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 A51A23655E9 for ; Tue, 12 May 2026 15:46:58 +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=1778600820; cv=none; b=VqIw34snKxLqipYW33cwiutB3Ro5RwThriAqSnxBDrWIpUztQhQBXWf8lVoZ14ir8OqyNY3vz/OEcPgzObZtGwEMThHA4p9Au9eLYAOkb1gGsCd6LmwQNL1eUBWek3gLD6KaNosJW4WvWovTst0bUNvCu8K5TlxbbJxvLoQL+P4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778600820; c=relaxed/simple; bh=85MVWieRjIr9XeWPe00hVIwtpgpudGUooADPlWLQ24Q=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: In-Reply-To:Content-Type:Content-Disposition; b=XL0RC7rjOeKJS3vyzeMaxfDyDBvQ+Z5hK6i8KThsV8GdeA3Pi7gOZjm6elFrNlzSPqQJTC6jFnIdxMxJOJbcY3XQUhfsGHtkxC5E2rBZhK7yRrnJ3q7f3bEfefsUvaODtMjlbttbysIXyQh8Y4IjBY7s1Vy03IMXpmxozL7raJk= 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=iYwkEbu8; 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="iYwkEbu8" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1778600817; 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: in-reply-to:in-reply-to:references:references; bh=bz4SWbhgAVm51cXT8NXKcag9UUTqJROZ/+vdmfbYWAM=; b=iYwkEbu8ofxRHC3kDpGFd3nrWbs9OCNzXaErMkIJrsA6d5piSSO8hqsWfpA+f4nXmbIpwL CTeg/Jct1lS0maqjko7e5tIbHcSTP3sFGQVJusOBLTWkHHon1t8k47TGWftRguF+KJO1x/ jDsqHjGuyrHas7ICMmWAPqFEt+4q3C0= Received: from mail-wr1-f69.google.com (mail-wr1-f69.google.com [209.85.221.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-41-C3Fn9dnJMm-k-lXLmlZ4Cw-1; Tue, 12 May 2026 11:46:54 -0400 X-MC-Unique: C3Fn9dnJMm-k-lXLmlZ4Cw-1 X-Mimecast-MFC-AGG-ID: C3Fn9dnJMm-k-lXLmlZ4Cw_1778600813 Received: by mail-wr1-f69.google.com with SMTP id ffacd0b85a97d-4411a36715dso4134051f8f.2 for ; Tue, 12 May 2026 08:46:54 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1778600813; x=1779205613; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-gg:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=bz4SWbhgAVm51cXT8NXKcag9UUTqJROZ/+vdmfbYWAM=; b=SdUGDHFUpP6w9gWUVW5azSvesLX0bCW7diJOz/ZzGb5b9S350/cZgjp7ecnyVTt6sf gGJ6PG1WX4qZU2BOCWk/zRGwmYMauwtLimViB8q/Rx18IpZc1QFIy9PQS+WS6UNB7dth jaTveOb5eRtzJB4MEPFHa4G7WF3/ugzDMSnf2gFM/Mv2SCNkYL9bOoZXuoQD2ynUvHi+ F+4FzxOBeMXCUj4LSghYxqvpW8ix9x58idImsIeHjnHQ670ZtWoWS6WRKgBPwE/nRTVj BfKAKD/X9kU0Yg/QPKcm69mMnFETFOVIZNM60A4PNCUa6kTw8fm5jn96ZOXPfkTYtZRd e3Ag== X-Forwarded-Encrypted: i=1; AFNElJ8QcGxC+MUxJ45LJdtG0J9hIYKgcT4q56VuKE6BHIDNa55o7nZ5q6p+MKMLOua9nSSrrR8GLryXBKQYOD22qA==@lists.linux.dev X-Gm-Message-State: AOJu0YwRNrcvi3yGF6StmMkdhdNCV4RRKIW9LNptaMmzymlsWQApX4v6 04LOfksweDPyhYuX7125cnUdGhY0ht7lxdNREysOoZb09Tr1pGE1bBhuW3XiYvcanPB/Cc4tuiC cIqfAjP1itQ8Gj/2BodhZu4sn+m1e2BpjCHT+Z2bbh2Dvt7l5R53G0WG9tiLNwqDwF+Wd X-Gm-Gg: Acq92OGSKcheEj9NXls63BU0kdZoMYTajI25rl+ZmGDEiE0mkA7X3wBfZL1Thr6qWOc 2yErc+mh7Axy+871jY01ziY71j5QeCeC6ND9nXRaiy8trwZYje6/MXKQhExQHEHN/Wus4CWHbSq BRgMEp6kyhTpXP9DZfLaywNI8T0PztXe6OejZpV4TsJlX1AXuG296mJrhPGPbl89PLO09jY/N+5 gx00DsobLiWqG6ITRG/Y10Z+a02+mrFpg0tz0URxHTGojOp1vLPayH1G40jSf1JmvD8tQK+Yoo9 nfhhmYKHrubCQvmvk0Z7zDIA1RTVPoHXmsSHY+RrOFBwsQYW/rsM75fPZV8vC6gDQd3zSutP2MY F11/ge0UEwe4N9yTLdEX1oRUbZ+xYwCOG0o3dHorA X-Received: by 2002:a05:600c:198a:b0:489:1c1f:35f9 with SMTP id 5b1f17b1804b1-48e8fe50bbbmr58590555e9.9.1778600812916; Tue, 12 May 2026 08:46:52 -0700 (PDT) X-Received: by 2002:a05:600c:198a:b0:489:1c1f:35f9 with SMTP id 5b1f17b1804b1-48e8fe50bbbmr58589455e9.9.1778600812271; Tue, 12 May 2026 08:46:52 -0700 (PDT) Received: from redhat.com (IGLD-80-230-48-7.inter.net.il. [80.230.48.7]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-454913049ecsm32654384f8f.19.2026.05.12.08.46.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 12 May 2026 08:46:51 -0700 (PDT) Date: Tue, 12 May 2026 11:46:46 -0400 From: "Michael S. Tsirkin" To: Gregory Price Cc: linux-kernel@vger.kernel.org, "David Hildenbrand (Arm)" , Jason Wang , Xuan Zhuo , Eugenio =?iso-8859-1?Q?P=E9rez?= , Muchun Song , Oscar Salvador , Andrew Morton , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Brendan Jackman , Johannes Weiner , Zi Yan , Baolin Wang , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Hugh Dickins , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Ying Huang , Alistair Popple , Christoph Lameter , David Rientjes , Roman Gushchin , Harry Yoo , Axel Rasmussen , Yuanchu Xie , Wei Xu , Chris Li , Kairui Song , Kemeng Shi , Nhat Pham , Baoquan He , virtualization@lists.linux.dev, linux-mm@kvack.org, Andrea Arcangeli Subject: Re: [PATCH resend v6 17/30] mm: page_alloc: propagate PageReported flag across buddy splits Message-ID: <20260512114352-mutt-send-email-mst@kernel.org> References: <6d98a35c94fa44b550afa66923c620511e2826f0.1778489843.git.mst@redhat.com> Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: 2izB9NthwtQhbtUBvjiLsbnZxMxrf7F27PTrQW3WCKw_1778600813 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Tue, May 12, 2026 at 11:40:08AM -0400, Gregory Price wrote: > On Mon, May 11, 2026 at 05:03:19AM -0400, Michael S. Tsirkin wrote: > > When a reported free page is split via expand() to satisfy a > > smaller allocation, the sub-pages placed back on the free lists > > lose the PageReported flag. This means they will be unnecessarily > > re-reported to the hypervisor in the next reporting cycle, wasting > > work. > > > > Is this issue generated by the changes in the overall patch set, or an > issue present regardless of the proposed zeroing avoidance feature? > > If the former, then maybe just submit as a standalone patch, seems like > a useful improvement regardless. The former but then the only issue is more reporting, and I couldn't find a benchmark that would quantify the performance difference. So the value of pushing a fix by itself is pretty low. > If fundamentally tied to the zeroing-avoidance feature, then nudging > this to the front or end of the series (depending on conflicts) would > help focus the review of the core new feature. > > ~Gregory I can nudge it forward sure. -- MST