From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 67BB238E5D6 for ; Mon, 11 May 2026 07:37:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778485046; cv=none; b=s4TKpebOBA7mhRrsfEZ5GP8guMg4cMxn9TgwTq8Au0Z3J1IRaUDDs0kh8xxX1fHd+i0sC+oFSofnG+ZgMzs2FlltOFClERjzf5lNFaOPTX/KDdYeR1rIk1r6AgnMLbl1QblR9oDTMOmGkmWa68ZN5rhzpTGAD6a3kAO8KAiGlag= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778485046; c=relaxed/simple; bh=FpSA1WDpJHlS8rrqUpx43ZgyVTOLt4z5EwUNCLxqToM=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=Yop4AE0lKQdEnsAg80OtjZxFuSzqVvYNp/dIHBGB7/DEHOgySL7e7OnPfi9F8vsE60BbO/nYC8gTHPFUKj2UvCwdoVzq475ZmhCo++5y5MCv4iunLdkD6IiziKGTxwXeDuQTmH5BwZ0Vfy4FgT5uMWt/bpRGGw9eWGQAPvfheZY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=KaAXcaJ6; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="KaAXcaJ6" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 04A0FC2BCB0; Mon, 11 May 2026 07:37:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1778485045; bh=FpSA1WDpJHlS8rrqUpx43ZgyVTOLt4z5EwUNCLxqToM=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=KaAXcaJ6BrbJXKn+9jc5GcmuMc74/jrdsBILvtUqu9fOwO7XhNg9Uj2oF3EnXkZZi rNPcDcm/YL82VDA3zwXDVLfBD+jmEdHGa9oHtn2Cb/UEDXtIZZM+fJfapADXdxVIRQ PassE6RB8NTNHvmQMzzoXwk4hRkakrEfk40GklflCunk2D93yXOuQblNDHvQg0vfXN TmBsl3jpo5LERjZXJrNgbhVQO4qFxDyFrEezRgHO3pRJgxTadsr//PBins24D0YHBv Da7NWE/mmSblYQPTu6sL098oDYOZ1RFFb5A3VmARVZlVeT5sC8fYdEdpZEEMsLjUru BX2gD+9BO/zxg== Message-ID: <4b36ddb9-c11a-4320-85d4-3e059e67384f@kernel.org> Date: Mon, 11 May 2026 09:37:18 +0200 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 v3 4/9] mm/memory: Batch set uffd-wp markers during zapping To: Dev Jain , akpm@linux-foundation.org, ljs@kernel.org, hughd@google.com, chrisl@kernel.org, kasong@tencent.com Cc: riel@surriel.com, liam@infradead.org, vbabka@kernel.org, harry@kernel.org, jannh@google.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, qi.zheng@linux.dev, shakeel.butt@linux.dev, baohua@kernel.org, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, rppt@kernel.org, surenb@google.com, mhocko@suse.com, baolin.wang@linux.alibaba.com, shikemeng@huaweicloud.com, nphamcs@gmail.com, bhe@redhat.com, youngjun.park@lge.com, pfalcato@suse.de, ryan.roberts@arm.com, anshuman.khandual@arm.com References: <20260506094504.2588857-1-dev.jain@arm.com> <20260506094504.2588857-5-dev.jain@arm.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzS5EYXZpZCBIaWxk ZW5icmFuZCAoQ3VycmVudCkgPGRhdmlkQGtlcm5lbC5vcmc+wsGQBBMBCAA6AhsDBQkmWAik AgsJBBUKCQgCFgICHgUCF4AWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaYJt/AIZAQAKCRBN 3hD3AP+DWriiD/9BLGEKG+N8L2AXhikJg6YmXom9ytRwPqDgpHpVg2xdhopoWdMRXjzOrIKD g4LSnFaKneQD0hZhoArEeamG5tyo32xoRsPwkbpIzL0OKSZ8G6mVbFGpjmyDLQCAxteXCLXz ZI0VbsuJKelYnKcXWOIndOrNRvE5eoOfTt2XfBnAapxMYY2IsV+qaUXlO63GgfIOg8RBaj7x 3NxkI3rV0SHhI4GU9K6jCvGghxeS1QX6L/XI9mfAYaIwGy5B68kF26piAVYv/QZDEVIpo3t7 /fjSpxKT8plJH6rhhR0epy8dWRHk3qT5tk2P85twasdloWtkMZ7FsCJRKWscm1BLpsDn6EQ4 jeMHECiY9kGKKi8dQpv3FRyo2QApZ49NNDbwcR0ZndK0XFo15iH708H5Qja/8TuXCwnPWAcJ DQoNIDFyaxe26Rx3ZwUkRALa3iPcVjE0//TrQ4KnFf+lMBSrS33xDDBfevW9+Dk6IISmDH1R HFq2jpkN+FX/PE8eVhV68B2DsAPZ5rUwyCKUXPTJ/irrCCmAAb5Jpv11S7hUSpqtM/6oVESC 3z/7CzrVtRODzLtNgV4r5EI+wAv/3PgJLlMwgJM90Fb3CB2IgbxhjvmB1WNdvXACVydx55V7 LPPKodSTF29rlnQAf9HLgCphuuSrrPn5VQDaYZl4N/7zc2wcWM7BTQRVy5+RARAA59fefSDR 9nMGCb9LbMX+TFAoIQo/wgP5XPyzLYakO+94GrgfZjfhdaxPXMsl2+o8jhp/hlIzG56taNdt VZtPp3ih1AgbR8rHgXw1xwOpuAd5lE1qNd54ndHuADO9a9A0vPimIes78Hi1/yy+ZEEvRkHk /kDa6F3AtTc1m4rbbOk2fiKzzsE9YXweFjQvl9p+AMw6qd/iC4lUk9g0+FQXNdRs+o4o6Qvy iOQJfGQ4UcBuOy1IrkJrd8qq5jet1fcM2j4QvsW8CLDWZS1L7kZ5gT5EycMKxUWb8LuRjxzZ 3QY1aQH2kkzn6acigU3HLtgFyV1gBNV44ehjgvJpRY2cC8VhanTx0dZ9mj1YKIky5N+C0f21 zvntBqcxV0+3p8MrxRRcgEtDZNav+xAoT3G0W4SahAaUTWXpsZoOecwtxi74CyneQNPTDjNg azHmvpdBVEfj7k3p4dmJp5i0U66Onmf6mMFpArvBRSMOKU9DlAzMi4IvhiNWjKVaIE2Se9BY FdKVAJaZq85P2y20ZBd08ILnKcj7XKZkLU5FkoA0udEBvQ0f9QLNyyy3DZMCQWcwRuj1m73D sq8DEFBdZ5eEkj1dCyx+t/ga6x2rHyc8Sl86oK1tvAkwBNsfKou3v+jP/l14a7DGBvrmlYjO 59o3t6inu6H7pt7OL6u6BQj7DoMAEQEAAcLBfAQYAQgAJgIbDBYhBBvZyq1zXEw6Rg38yk3e EPcA/4NaBQJonNqrBQkmWAihAAoJEE3eEPcA/4NaKtMQALAJ8PzprBEXbXcEXwDKQu+P/vts IfUb1UNMfMV76BicGa5NCZnJNQASDP/+bFg6O3gx5NbhHHPeaWz/VxlOmYHokHodOvtL0WCC 8A5PEP8tOk6029Z+J+xUcMrJClNVFpzVvOpb1lCbhjwAV465Hy+NUSbbUiRxdzNQtLtgZzOV Zw7jxUCs4UUZLQTCuBpFgb15bBxYZ/BL9MbzxPxvfUQIPbnzQMcqtpUs21CMK2PdfCh5c4gS sDci6D5/ZIBw94UQWmGpM/O1ilGXde2ZzzGYl64glmccD8e87OnEgKnH3FbnJnT4iJchtSvx yJNi1+t0+qDti4m88+/9IuPqCKb6Stl+s2dnLtJNrjXBGJtsQG/sRpqsJz5x1/2nPJSRMsx9 5YfqbdrJSOFXDzZ8/r82HgQEtUvlSXNaXCa95ez0UkOG7+bDm2b3s0XahBQeLVCH0mw3RAQg r7xDAYKIrAwfHHmMTnBQDPJwVqxJjVNr7yBic4yfzVWGCGNE4DnOW0vcIeoyhy9vnIa3w1uZ 3iyY2Nsd7JxfKu1PRhCGwXzRw5TlfEsoRI7V9A8isUCoqE2Dzh3FvYHVeX4Us+bRL/oqareJ CIFqgYMyvHj7Q06kTKmauOe4Nf0l0qEkIuIzfoLJ3qr5UyXc2hLtWyT9Ir+lYlX9efqh7mOY qIws/H2t In-Reply-To: <20260506094504.2588857-5-dev.jain@arm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 5/6/26 11:44, 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. You should mention why the uffd_supports_wp_marker()+vma_is_anonymous() calls in zap_install_uffd_wp_if_needed can be dropped. > > No functional change is intended. > > Signed-off-by: Dev Jain > --- > include/linux/mm_inline.h | 34 +++++++++++++++++++++------------- > mm/memory.c | 20 +------------------- > mm/rmap.c | 2 +- > 3 files changed, 23 insertions(+), 33 deletions(-) > > diff --git a/include/linux/mm_inline.h b/include/linux/mm_inline.h > index a171070e15f05..6f7ecede2fb45 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 *ptep, pte_t pteval, unsigned long nr_ptes) If we conditionally do something, what about while at it shorten it to: cont_install_uffd_wp_ptes() Also, less churn in this patch if you don't change pte->ptep (because if you do, you should then also do pteval->pte :) ) So I'd just leave that as is in this patch. > { > bool arm_uffd_pte = false; > > @@ -588,7 +596,7 @@ pte_install_uffd_wp_if_needed(struct vm_area_struct *vma, unsigned long addr, > return false; > > /* The current status of the pte should be "cleared" before calling */ > - WARN_ON_ONCE(!pte_none(ptep_get(pte))); > + WARN_ON_ONCE(!pte_none(ptep_get(ptep))); > > /* > * NOTE: userfaultfd_wp_unpopulated() doesn't need this whole > @@ -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, ++ptep, addr += PAGE_SIZE) > + set_pte_at(vma->vm_mm, addr, ptep, make_pte_marker(PTE_MARKER_UFFD_WP)); > + > + return true; > } I wonder whether this growing function is really appropriate to be in the header file? Can we just move that whole thing into mm/memory.c? It's called on every try_to_unmap_one() invocation, but I doubt we care about a function call here. > > static inline bool vma_has_recency(const struct vm_area_struct *vma) > diff --git a/mm/memory.c b/mm/memory.c > index 0c9d9c2cbf0e0..f14311c4d2001 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -1610,29 +1610,11 @@ 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 bd4e3639e26ed..b17dce752a1ea 100644 > --- a/mm/rmap.c > +++ b/mm/rmap.c > @@ -2266,7 +2266,7 @@ 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); -- Cheers, David