From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (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 C6627446CF for ; Tue, 4 Jun 2024 08:12:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717488739; cv=none; b=vFzHNUHrYDbRk6GHO2TEif4oMlGX9nf+8ijn7Rl6uoDXUXtSMpLtT1uLS6QfinFhdCaE9SmdhaAonG+Sd5CLIDDK1I7qDLguUjEcEWck45ivFZOl1/o/v6GJeF96xVBNDdaMODZbGToTsrW2A40w1JE40MfwowXjRtS2WNG1lgg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717488739; c=relaxed/simple; bh=OjxiDW8aCLdBjhHwLO5juHvlhuDylHIig6Vdxijp6eA=; h=Message-ID:Date:MIME-Version:Subject:To:References:From: In-Reply-To:Content-Type; b=MF4oI1RxJKu+l1/mR6uQU2DmZM4UNNshZpOts82qub2Y902o8fnKtW/UwQJPjac53RHIyfo8YSbpafZ70Sah/m5LlOjIIiZOBS42SA9hayPBkx9URQfCeA+3gAsk/QuCg4858lRYyUdWWV1jTiE3LluirqxcU5FFagRrExhhfP4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=MSTXyiq7; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="MSTXyiq7" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1717488736; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:autocrypt:autocrypt; bh=NO46/e2k3bswdUgx3pOlFMftDVA9hEI7Aka+jetV9KM=; b=MSTXyiq7Pyv8TSnDAVSJznrLM3U08t3zgxP5728QwdodMpl49bj8xgc1z/abnQ/aBtgOQ4 0GM0Z3GXTRQIHnQUoDX3fd0n7eO4dS/SRbjY1oeR348LOyurl6zsQqRfXEooiB+fn24/wT bGuGy9qonNkdgFjD0VwxsfUcdcEwpM0= Received: from mail-wm1-f72.google.com (mail-wm1-f72.google.com [209.85.128.72]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-524-meFAFBkCO4WuLgSmGFgqPQ-1; Tue, 04 Jun 2024 04:12:15 -0400 X-MC-Unique: meFAFBkCO4WuLgSmGFgqPQ-1 Received: by mail-wm1-f72.google.com with SMTP id 5b1f17b1804b1-42120e123beso47774065e9.0 for ; Tue, 04 Jun 2024 01:12:15 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1717488734; x=1718093534; h=content-transfer-encoding:in-reply-to:organization:autocrypt :content-language:from:references:to:subject:user-agent:mime-version :date:message-id:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=NO46/e2k3bswdUgx3pOlFMftDVA9hEI7Aka+jetV9KM=; b=chEIXVf1FsSaVWP99Ci0dwOBJZmgrUEPbC8tL81WDPJPs9LLOMpZv4dzRRRQU+0O1L h9Xr3XoxMNTdDfcm0/bBe+8YJbDlE96wg3/7pZr85lSbsdBHOtjXiebPxAzQQC+6guNd RSdRsK25A64qK1zs8lCVi8+Oljg3nwScS7T7tkl0NgvK5ZRfsoMNBVQjJm4zp+iahUbn xyNOpLq4LhhzaRnz/xxvrFHgchd+qpli48Qm0W0fTXugpkOD6yW1MLgYklgOhCR70kqb KTN86tYkWy/tamzGaz5O2Sf1kQ1Sygrv8C0MCrhvzT91QJtNwR77H8zg69PI6Jynzp26 GgEA== X-Forwarded-Encrypted: i=1; AJvYcCW9ewI137ySVmqpqNzv1OW9WUgijp0T1B+4HjsdEhdy7i3h7JDGWP7ZP7ESncqqTv33RNT7m50TO38PGXTr1t8Abl7eHNVadMH6+RaL X-Gm-Message-State: AOJu0YyFPDdLvTSOha7tq1CbSAVYTB13qFTxtkCUzLtQ5TJ9RVte07GK /wjWzb/Rt3Qr8gmjdBotxPdyPz5vlFlnZdtJ3HVJnvE4Yitcf1QB1czpghYB8G9ZtOsHptL6K+g 7hhHzC4lNhEkbIxkeuNXJJHYwLm9kxKyapkZBu+rcy5Ue1If7ytUzVmjqheXlQQ== X-Received: by 2002:a05:600c:3c9f:b0:41c:2313:da8d with SMTP id 5b1f17b1804b1-4212e004b7amr121595655e9.0.1717488734093; Tue, 04 Jun 2024 01:12:14 -0700 (PDT) X-Google-Smtp-Source: AGHT+IHBkFzGm/IQ6fJfySmp0r/k+mQkzs3zDPPMDyKLC0UxmDPdH+oAHv5eyS+GEvBDE1JWUSSs2g== X-Received: by 2002:a05:600c:3c9f:b0:41c:2313:da8d with SMTP id 5b1f17b1804b1-4212e004b7amr121595465e9.0.1717488733728; Tue, 04 Jun 2024 01:12:13 -0700 (PDT) Received: from ?IPV6:2003:cb:c73a:3a00:a025:9b06:549e:c16b? (p200300cbc73a3a00a0259b06549ec16b.dip0.t-ipconnect.de. [2003:cb:c73a:3a00:a025:9b06:549e:c16b]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4212b838b55sm144195325e9.5.2024.06.04.01.12.12 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 04 Jun 2024 01:12:13 -0700 (PDT) Message-ID: <8d3a60d5-06c5-4df4-aeda-2fbec45a8ae0@redhat.com> Date: Tue, 4 Jun 2024 10:12:12 +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 02/10] mm/ksm: skip subpages of compound pages To: alexs@kernel.org, Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, izik.eidus@ravellosystems.com, willy@infradead.org, aarcange@redhat.com, chrisw@sous-sol.org, hughd@google.com References: <20240604042454.2012091-1-alexs@kernel.org> <20240604042454.2012091-3-alexs@kernel.org> From: David Hildenbrand Content-Language: en-US Autocrypt: addr=david@redhat.com; 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 B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzSREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwZgEEwEIAEICGwMGCwkIBwMCBhUIAgkKCwQW AgMBAh4BAheAAhkBFiEEG9nKrXNcTDpGDfzKTd4Q9wD/g1oFAl8Ox4kFCRKpKXgACgkQTd4Q 9wD/g1oHcA//a6Tj7SBNjFNM1iNhWUo1lxAja0lpSodSnB2g4FCZ4R61SBR4l/psBL73xktp rDHrx4aSpwkRP6Epu6mLvhlfjmkRG4OynJ5HG1gfv7RJJfnUdUM1z5kdS8JBrOhMJS2c/gPf wv1TGRq2XdMPnfY2o0CxRqpcLkx4vBODvJGl2mQyJF/gPepdDfcT8/PY9BJ7FL6Hrq1gnAo4 3Iv9qV0JiT2wmZciNyYQhmA1V6dyTRiQ4YAc31zOo2IM+xisPzeSHgw3ONY/XhYvfZ9r7W1l pNQdc2G+o4Di9NPFHQQhDw3YTRR1opJaTlRDzxYxzU6ZnUUBghxt9cwUWTpfCktkMZiPSDGd KgQBjnweV2jw9UOTxjb4LXqDjmSNkjDdQUOU69jGMUXgihvo4zhYcMX8F5gWdRtMR7DzW/YE BgVcyxNkMIXoY1aYj6npHYiNQesQlqjU6azjbH70/SXKM5tNRplgW8TNprMDuntdvV9wNkFs 9TyM02V5aWxFfI42+aivc4KEw69SE9KXwC7FSf5wXzuTot97N9Phj/Z3+jx443jo2NR34XgF 89cct7wJMjOF7bBefo0fPPZQuIma0Zym71cP61OP/i11ahNye6HGKfxGCOcs5wW9kRQEk8P9 M/k2wt3mt/fCQnuP/mWutNPt95w9wSsUyATLmtNrwccz63XOwU0EVcufkQEQAOfX3n0g0fZz Bgm/S2zF/kxQKCEKP8ID+Vz8sy2GpDvveBq4H2Y34XWsT1zLJdvqPI4af4ZSMxuerWjXbVWb T6d4odQIG0fKx4F8NccDqbgHeZRNajXeeJ3R7gAzvWvQNLz4piHrO/B4tf8svmRBL0ZB5P5A 2uhdwLU3NZuK22zpNn4is87BPWF8HhY0L5fafgDMOqnf4guJVJPYNPhUFzXUbPqOKOkL8ojk CXxkOFHAbjstSK5Ca3fKquY3rdX3DNo+EL7FvAiw1mUtS+5GeYE+RMnDCsVFm/C7kY8c2d0G NWkB9pJM5+mnIoFNxy7YBcldYATVeOHoY4LyaUWNnAvFYWp08dHWfZo9WCiJMuTfgtH9tc75 7QanMVdPt6fDK8UUXIBLQ2TWr/sQKE9xtFuEmoQGlE1l6bGaDnnMLcYu+Asp3kDT0w4zYGsx 5r6XQVRH4+5N6eHZiaeYtFOujp5n+pjBaQK7wUUjDilPQ5QMzIuCL4YjVoylWiBNknvQWBXS lQCWmavOT9sttGQXdPCC5ynI+1ymZC1ORZKANLnRAb0NH/UCzcsstw2TAkFnMEbo9Zu9w7Kv AxBQXWeXhJI9XQssfrf4Gusdqx8nPEpfOqCtbbwJMATbHyqLt7/oz/5deGuwxgb65pWIzufa N7eop7uh+6bezi+rugUI+w6DABEBAAHCwXwEGAEIACYCGwwWIQQb2cqtc1xMOkYN/MpN3hD3 AP+DWgUCXw7HsgUJEqkpoQAKCRBN3hD3AP+DWrrpD/4qS3dyVRxDcDHIlmguXjC1Q5tZTwNB boaBTPHSy/Nksu0eY7x6HfQJ3xajVH32Ms6t1trDQmPx2iP5+7iDsb7OKAb5eOS8h+BEBDeq 3ecsQDv0fFJOA9ag5O3LLNk+3x3q7e0uo06XMaY7UHS341ozXUUI7wC7iKfoUTv03iO9El5f XpNMx/YrIMduZ2+nd9Di7o5+KIwlb2mAB9sTNHdMrXesX8eBL6T9b+MZJk+mZuPxKNVfEQMQ a5SxUEADIPQTPNvBewdeI80yeOCrN+Zzwy/Mrx9EPeu59Y5vSJOx/z6OUImD/GhX7Xvkt3kq Er5KTrJz3++B6SH9pum9PuoE/k+nntJkNMmQpR4MCBaV/J9gIOPGodDKnjdng+mXliF3Ptu6 3oxc2RCyGzTlxyMwuc2U5Q7KtUNTdDe8T0uE+9b8BLMVQDDfJjqY0VVqSUwImzTDLX9S4g/8 kC4HRcclk8hpyhY2jKGluZO0awwTIMgVEzmTyBphDg/Gx7dZU1Xf8HFuE+UZ5UDHDTnwgv7E th6RC9+WrhDNspZ9fJjKWRbveQgUFCpe1sa77LAw+XFrKmBHXp9ZVIe90RMe2tRL06BGiRZr jPrnvUsUUsjRoRNJjKKA/REq+sAnhkNPPZ/NNMjaZ5b8Tovi8C0tmxiCHaQYqj7G2rgnT0kt WNyWQQ== Organization: Red Hat In-Reply-To: <20240604042454.2012091-3-alexs@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 04.06.24 06:24, alexs@kernel.org wrote: > From: "Alex Shi (tencent)" > > When a folio isn't fit for KSM, the subpages are unlikely to be good, > So let's skip the rest page checking to save some actions. > > Signed-off-by: Alex Shi (tencent) > --- > mm/ksm.c | 9 +++++++-- > 1 file changed, 7 insertions(+), 2 deletions(-) > > diff --git a/mm/ksm.c b/mm/ksm.c > index 97e5b41f8c4b..e2fdb9dd98e2 100644 > --- a/mm/ksm.c > +++ b/mm/ksm.c > @@ -2644,6 +2644,8 @@ static struct ksm_rmap_item *scan_get_next_rmap_item(struct page **page) > goto no_vmas; > > for_each_vma(vmi, vma) { > + int nr = 1; > + > if (!(vma->vm_flags & VM_MERGEABLE)) > continue; > if (ksm_scan.address < vma->vm_start) > @@ -2660,6 +2662,9 @@ static struct ksm_rmap_item *scan_get_next_rmap_item(struct page **page) > cond_resched(); > continue; > } > + > + VM_WARN_ON(PageTail(*page)); > + nr = compound_nr(*page); > if (is_zone_device_page(*page)) > goto next_page; > if (PageAnon(*page)) { > @@ -2672,7 +2677,7 @@ static struct ksm_rmap_item *scan_get_next_rmap_item(struct page **page) > if (should_skip_rmap_item(*page, rmap_item)) > goto next_page; > > - ksm_scan.address += PAGE_SIZE; > + ksm_scan.address += nr * PAGE_SIZE; > } else > put_page(*page); > mmap_read_unlock(mm); > @@ -2680,7 +2685,7 @@ static struct ksm_rmap_item *scan_get_next_rmap_item(struct page **page) > } > next_page: > put_page(*page); > - ksm_scan.address += PAGE_SIZE; > + ksm_scan.address += nr * PAGE_SIZE; > cond_resched(); > } > } You might be jumping over pages that don't belong to that folio. What you would actually want to do is somehow use folio_pte_batch() to really know the PTEs point at the same folio, so you can skip them. But that's not that easy when using follow_page() ... So I suggest dropping this change for now. -- Cheers, David / dhildenb