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 6AA81C5DF67 for ; Sat, 15 Aug 2026 14:30:55 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 7C6026B07CC; Sat, 15 Aug 2026 10:30:54 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 776076B07CD; Sat, 15 Aug 2026 10:30:54 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 68B326B07CE; Sat, 15 Aug 2026 10:30:54 -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 41BE86B07CC for ; Sat, 15 Aug 2026 10:30:54 -0400 (EDT) Received: from smtpin08.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay09.hostedemail.com (Postfix) with ESMTP id C3F7E803A6 for ; Sat, 15 Aug 2026 14:30:53 +0000 (UTC) X-FDA: 85103740386.08.8F5796B Received: from mta0.migadu.com (out-112.mta0.migadu.com [91.218.175.112]) by imf29.hostedemail.com (Postfix) with ESMTP id C355D120006 for ; Sat, 15 Aug 2026 14:30:51 +0000 (UTC) Authentication-Results: imf29.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=Ex1nmzfE; spf=pass (imf29.hostedemail.com: domain of brendan.jackman@linux.dev designates 91.218.175.112 as permitted sender) smtp.mailfrom=brendan.jackman@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1786804252; b=S2zytFvdoH427mO+ofQ6nTLEYXnrk7OZIFr0YK1G7kFwmmbugnEubVBCmgNJ8kceCEjQm2 mxusCHhxZfmYuRYGColwfGYwR1fbXH9fI3NDLlU8MYcuV+rZhADy/wR86SLYMaG7VOdDwc ZHFzy37XdQ+le8FGVgBDD5gKrVjhJfI= ARC-Authentication-Results: i=1; imf29.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=Ex1nmzfE; spf=pass (imf29.hostedemail.com: domain of brendan.jackman@linux.dev designates 91.218.175.112 as permitted sender) smtp.mailfrom=brendan.jackman@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1786804252; 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=/0Z/2LadPFY3rjFZ+EZ/aup+JHhu6t6XpboK+FK8giU=; b=A9VsK2A/MZATJT42/Vx+TTlTA1zFSQzwo5kjw/9VWej6iDIhza+GfYjrTll/Clhzc4Keuk 9s/UtozecVcUA3Ol6cW01MtxQWc1JZ20OAHPowuc1EoiZ4cCSCZJr2rWiB0PFxwUQxWI9h hf4DvVg1dF3frxSZDqy9MvgWeEGI+ro= X-Envelope-To: linux-mm@kvack.org DKIM-Signature: a=rsa-sha256; bh=f0l24nJdKCPn3HKZrSe3W0vzuVprJAb/6eQIXz+8b4s=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1786804250; v=1; x=1787409050; b=Ex1nmzfE9iGXU5fCmahNyVytG7kca6ipEWwEzWtf0vrvM/wpyjFCaoBLJqYjYnexwQpYFLNq khPZE/FHwgZxmh4xvv/X5IevlsbrGNds5D6v8H/J8w7pFZVbM+UsuUlQa1+oqz22SqeXUikWLto RFurkYXa3v8WU8MfeX2grlxo= X-Envelope-To: linux-mm@kvack.org Received: from localhost (77.97.51.77) by smtp.migadu.com with ESMTPS id aa0f9b3bd3bb642c; Sat, 15 Aug 2026 14:30:49 +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 15:30:44 +0100 Message-Id: Cc: "Borislav Petkov" , "Dave Hansen" , "Peter Zijlstra" , "Andrew Morton" , "David Hildenbrand" , "Vlastimil Babka" , "Mike Rapoport" , "Wei Xu" , "Johannes Weiner" , "Zi Yan" , "Lorenzo Stoakes" , , , , "Sumit Garg" , "Will Deacon" , , , "Itazuri, Takahiro" , "Andy Lutomirski" , "David Kaplan" , "Thomas Gleixner" , "Patrick Bellasi" , "Reiji Watanabe" , "Sean Christopherson" Subject: Re: [PATCH v3 21/26] mm/page_alloc: implement FREETYPE_UNMAPPED allocations From: "Brendan Jackman" To: "Yosry Ahmed" X-Mailer: aerc 0.21.0 References: <20260726-page_alloc-unmapped-v3-0-6f5729aa9832@google.com> <20260726-page_alloc-unmapped-v3-21-6f5729aa9832@google.com> In-Reply-To: X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: C355D120006 X-Stat-Signature: y985s31hbdrtrrtd3hygf3jn8f1cugsr X-HE-Tag: 1786804251-468997 X-HE-Meta: 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 Gcxwf5br iUkoqUBWkKBO3u7nEV7qeHnR+QQE7+K49p2lGPE6C7uidvEuj1Ltfjy9zP4ZhhqZAh3UZjTbYSTeBOSaMq2kQLwiOYKus3veC3hnYkaVA7LfJ2mUme1kNwfkAzga6QLUgTV82jxUG+MSDK5T4ofq82vM5holocfxxjYqw/s/KRgXvdRD/R1b1ZLBmqoZ68Lj0S2rNZDlxZVdXqEZ1IKZxG9L0WyCigV9j/OZ3EXZS7hiM7Bkh4n65cRKA1mnEaY/7mCZAz0o1EmmX1zGrGhFTyVJrziLZDVbFipEqQm2EjQ1ujAvvq3fwVoBQlUuBqHfH8ayPM0DkJ2ftXLSPqy0N8k+QyXtAwVWq61qBLy3N9pCSag0= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri Aug 7, 2026 at 1:16 AM BST, Yosry Ahmed wrote: >> diff --git a/mm/compaction.c b/mm/compaction.c >> index 67b01af024e17..c9eb3947ffc79 100644 >> --- a/mm/compaction.c >> +++ b/mm/compaction.c >> @@ -1393,6 +1393,9 @@ static bool suitable_migration_source(struct compa= ct_control *cc, >> block_ft =3D get_pageblock_freetype(page); >> block_mt =3D free_to_migratetype(block_ft); >> >> + if (freetype_unmapped(get_pageblock_freetype(page))) >> + return false; >> + >> /* >> * CMA pages can only be taken by ALLOC_CMA requests. For anybod= y >> * else, vacating a CMA block consumes free pages the caller >> @@ -1444,6 +1447,9 @@ static bool suitable_migration_target(struct compa= ct_control *cc, >> return false; >> } >> >> + if (freetype_unmapped(get_pageblock_freetype(page))) >> + return false; >> + > > Do we also want to add safety checks in the page migration code? IIUC, > if we miss a check in the compaction code and try to compact an > unmapped pageblock the kernel will crash with a #PF in supervisor > mode. Shrug, yeah I would certainly be happy with sprinkling some more if (WARN_ON(freetype_unmapped(...))) return -1; here and there. But yeah this feels like a maintainer preference / philosophy question :D If the machine is gonna crash quite clearly anyway maybe it's not worth it, I dunno. >> if (cc->ignore_block_suitable) >> return true; >>