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 CFCEFC5AD5A for ; Sat, 15 Aug 2026 14:44:33 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id A27C66B07D1; Sat, 15 Aug 2026 10:44:32 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 9FF526B07D3; Sat, 15 Aug 2026 10:44:32 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 93BFF6B07D4; Sat, 15 Aug 2026 10:44:32 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 5C2386B07D1 for ; Sat, 15 Aug 2026 10:44:32 -0400 (EDT) Received: from smtpin07.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay09.hostedemail.com (Postfix) with ESMTP id A279A80371 for ; Sat, 15 Aug 2026 14:44:31 +0000 (UTC) X-FDA: 85103774742.07.8E26FEE Received: from mta0.migadu.com (out-239.mta0.migadu.com [91.218.175.239]) by imf27.hostedemail.com (Postfix) with ESMTP id 9A36E40002 for ; Sat, 15 Aug 2026 14:44:29 +0000 (UTC) Authentication-Results: imf27.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=UFQWiPiY; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf27.hostedemail.com: domain of brendan.jackman@linux.dev designates 91.218.175.239 as permitted sender) smtp.mailfrom=brendan.jackman@linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1786805069; 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:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=0FyocDWbiKEhWozB7O216bJDmqB/VWihVNpwHu3R+Vo=; b=JJ/0BmsAye7VfXjAiniW1/zQiZxfAfdZwP0IT/fNRnmGpKUHM8aC9zWcXKzihlqvcmm2UF MY6fhvFkHmfWetqgi3kwboijFrG57OrOWaBll3kLZ683hZnLH5Cukl5C5nAN4vzDJR7mbf 79fBXJgVWxbp2FY3fkWzAZx+Zd36bf8= ARC-Authentication-Results: i=1; imf27.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=UFQWiPiY; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf27.hostedemail.com: domain of brendan.jackman@linux.dev designates 91.218.175.239 as permitted sender) smtp.mailfrom=brendan.jackman@linux.dev ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1786805069; b=itt4YEQ0cSlWXeGl9ay3X6GVd8rvYPpKHLFjq1hldmFoBo4wDHpSvKn+SVm0GtIFx0HUOq V8ZhJTsETlbL/KOL76DuTocK7wS/j0ncauluAk/wH3NnCLvtU/V1QJ2NZY+5hP2EPOGYY3 PWAk/nQWcxAIA460R0x557SoJaW3rvY= X-Envelope-To: linux-mm@kvack.org DKIM-Signature: a=rsa-sha256; bh=ihwcnUGvpCpT1va2cNKOoueJ4crpL+N4d9Fdxf7d0bQ=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1786805068; v=1; x=1787409868; b=UFQWiPiYnWXg9RLDyWIyRVKSpNYTEV+yAy8qHmeQci53th70XiSGBBi44or+5TsY9ixRSFAJ TJc91WE+mEbRtA5oWBtLbmlS2sRrxL+5/wBd/P1KVaIAVNosQIajD38dBs8JtoIIEQr0wE7mH10 cjK/8Bvz1WSicLVyPg9VX2yo= X-Envelope-To: linux-mm@kvack.org Received: from localhost (77.97.51.77) by smtp.migadu.com with ESMTPS id 93f03fcd28b6c3a6; Sat, 15 Aug 2026 14:44:27 +0000 X-Migadu-Flow: FLOW_OUT Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Sat, 15 Aug 2026 15:44:26 +0100 Message-Id: Cc: , , , "Sumit Garg" , "Will Deacon" , , , "Itazuri, Takahiro" , "Andy Lutomirski" , "David Kaplan" , "Thomas Gleixner" , "Yosry Ahmed" , "Patrick Bellasi" , "Reiji Watanabe" , "Sean Christopherson" Subject: Re: [PATCH v3 24/26] mm/page_alloc: always direct compact for unmapped allocs From: "Brendan Jackman" To: "Vlastimil Babka (SUSE)" , "Borislav Petkov" , "Dave Hansen" , "Peter Zijlstra" , "Andrew Morton" , "David Hildenbrand" , "Mike Rapoport" , "Wei Xu" , "Johannes Weiner" , "Zi Yan" , "Lorenzo Stoakes" X-Mailer: aerc 0.21.0 References: <20260726-page_alloc-unmapped-v3-0-6f5729aa9832@google.com> <20260726-page_alloc-unmapped-v3-24-6f5729aa9832@google.com> <60bd3790-f350-44b4-8066-9e6a7285efff@kernel.org> In-Reply-To: <60bd3790-f350-44b4-8066-9e6a7285efff@kernel.org> X-Rspamd-Queue-Id: 9A36E40002 X-Stat-Signature: mcen41jcm5uj94okha9nrbtg9fycqz1p X-Rspam-User: X-Rspamd-Server: rspam11 X-HE-Tag: 1786805069-952426 X-HE-Meta: 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 Exu/6NmS +G51dYIib3uS0MZusIru2S15xR7Y4cTv1IhWsbNLRh36dRduPJqDuuOInbFvDoH4Tu0HcyKc0PP54q1CA8gIG6v7QsxENH8W2NypaGjBc9ixrEV8NU90p2K7hWQlSyGBkmoNoZ5ILg4NhpNTlX6i/qg23GXloI9GipeutI+6MgqOIQFuXVlrmL2muC1XqElsZb4eGnsO0o8ODiywLnFVYDOP2JtXhxc+bafLeG9RJU0FIf2tJIYUppNwrooTeaFQVKlwr7SWOGzL/RcIh/ZXF3Hx1igzBci07Ocjxfez7dXYFbN2PP94xTENugwGlbkTVY1DccLrfpbc+cXdkM5PPMZpuXWrEjqCEePf6ey1Bj/F+i/f3aUwQ5QNq6TBu5FTx+/cs3djOH+ZFBY8BdbhfO6WPEQ== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon Aug 3, 2026 at 10:44 AM BST, Vlastimil Babka (SUSE) wrote: > On 7/27/26 00:22, Brendan Jackman wrote: >> This is the minimal solution for ensuring that compaction can service >> unmapped allocations. Without this, it's possible for compaction to just >> check watermarks and see plenty of free pages, without being aware of >> the direct map state, and thereby cause an ALLOC_UNMAPPED allocation to >> fail unnecessarily. >>=20 >> Instead, with this change, promote compact_order to pageblock order for >> unmapped allocations, much like defrag_mode. Then, check specifically in >> compaction for the presence of wholly mapped blocks that can be unmapped >> once direct compact is complete. >>=20 >> This all takes advantage of a major simplification: since unmapped >> blocks are currently always unmovable, this can be asymmetric. There is >> never a need to promote a !ALLOC_UNMAPPED allocation to compacting at >> pageblock_order, because compaction would be trying to generate a >> currently-unmapped block to map; that will always fail because it would >> require migrating unmapped pages, which is not supported at the moment. >>=20 >> Signed-off-by: Brendan Jackman > > Reviewed-by: Vlastimil Babka (SUSE) > > Nit: > >> --- >> mm/compaction.c | 22 ++++++++++++++++++---- >> mm/page_alloc.c | 9 +++++++++ >> 2 files changed, 27 insertions(+), 4 deletions(-) >>=20 >> diff --git a/mm/compaction.c b/mm/compaction.c >> index ed12d2fc6fad3..fe1aaf293bbce 100644 >> --- a/mm/compaction.c >> +++ b/mm/compaction.c >> @@ -2531,12 +2531,25 @@ bool compaction_zonelist_suitable(struct alloc_c= ontext *ac, int order, >> static enum compact_result >> compaction_suit_allocation_order(struct zone *zone, unsigned int order, >> int highest_zoneidx, unsigned int alloc_flags, >> - bool async, bool kcompactd) >> + bool unmapped, bool async, bool kcompactd) > > Instead of the new bool parameter, can we check alloc_flags for ALLOC_UNM= APPED? Lol, yes. I guess I didn't notice alloc_flags was already there :D