diff --git a/include/linux/mm.h b/include/linux/mm.h > index 0829e0d3b2d1..4daf9cd6ae8e 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -4860,44 +4860,6 @@ static inline int vm_fault_to_errno(vm_fault_t vm_fault, int foll_flags) > return 0; > } > > -/* > - * Indicates whether GUP can follow a PROT_NONE mapped page, or whether > - * a (NUMA hinting or userfaultfd RWP) fault is required. > - */ > -static inline bool gup_can_follow_protnone(const struct vm_area_struct *vma, > - unsigned int flags) > -{ > - /* > - * VM_UFFD_RWP uses protnone as an access-tracking marker, not for > - * NUMA hinting. GUP must always take a fault so the access is > - * delivered to userfaultfd, regardless of FOLL_HONOR_NUMA_FAULT. > - * > - * Only do so while the VMA is accessible. If it has been made > - * inaccessible (e.g. mprotect(PROT_NONE)), fall through to the guard > - * below: forcing a fault there would loop, as handle_mm_fault() makes > - * no progress on protnone in an inaccessible VMA, and the access is > - * denied regardless of RWP anyway. > - */ > - if (vma_test_single_mask(vma, VMA_UFFD_RWP) && vma_is_accessible(vma)) > - return false; > - > - /* > - * If callers don't want to honor NUMA hinting faults, no need to > - * determine if we would actually have to trigger a NUMA hinting fault. > - */ > - if (!(flags & FOLL_HONOR_NUMA_FAULT)) > - return true; > - > - /* > - * NUMA hinting faults don't apply in inaccessible (PROT_NONE) VMAs. > - * > - * Requiring a fault here even for inaccessible VMAs would mean that > - * FOLL_FORCE cannot make any progress, because handle_mm_fault() > - * refuses to process NUMA hinting faults in inaccessible VMAs. > - */ > - return !vma_is_accessible(vma); > -} > - > typedef int (*pte_fn_t)(pte_t *pte, unsigned long addr, void *data); > extern int apply_to_page_range(struct mm_struct *mm, unsigned long address, > unsigned long size, pte_fn_t fn, void *data); > diff --git a/mm/gup.c b/mm/gup.c > index eb898ea1ee22..500e2aa99e48 100644 > --- a/mm/gup.c > +++ b/mm/gup.c > @@ -633,6 +633,44 @@ static struct page *no_page_table(struct vm_area_struct *vma, > return NULL; > } > > +/* > + * Indicates whether GUP can follow a PROT_NONE mapped page, or whether > + * a (NUMA hinting or userfaultfd RWP) fault is required. > + */ > +static inline bool gup_can_follow_protnone(const struct vm_area_struct *vma, > + unsigned int flags) > +{ > + /* > + * VM_UFFD_RWP uses protnone as an access-tracking marker, not for > + * NUMA hinting. GUP must always take a fault so the access is > + * delivered to userfaultfd, regardless of FOLL_HONOR_NUMA_FAULT. > + * > + * Only do so while the VMA is accessible. If it has been made > + * inaccessible (e.g. mprotect(PROT_NONE)), fall through to the guard > + * below: forcing a fault there would loop, as handle_mm_fault() makes > + * no progress on protnone in an inaccessible VMA, and the access is > + * denied regardless of RWP anyway. > + */ > + if (vma_test_single_mask(vma, VMA_UFFD_RWP) && vma_is_accessible(vma)) > + return false; > + > + /* > + * If callers don't want to honor NUMA hinting faults, no need to > + * determine if we would actually have to trigger a NUMA hinting fault. > + */ > + if (!(flags & FOLL_HONOR_NUMA_FAULT)) > + return true; > + > + /* > + * NUMA hinting faults don't apply in inaccessible (PROT_NONE) VMAs. > + * > + * Requiring a fault here even for inaccessible VMAs would mean that > + * FOLL_FORCE cannot make any progress, because handle_mm_fault() > + * refuses to process NUMA hinting faults in inaccessible VMAs. > + */ > + return !vma_is_accessible(vma); > +} > + > #ifdef CONFIG_PGTABLE_HAS_HUGE_LEAVES > /* FOLL_FORCE can write to even unwritable PUDs in COW mappings. */ > static inline bool can_follow_write_pud(pud_t pud, struct page *page, > > -- > 2.53.0 > -- Cheers, Lorenzo