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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 3D082E7E0BA for ; Mon, 9 Feb 2026 09:54:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=IrDoYLyiC3yn1nM6rKNC2iEmkXxrMHxQFeD9sl87gjA=; b=o/rqv7BHIofEsO33pex2sAoi+Q Sc9n0nuUVCRbQOqydPVSNFqlh2Qs5Bwi81nTfYqHlm9BUrAieR+tiu5GIypAydUyb6PlDJ6Wm/YBn Oi4d0P29Yu1JkdTFgvnVCZPl2tz214A9eajS85NJbOVi5JrjZdmsnTRz6y6B+E6f9ZplaQ6OTq7zi IhD/2IIgGa6r56v8yOzm2W6scKrWtD29fICR3mWlD2XlC3muXp2Lq/gUChmB8RcQbDwkEHjkLoduG tw1l2RCmuaVddG2tSg+CnVrBRhRGlg6ABMiq2F98odOoPAsgz55XjXp0tXO+B13YwmEUmUif6o+J9 AgAanUyw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vpNyc-0000000FBsp-0ooF; Mon, 09 Feb 2026 09:54:42 +0000 Received: from tor.source.kernel.org ([2600:3c04:e001:324:0:1991:8:25]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1vpNya-0000000FBsA-14hU for linux-arm-kernel@lists.infradead.org; Mon, 09 Feb 2026 09:54:40 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id 1E94B600B0; Mon, 9 Feb 2026 09:54:39 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 96E69C116C6; Mon, 9 Feb 2026 09:54:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1770630878; bh=3tBHDDvBJjbjVnORXt//tsMxH53+PSsCsTP84KGDkeY=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=ArfQZAocn3bNOTGiysPVyOMe587mUPIZxvyXEE2Xhmcgglt7QoDFMi/M9Nnt6wohk NZz+f8NBf1if+1TK9UQz0R+uY005AH8rYmZJ1LVKkvfd3l1qkxuPW78axr7gpZDBFH unUm/P6Pn1tIvbeUobFDZLSk0Na8iGT96+hqTFrtI81ETKk24v5akjOiN5K/0AjD5x rI5UN5k8mVbb6/owKbo4OdpIsSyd/dpXw9HnhaVopbDBBZqI93jE3ObIL9nkmGkUsC AZbFx67KRYSxPSVl7oipYgkgroohTjeJP63MEAOZHaaK1Pgn601KvrBFay8s6kkfU2 Z28pnDyucyYaw== Message-ID: Date: Mon, 9 Feb 2026 10:54:29 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm: rmap: skip batched unmapping for UFFD vmas To: Baolin Wang Cc: Liam.Howlett@oracle.com, akpm@linux-foundation.org, baohua@kernel.org, catalin.marinas@arm.com, dev.jain@arm.com, harry.yoo@oracle.com, jannh@google.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, lorenzo.stoakes@oracle.com, mhocko@suse.com, riel@surriel.com, rppt@kernel.org, ryan.roberts@arm.com, surenb@google.com, vbabka@suse.cz, will@kernel.org, willy@infradead.org References: <142919ac14d3cf70cba370808d85debe089df7b4.1766631066.git.baolin.wang@linux.alibaba.com> <20260116162652.176054-1-baolin.wang@linux.alibaba.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 1/16/26 17:26, Baolin Wang wrote: > As Dev reported[1], it's not ready to support batched unmapping for uffd case. > Let's still fallback to per-page unmapping for the uffd case. > > [1] https://lore.kernel.org/linux-mm/20260116082721.275178-1-dev.jain@arm.com/ > Reported-by: Dev Jain > Suggested-by: Barry Song > Signed-off-by: Baolin Wang > --- > mm/rmap.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/mm/rmap.c b/mm/rmap.c > index f13480cb9f2e..172643092dcf 100644 > --- a/mm/rmap.c > +++ b/mm/rmap.c > @@ -1953,6 +1953,9 @@ static inline unsigned int folio_unmap_pte_batch(struct folio *folio, > if (pte_unused(pte)) > return 1; > > + if (userfaultfd_wp(vma)) > + return 1; > + Interesting. I was just wondering why we didn't run into that with lazyfree folios. Staring at pte_install_uffd_wp_if_needed(), we never set the marker for anonymous VMAs. So, yeah, if one sets lazyfree on a uffd-wp PTE, the uffd-wp bit will just get zapped alongside. Just like MADV_DONTNEED. I'm fine with that temporary fix. But I guess the non-hacky way to handle this would be: From 53d016d6e6f624425dbdbc2fb1dec7c91fbef15c Mon Sep 17 00:00:00 2001 From: "David Hildenbrand (Arm)" Date: Mon, 9 Feb 2026 10:52:59 +0100 Subject: [PATCH] tmp Signed-off-by: David Hildenbrand (Arm) --- include/linux/mm_inline.h | 15 ++++++--------- mm/memory.c | 21 +-------------------- mm/rmap.c | 2 +- 3 files changed, 8 insertions(+), 30 deletions(-) diff --git a/include/linux/mm_inline.h b/include/linux/mm_inline.h index fa2d6ba811b5..8a9a2c5f5ee3 100644 --- a/include/linux/mm_inline.h +++ b/include/linux/mm_inline.h @@ -566,9 +566,8 @@ static inline pte_marker copy_pte_marker( * * Returns true if an uffd-wp pte was installed, false otherwise. */ -static inline bool -pte_install_uffd_wp_if_needed(struct vm_area_struct *vma, unsigned long addr, - pte_t *pte, pte_t pteval) +static inline bool install_uffd_wp_ptes_if_needed(struct vm_area_struct *vma, + unsigned long addr, pte_t *pte, unsigned int nr, pte_t pteval) { bool arm_uffd_pte = false; @@ -598,13 +597,11 @@ pte_install_uffd_wp_if_needed(struct vm_area_struct *vma, unsigned long addr, if (unlikely(pte_swp_uffd_wp_any(pteval))) arm_uffd_pte = true; - if (unlikely(arm_uffd_pte)) { - set_pte_at(vma->vm_mm, addr, pte, - make_pte_marker(PTE_MARKER_UFFD_WP)); - return true; - } + if (likely(!arm_uffd_pte)) + return false; - return false; + set_ptes(vma->vm_mm, addr, pte, make_pte_marker(PTE_MARKER_UFFD_WP), nr); + return true; } static inline bool vma_has_recency(const struct vm_area_struct *vma) diff --git a/mm/memory.c b/mm/memory.c index da360a6eb8a4..0a87d02a9a69 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1592,29 +1592,10 @@ zap_install_uffd_wp_if_needed(struct vm_area_struct *vma, unsigned long addr, pte_t *pte, int nr, struct zap_details *details, pte_t pteval) { - bool was_installed = false; - - if (!uffd_supports_wp_marker()) - return false; - - /* Zap on anonymous always means dropping everything */ - if (vma_is_anonymous(vma)) - return false; - if (zap_drop_markers(details)) return false; - for (;;) { - /* the PFN in the PTE is irrelevant. */ - if (pte_install_uffd_wp_if_needed(vma, addr, pte, pteval)) - was_installed = true; - if (--nr == 0) - break; - pte++; - addr += PAGE_SIZE; - } - - return was_installed; + return install_uffd_wp_ptes_if_needed(vma, addr, pte, nr, pteval); } static __always_inline void zap_present_folio_ptes(struct mmu_gather *tlb, diff --git a/mm/rmap.c b/mm/rmap.c index 7b9879ef442d..f71aacf35925 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -2061,7 +2061,7 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma, * we may want to replace a none pte with a marker pte if * it's file-backed, so we don't lose the tracking info. */ - pte_install_uffd_wp_if_needed(vma, address, pvmw.pte, pteval); + install_uffd_wp_ptes_if_needed(vma, address, pvmw.pte, nr_pages, pteval); /* Update high watermark before we lower rss */ update_hiwater_rss(mm); -- 2.43.0 Does somebody have time to look into that? We should also adjust the doc of pte_install_uffd_wp_if_needed() and turn it into some proper kerneldoc. -- Cheers, David