From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 66DCCF94CB4 for ; Tue, 21 Apr 2026 22:01:59 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id D440F6B00A3; Tue, 21 Apr 2026 18:01:58 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id D1A9F6B0005; Tue, 21 Apr 2026 18:01:58 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C0A506B00A5; Tue, 21 Apr 2026 18:01:58 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id AF9846B00A3 for ; Tue, 21 Apr 2026 18:01:58 -0400 (EDT) Received: from smtpin20.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id 80BD2160AF4 for ; Tue, 21 Apr 2026 22:01:58 +0000 (UTC) X-FDA: 84683936316.20.07C8664 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by imf27.hostedemail.com (Postfix) with ESMTP id 408A640006 for ; Tue, 21 Apr 2026 22:01:56 +0000 (UTC) Authentication-Results: imf27.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=Jz9PhPsM; spf=pass (imf27.hostedemail.com: domain of mst@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=mst@redhat.com; dmarc=pass (policy=quarantine) header.from=redhat.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1776808916; h=from:from:sender: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: in-reply-to:in-reply-to:references:references:dkim-signature; bh=iXNCfNPQyocyWkSCOxjnq/WqPhuX3fxPK4FCFhhbcx8=; b=pg1nOPg5nWElXetbTVWk/LgFnEMQmRL6dh8Qd4PcBEjy7jaeXMn0k2TkVhDSkUFwCH1Icj jMj7qOTjwtot/gS3M6Yk6kLNHdw6C2ykCwriFpkSavCW9AxsTy1j9uf9y/AmC2YkmJ6WNZ 1BrmSnDOuZx59MRjX8fHe8Uj0Mnh/2w= ARC-Authentication-Results: i=1; imf27.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=Jz9PhPsM; spf=pass (imf27.hostedemail.com: domain of mst@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=mst@redhat.com; dmarc=pass (policy=quarantine) header.from=redhat.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1776808916; a=rsa-sha256; cv=none; b=sPHBT45IDJ2EHlfl5+6rRswZUYOlYIPjTSDQU0kc4FGvvcUBbCUzT29RvF8iz4GZWDgmrr ZvSDXv+5dmKL3Qk4FNhfYZtyt3PvRMisIHSmkAgji3EjGMl/LPLwFHj5pZ2LUA20VwdWYl v4yvM9hBEXV/SGmV3KzBDO58zq+bKPs= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1776808915; 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=iXNCfNPQyocyWkSCOxjnq/WqPhuX3fxPK4FCFhhbcx8=; b=Jz9PhPsM9gOgMvBHlFx4KSWEUbp13QBKx7u5ZOp7hoFSh+cEHhJTwXsQ600XsQOoMMvfKb AgW22NsqkwU4sgMEXqCxeFG4IleoKbZWpZma7Skf16MqHd6NBU5kZ4MjxTdQsTIw+5wCp2 g4m4nG3oHttL34Q3EVXtaIkuJttQZ64= Received: from mail-wr1-f70.google.com (mail-wr1-f70.google.com [209.85.221.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-411-PGV6V4xNNNest68ImHJo9w-1; Tue, 21 Apr 2026 18:01:51 -0400 X-MC-Unique: PGV6V4xNNNest68ImHJo9w-1 X-Mimecast-MFC-AGG-ID: PGV6V4xNNNest68ImHJo9w_1776808911 Received: by mail-wr1-f70.google.com with SMTP id ffacd0b85a97d-43d1dea12aaso3928505f8f.1 for ; Tue, 21 Apr 2026 15:01:51 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1776808911; x=1777413711; 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=iXNCfNPQyocyWkSCOxjnq/WqPhuX3fxPK4FCFhhbcx8=; b=cV84NK3UDTP0wXa4XZH/Tt1g3k1vU+i+Xn3JdqsD/fTxB6ztxKCLLuNP+gqhDbaOPf ykg+7OoN8BpfRJTJFC4SRBiYrpewwBGxZo+WNFYxVK0p5XPSY6ZwyG2DINta8A2Tk85m crcxv2Qerw0y0YyS0e2sWxoYDteJ4sn3931QRYzukBFWIOOrMFMbmbrJ729AHUJllGr9 Es2AQnZu50nOXt5gFoKabj59INm0UuQBlqoTRIPMGfn4NJLVcZYM0PKSjPgYAFWYq0e2 eSIeMXqpziz5MoW7p1QvQiTunCp+v+fYPgLvVQuRIm1IIxIC27I9QCqvQftTGKOxGGSw Ybgg== X-Forwarded-Encrypted: i=1; AFNElJ9AohcZK2Wx4bwLYETUI2E+sqgU8EfR49rbvQFOLjOldPLLEO+BxJ/jsY4tfvYXOMIIVt4fSm3/Aw==@kvack.org X-Gm-Message-State: AOJu0YzjNEmouK90wfKRCTygtgEQej4DlABO1ejgZVlx0ifrV4pB8WAN 8yfPoUH+IdaH2fOJNmiQGnFFj4ohoCRyZQCYqSm3RgO6eXr4Lim9kPSpUFj11R8x62ZQVtHHYfJ 85OZ8bO049G5HquuBSAZ8ST3q71GE2XCczgUeGUe5Ad/VlbZPJbwW X-Gm-Gg: AeBDievnYL+hJ5yS0BR7QazxGoXU2UV3Od9TwdJt14XW2maCLW622DWLKKpmCANLhvH SPY2A3uLz1K7XVgPa5DwI3t+za4TbPDpW2mP6Ea0V68SgJUNDuHTkrXDbvCVevbm59VAUijJKoO wWtsPSvaIyebMAWMrlpr5QCESCZOp4d3HQValkvbnxg0MFwz3sgQKKps+4RRKzFnRcZuXy29nqs waZ1we4KwqrYcrFYHzfdwjF54gIEreT3HRKZj6NWQXIrTwz6y+pQUPRl2x8LEdbTFo4tfLeBmrN UvozibMjnmy7ayZJKu1B+f+a3488jY7fRdL458jdwU8sJ/94bnUs0OA/Rsn+1lR4+XRJ1SD8UTe 5EDL8XlLbs8Cxlv0W5ceX6erUN1I5WZkHUTdoz8yJnL/zyn/TJScIsw== X-Received: by 2002:a05:6000:2481:b0:43d:77a8:3bb6 with SMTP id ffacd0b85a97d-43fe3e239d9mr31452780f8f.47.1776808910671; Tue, 21 Apr 2026 15:01:50 -0700 (PDT) X-Received: by 2002:a05:6000:2481:b0:43d:77a8:3bb6 with SMTP id ffacd0b85a97d-43fe3e239d9mr31452682f8f.47.1776808909583; Tue, 21 Apr 2026 15:01:49 -0700 (PDT) Received: from redhat.com (IGLD-80-230-25-21.inter.net.il. [80.230.25.21]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-43fe4cc375dsm36898455f8f.14.2026.04.21.15.01.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 21 Apr 2026 15:01:48 -0700 (PDT) Date: Tue, 21 Apr 2026 18:01:46 -0400 From: "Michael S. Tsirkin" To: linux-kernel@vger.kernel.org Cc: Andrew Morton , David Hildenbrand , Vlastimil Babka , Brendan Jackman , Michal Hocko , Suren Baghdasaryan , Jason Wang , Andrea Arcangeli , Gregory Price , linux-mm@kvack.org, virtualization@lists.linux.dev, Johannes Weiner , Zi Yan Subject: [PATCH RFC v3 11/19] mm: page_alloc: propagate PageReported flag across buddy splits Message-ID: <7d1337e364980896be012ab34fd26bb3bf82c7af.1776808210.git.mst@redhat.com> References: MIME-Version: 1.0 In-Reply-To: X-Mailer: git-send-email 2.27.0.106.g8ac3dc51b1 X-Mutt-Fcc: =sent X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: IuvVS2SXFh2ohZAZr0Mfd6dfdVZTzJgCayB4BsIl6uA_1776808911 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 408A640006 X-Stat-Signature: 6p7qor8f4m8ojn9e36asgu6kzqsrhws5 X-Rspam-User: X-HE-Tag: 1776808916-582144 X-HE-Meta: U2FsdGVkX19CiR1ufEF8QJiD04JLuqDBQQ88cFyaxirqn2/GtXpB4dC9RroX+ek1kKZ1cntMhQEYuSt6kV9FsumPilr6aQIPMHUwduBYZ0Yr9vNSPTNJ9TO/EVHW/UGC39uYZN/oFbPgIJVdQaX8Rur1PQe/s3nUN5rsjTyZsIEKFgbagmts18tAYa1BP49ydXFoABfZnscScjKddPEbYEMVzCkipxLYfvOUM4Hlys/jzaPygNQJRQBROL00jkYDUZDyPLIgj8GBX9G0oQTAhw+B0p2Li/eRFYpzfL8JYP2Q1txYBRrhBFyi9VTLJvUqmTRCD7DwIzQFsRRvZquDogl5uaLdkNe4Wm49CMz0zv+rKVJaVT4r7j/tNIIichEWLCqOrS898YvBSvAkJzxPnz0MGQqblouhMC4Rn3lJTv3bF96pLM9zt1S7H/pHeJ35igIguEbel+R+GWldwUoonV6Xvsx2YbRSWTsC4errBrMLo0iiVj1pQJ8CZhY9PdlE22GAHt77VN87JpBTjyMeBnZ9Cl4uPQA0aq2SWRl13fBOla4t9JB/P7ije8VLXPMy4VN18mV2loiGMqAjeH4caUC+Av9xlYhl1g9nUDxsZp1Vs2YztXXpFpILeNkTmldl/pitvOWTL0TKBT42mlfx0aVSQ6i8rAXi7ewhzGiZFhs1SNa4PJCF/aOzCLUvAsyAL9/eIPtZcUQqTlfda9J+6Ugp6z1mMEEjlm4xlJzAUw2jNqzz+IqyTtgpkeqVVnDrbLTmUeAxjuKGVjTjVAlX/3iv22etE6Z+MlsG/z08cVLIaMbHKe+wjeelpUegxsL6lCys+qZ7w4NNF8TnABduhSaKMevSaOWKYsAzV+5Tlp6L+BBhSZjgnDd12zazKHwZg9wGjSOVXDBWkd9zOyN7cqTCiUJavnNuHVxJe+VwpFK5hi7x7BzwCFRfphpu5COnOt83mszY1PMtaqkatco F+XN8IZI c+erfpIWAjdE8jezjYyh41Hdn+AxKKwtwzWbDDhOcANuq+FjwnvqcNmh/e4fG2h6ElHk2xIQotN008Pj9QgGG7llXxXN7Va82R4lNHuowxhY3/HBDcgzl2+c93HR2YCv9jpIbS+UTd8stQBuELbbFGsUQWjGPKRtBrRteuC+/PCnA0KaRxQ3Mgfk2TbHSQF6vXMEsTk+Cjmd3cZt5TwLMgt6OzeSxvvAGb8TkbJrI9Dlx88A5ynh4NZIQGXSZwo2cv3V0EelehRnMvOtE2e8VOG2wM9IAeG5eJsO2rNjxTKX0XS+cWENt7i94aBdgA5+oMEuHWrgqySmgVuOqLfdoK9kB6Sg9obasywtkm37Mi4wf1htDdKxVZwNjWB6YVAZo3ZLN7NMXsUNrmPm9w1+AkGhIhRrhCFSjZPrA Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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. Propagate the PageReported flag to sub-pages during expand() so that they are recognized as already-reported. Signed-off-by: Michael S. Tsirkin Assisted-by: Claude:claude-opus-4-6 --- mm/page_alloc.c | 17 ++++++++++++++--- 1 file changed, 14 insertions(+), 3 deletions(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index db2192ffc27c..211e9e32b91d 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1730,7 +1730,7 @@ struct page *__pageblock_pfn_to_page(unsigned long start_pfn, * -- nyc */ static inline unsigned int expand(struct zone *zone, struct page *page, int low, - int high, int migratetype) + int high, int migratetype, bool reported) { unsigned int size = 1 << high; unsigned int nr_added = 0; @@ -1752,6 +1752,15 @@ static inline unsigned int expand(struct zone *zone, struct page *page, int low, __add_to_free_list(&page[size], zone, high, migratetype, false); set_buddy_order(&page[size], high); nr_added += size; + + /* + * The parent page has been reported to the host. The + * sub-pages are part of the same reported block, so mark + * them reported too. This avoids re-reporting pages that + * the host already knows about. + */ + if (reported) + __SetPageReported(&page[size]); } return nr_added; @@ -1762,9 +1771,10 @@ static __always_inline void page_del_and_expand(struct zone *zone, int high, int migratetype) { int nr_pages = 1 << high; + bool was_reported = page_reported(page); __del_page_from_free_list(page, zone, high, migratetype); - nr_pages -= expand(zone, page, low, high, migratetype); + nr_pages -= expand(zone, page, low, high, migratetype, was_reported); account_freepages(zone, -nr_pages, migratetype); } @@ -2334,7 +2344,8 @@ try_to_claim_block(struct zone *zone, struct page *page, del_page_from_free_list(page, zone, current_order, block_type); change_pageblock_range(page, current_order, start_type); - nr_added = expand(zone, page, order, current_order, start_type); + nr_added = expand(zone, page, order, current_order, start_type, + false); account_freepages(zone, nr_added, start_type); return page; } -- MST