From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 BDE258632B for ; Wed, 8 Oct 2025 09:00:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759914021; cv=none; b=rDKg35suT3QtAZCqFZWU7gOSWkyhJ/6Yux1rjqeGm7CpnaHgXvlcTYyDpSFaHGTtbPH3122zkOl5m4nNpCa31ky06fK4RtOhg040UFNNPsUxjqk9l/JWgSJ9eBDOngFbNp21gOOR80uolYCicH2hlmjKUDF/YEF8whGYImwzhOg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759914021; c=relaxed/simple; bh=jxLMcX1Ra+xbVOI7n/I+MEAnub2QWF8EmVkfQLkDPR0=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=i7DeBHWUI9ImXFt4DJm3/BQ94CGSI2gpOUr+85YpT3Y5bKSRmmBDTPjTId3yZBrFSOMOahhydX1mbei8GjOQ6MoNJonzz2I/sYUx6seAXlGt/+VdQ5LUCWlCyZp6HTAJmmKqAx0B8aQzS37JylqoQAFBe0Z1Cjii/N4ZuoG1Rxc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine 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=BwWsZbb8; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine 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="BwWsZbb8" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1759914018; h=from:from: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:content-transfer-encoding: in-reply-to:in-reply-to:references:references:autocrypt:autocrypt; bh=bNb165tATUdzEB7JEIVixwqTS/ioT+20Th0ZR/SpPvM=; b=BwWsZbb8AZFk0ZbUAOC+mh3AlcEfGreD3MYi933HAMa5xNpRRw1V02m1K0SpwZcWbmRgcT OkiQSzsWlDMlvDYiATzH3fEChDwXYLI15pzzG5enofsYQ77pqkypVEBPfcwUEGBpd9kpam f9D/KTIv7jo/4qAZ7sIdTmO+fMKemYY= 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-549-6DhFLUfJNEyYm-iFD0XgMg-1; Wed, 08 Oct 2025 05:00:17 -0400 X-MC-Unique: 6DhFLUfJNEyYm-iFD0XgMg-1 X-Mimecast-MFC-AGG-ID: 6DhFLUfJNEyYm-iFD0XgMg_1759914016 Received: by mail-wm1-f72.google.com with SMTP id 5b1f17b1804b1-46e3af78819so32292415e9.1 for ; Wed, 08 Oct 2025 02:00:17 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1759914016; x=1760518816; h=content-transfer-encoding:in-reply-to:autocrypt:content-language :from:references:cc:to:subject:user-agent:mime-version:date :message-id:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=bNb165tATUdzEB7JEIVixwqTS/ioT+20Th0ZR/SpPvM=; b=J71UwwC02K53G2rphX8WDS+d8gTP7ZzlYqxyFs7tuzKsUe2WexxcCnpPIlY2PPPSx2 b2s2x5YQFdoVBrR7gCbYeCl62xuYvZbuy3I2lwW6Bg79uz909bU4QaKX/00pbIM/l5bn XhwsYjWYpORiVZr7FSiG3Tl0i3hBeTNHTqAreaO9O9BhfaUDQ9q1iaajf/NjVjqUtlf1 8MB8XsyBl7Vy8IQIBXllIfuCJtbznAFDVwva2EJZmTdv0eS3eue7lUJrfSEOkP9yn2lr KqUjZ/5LWoiKdjoDYJEFF2rtAt10KUgJYMDOnreZEeMpoFSJ305yJsYnoGJwHHPF/SdR Y/sQ== X-Forwarded-Encrypted: i=1; AJvYcCXduika11lXwKDyLdCaoBordFqp0iVtGCCQVjcOwmOaG+IGuU+oGYSE3RLd5OqTq8JDHj2C2YY5pi4Xd48=@vger.kernel.org X-Gm-Message-State: AOJu0Yz+6/0aLWigmfNsRxGuYLyjT2cs2Vm7tmktiYzSgFaTHldmZvEX VErDAl8cH8eXfAsfoq2LJNgTOqzD+xlnQ5ohPC0wEd52ucIWyzRAQ/4C3XkDBcrLgSan5AwIPt5 zXipO+PwEVHnRtgAdCL0qNu/t7pWRO5kYghNgTZ0QTvN+yydMXiOvesTIAWYPYoIKcg== X-Gm-Gg: ASbGnctnLOCVDZ/0olv+XWpqbtFfx+/vvfmUT4CBrGZxRYpNbpd4qvPOAZGbC9s0SVq eJAiC7T30LBPlF5HnIeyp1IVSZYhzWqkfT2vkT6btXzD6rb7uEa7PB0crmnP1+PaNOuf5W88Mmx t1kWSwTzEwCN9UR2Igfwu7Dw5RXpH6S5q9ieurXxCznVIVqIij3VzE8dgwmelXeEbBrTUOaryrj qym+s1cZ8gEQCXGzFcdDN/52/0OK+1OHYiEvW7w191T9aHpH/abC3SRvsMLIk+0g71z1WQZlJJq hp4iW3KkEF6qZQ89oqDtTwlpy+8MrONarbnjFQce+PhcJJdaYL7WqPpEYM6gs/yWeXc19TrkLY0 fxYF8v9W2 X-Received: by 2002:a05:600c:474d:b0:459:d451:3364 with SMTP id 5b1f17b1804b1-46fa9af81d5mr18773305e9.24.1759914015782; Wed, 08 Oct 2025 02:00:15 -0700 (PDT) X-Google-Smtp-Source: AGHT+IHj5sfOcndDzAGeB9+llIRFsdMQVfmW8QZxnb1MAChDDnGTI6DfgD3G8B8EpgzHWOlxYFknRA== X-Received: by 2002:a05:600c:474d:b0:459:d451:3364 with SMTP id 5b1f17b1804b1-46fa9af81d5mr18773025e9.24.1759914015233; Wed, 08 Oct 2025 02:00:15 -0700 (PDT) Received: from [192.168.3.141] (tmo-083-110.customers.d1-online.com. [80.187.83.110]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-46fa9bf8295sm28492525e9.3.2025.10.08.02.00.11 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 08 Oct 2025 02:00:14 -0700 (PDT) Message-ID: <1c2fae79-69ad-45c2-8da7-31b3cd6dcda0@redhat.com> Date: Wed, 8 Oct 2025 11:00:09 +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 mm-new v2 1/1] mm/khugepaged: abort collapse scan on non-swap entries To: Lance Yang , Wei Yang Cc: akpm@linux-foundation.org, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, baohua@kernel.org, baolin.wang@linux.alibaba.com, dev.jain@arm.com, hughd@google.com, ioworker0@gmail.com, kirill@shutemov.name, linux-kernel@vger.kernel.org, linux-mm@kvack.org, mpenttil@redhat.com, npache@redhat.com, ryan.roberts@arm.com, ziy@nvidia.com References: <20251001032251.85888-1-lance.yang@linux.dev> <20251001085425.5iq2mgfom6sqkbbx@master> <1d09acbf-ccc9-4f06-9392-669c98e34661@linux.dev> <20251005010511.ysek2nqojebqngf3@master> <31c3f774-edb7-420a-a6a8-3e21f2abd776@linux.dev> <09eaca7b-9988-41c7-8d6e-4802055b3f1e@redhat.com> <29742109-13c2-4fa6-a3a1-d12b14641404@linux.dev> 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 ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwZoEEwEIAEQCGwMCF4ACGQEFCwkIBwICIgIG FQoJCAsCBBYCAwECHgcWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaJzangUJJlgIpAAKCRBN 3hD3AP+DWhAxD/9wcL0A+2rtaAmutaKTfxhTP0b4AAp1r/eLxjrbfbCCmh4pqzBhmSX/4z11 opn2KqcOsueRF1t2ENLOWzQu3Roiny2HOU7DajqB4dm1BVMaXQya5ae2ghzlJN9SIoopTWlR 0Af3hPj5E2PYvQhlcqeoehKlBo9rROJv/rjmr2x0yOM8qeTroH/ZzNlCtJ56AsE6Tvl+r7cW 3x7/Jq5WvWeudKrhFh7/yQ7eRvHCjd9bBrZTlgAfiHmX9AnCCPRPpNGNedV9Yty2Jnxhfmbv Pw37LA/jef8zlCDyUh2KCU1xVEOWqg15o1RtTyGV1nXV2O/mfuQJud5vIgzBvHhypc3p6VZJ lEf8YmT+Ol5P7SfCs5/uGdWUYQEMqOlg6w9R4Pe8d+mk8KGvfE9/zTwGg0nRgKqlQXrWRERv cuEwQbridlPAoQHrFWtwpgYMXx2TaZ3sihcIPo9uU5eBs0rf4mOERY75SK+Ekayv2ucTfjxr Kf014py2aoRJHuvy85ee/zIyLmve5hngZTTe3Wg3TInT9UTFzTPhItam6dZ1xqdTGHZYGU0O otRHcwLGt470grdiob6PfVTXoHlBvkWRadMhSuG4RORCDpq89vu5QralFNIf3EysNohoFy2A LYg2/D53xbU/aa4DDzBb5b1Rkg/udO1gZocVQWrDh6I2K3+cCs7BTQRVy5+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: <29742109-13c2-4fa6-a3a1-d12b14641404@linux.dev> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit > Second, as Wei pointed out[3], we may have a chance to get a non-swap > entry, since we will drop and re-acquire the mmap lock before > __collapse_huge_page_swapin(). To handle this, we also add a > non_swap_entry() check there. > > Note that we can unlock later what we really need, and not account it > towards max_swap_ptes. > > [1] > https://lore.kernel.org/linux-mm/09eaca7b-9988-41c7-8d6e-4802055b3f1e@redhat.com > [2] > https://lore.kernel.org/linux-mm/7df49fe7-c6b7-426a-8680-dcd55219c8bd@lucifer.local > [3] https://lore.kernel.org/linux-mm/20251005010511.ysek2nqojebqngf3@master > ``` > I replied to the new version. > I also think it makes sense to fold the change that adds the > non_swap_entry() check in __collapse_huge_page_swapin() into > this patch, rather than creating a new patch just for that :) > > Hmmm... one thing I'm not sure about: regarding the uffd-wp > race you mentioned, is the pte_swp_uffd_wp() check needed > after non_swap_entry()? It seems like it might not be ... > If we check non_swap_entry(), there is no need to check for other markers, agreed. -- Cheers David / dhildenb