From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id A731564 for ; Tue, 14 Apr 2026 05:47:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776145630; cv=none; b=EOSMV0ZyairRzAWV2A8lV+dbwYc7DXnGU7WvdLVRKraZiayJcQdz4J9QMaNXoi4WRybdz60RABac50sXJRAXjzcRhjMuaKRjwgyi8ULuAfHOUvFPttI0vhLuBj9iwo2a5yQWS9jLpxTyilP21Vpg0FStynercI3gHB9oFNLv9Yg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776145630; c=relaxed/simple; bh=W5wCrGEAWO8HkuC+xu/FnjB1AdfwSJhUSgv1NRa0lT4=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=gLJo/xgF+jB2uJyt0tU8woekrwwQSZQS8E2OSO9u/n38AJI2cUpOBgFrXSwh8DFrYyRWaKpV6Uzx6YFQxhV2he9EVAXDWrNFmGAECVK2G/WFtiVxED8u8ggRdbVMrSKNyNcgmZArU1855kee1xPmBdGNhPHLXVq7TEpYHSw9wo4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b=iQBMeGi6; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b="iQBMeGi6" Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 3C8BF4EE4; Mon, 13 Apr 2026 22:47:02 -0700 (PDT) Received: from [10.164.148.48] (MacBook-Pro.blr.arm.com [10.164.148.48]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 052E03F7B4; Mon, 13 Apr 2026 22:46:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1776145627; bh=W5wCrGEAWO8HkuC+xu/FnjB1AdfwSJhUSgv1NRa0lT4=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=iQBMeGi6YLTp229qB+PhAAChcuBCNiAg0FSXJ5oi3l3Jbh7cM9Szog/JUl5Aw/gV/ ANM37lILc0V+iubwGtRf328rlhldqM3Pma5hY2wU6Mbc54BN1XzQohgru0rjn0HCcJ zAyv3x1OBU1F7rr2RGbPG0x6V4Fuh4NXMj5acKII= Message-ID: Date: Tue, 14 Apr 2026 11:16:54 +0530 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 4/9] mm/memory: Batch set uffd-wp markers during zapping To: akpm@linux-foundation.org, david@kernel.org, hughd@google.com, chrisl@kernel.org Cc: ljs@kernel.org, Liam.Howlett@oracle.com, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, kasong@tencent.com, qi.zheng@linux.dev, shakeel.butt@linux.dev, baohua@kernel.org, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, riel@surriel.com, harry@kernel.org, jannh@google.com, pfalcato@suse.de, baolin.wang@linux.alibaba.com, shikemeng@huaweicloud.com, nphamcs@gmail.com, bhe@redhat.com, youngjun.park@lge.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, ryan.roberts@arm.com, anshuman.khandual@arm.com References: <20260410103204.120409-1-dev.jain@arm.com> <20260410103204.120409-5-dev.jain@arm.com> Content-Language: en-US From: Dev Jain In-Reply-To: <20260410103204.120409-5-dev.jain@arm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 10/04/26 4:01 pm, Dev Jain wrote: > In preparation for the next patch, enable batch setting of uffd-wp ptes. > > The code paths passing nr > 1 to zap_install_uffd_wp_if_needed() produce > that nr through either folio_pte_batch or swap_pte_batch, guaranteeing that > all ptes are the same w.r.t belonging to the same type of VMA (anonymous > or non-anonymous, wp-armed or non-wp-armed), and all being marked with > uffd-wp or all being not marked. > > Note that we will have to use set_pte_at() in a loop instead of set_ptes() > since the latter cannot handle present->non-present conversion for > nr_pages > 1. > > Convert documentation of install_uffd_wp_ptes_if_needed to kerneldoc > format. > > No functional change is intended. > > Signed-off-by: Dev Jain > --- > include/linux/mm_inline.h | 32 ++++++++++++++++++++------------ > mm/memory.c | 20 +------------------- > mm/rmap.c | 2 +- > 3 files changed, 22 insertions(+), 32 deletions(-) > > diff --git a/include/linux/mm_inline.h b/include/linux/mm_inline.h > index a171070e15f05..20c34d14ad539 100644 > --- a/include/linux/mm_inline.h > +++ b/include/linux/mm_inline.h > @@ -566,9 +566,17 @@ static inline pte_marker copy_pte_marker( > return dstm; > } > > -/* > - * If this pte is wr-protected by uffd-wp in any form, arm the special pte to > - * replace a none pte. NOTE! This should only be called when *pte is already > +/** > + * install_uffd_wp_ptes_if_needed - install uffd-wp marker on PTEs that map > + * consecutive pages of the same large folio. > + * @vma: The VMA the pages are mapped into. > + * @addr: Address the first page of this batch is mapped at. > + * @ptep: Page table pointer for the first entry of this batch. > + * @pteval: old value of the entry pointed to by ptep. > + * @nr_ptes: Number of entries to clear (batch size). > + * > + * If the ptes were wr-protected by uffd-wp in any form, arm special ptes to > + * replace none ptes. NOTE! This should only be called when *pte is already > * cleared so we will never accidentally replace something valuable. Meanwhile > * none pte also means we are not demoting the pte so tlb flushed is not needed. > * E.g., when pte cleared the caller should have taken care of the tlb flush. > @@ -576,11 +584,11 @@ static inline pte_marker copy_pte_marker( > * Must be called with pgtable lock held so that no thread will see the none > * pte, and if they see it, they'll fault and serialize at the pgtable lock. > * > - * Returns true if an uffd-wp pte was installed, false otherwise. > + * Returns true if uffd-wp ptes were 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) > +install_uffd_wp_ptes_if_needed(struct vm_area_struct *vma, unsigned long addr, > + pte_t *pte, pte_t pteval, unsigned long nr_ptes) >From Sashiko - kernel doc mismatch. I'll rename pte to ptep. > { > bool arm_uffd_pte = false; > > @@ -610,13 +618,13 @@ 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; > + for (int i = 0; i < nr_ptes; ++i, ++pte, addr += PAGE_SIZE) > + set_pte_at(vma->vm_mm, addr, pte, make_pte_marker(PTE_MARKER_UFFD_WP)); > + > + 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 ea65685711311..eef144fa293d4 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -1594,29 +1594,11 @@ 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 install_uffd_wp_ptes_if_needed(vma, addr, pte, pteval, nr); > > - return was_installed; > } > > static __always_inline void zap_present_folio_ptes(struct mmu_gather *tlb, > diff --git a/mm/rmap.c b/mm/rmap.c > index fa5d6599dedf0..20e1fb81c33fc 100644 > --- a/mm/rmap.c > +++ b/mm/rmap.c > @@ -2263,7 +2263,7 @@ 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, pteval, 1); > > /* Update high watermark before we lower rss */ > update_hiwater_rss(mm);