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 1E75FF34C49 for ; Mon, 13 Apr 2026 13:28:34 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 83A216B0099; Mon, 13 Apr 2026 09:28:33 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 811E66B009B; Mon, 13 Apr 2026 09:28:33 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 700906B009D; Mon, 13 Apr 2026 09:28:33 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id 5D0776B0099 for ; Mon, 13 Apr 2026 09:28:33 -0400 (EDT) Received: from smtpin25.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 27D571A0198 for ; Mon, 13 Apr 2026 13:28:33 +0000 (UTC) X-FDA: 84653612106.25.2719750 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf02.hostedemail.com (Postfix) with ESMTP id 4F00780008 for ; Mon, 13 Apr 2026 13:28:31 +0000 (UTC) Authentication-Results: imf02.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=mQZFa8uj; spf=pass (imf02.hostedemail.com: domain of rppt@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=rppt@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1776086911; 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=MCOqS5Qt7DUErLD1sGM2NitPZa1Tc1bVbjZ/Obd/mdo=; b=I6BWV2bdeoZlklkmn1L9BWRacBKjy/psVM0tQCANj7jDqHtjDVCSkqZhc33nWJNBb4d0Mk GweOCIKKlL8jCyRymqmALckwo9C6AF7oOq5W0o5/BakGMhOUDrngjo+ecZI4+RZdV4eqOY OxzLzmv/MBvfSVSoBHFQYZM9gELdaUQ= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1776086911; a=rsa-sha256; cv=none; b=Moeq6OFoxPhM49ZUX9dunjUFEP9IYqHtyy5j7/wq9G1KKp8yBJnFgW9W3wYE/TRufGQMUe AXb4RVjubx5npBSyynsiq+m5onUHgpgojw20WrN4y/1QofHdYO5h+xzhXczKMInCKJqdwS L6zY/QfGV7jflb5SWgheqbI8Tm8+35o= ARC-Authentication-Results: i=1; imf02.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=mQZFa8uj; spf=pass (imf02.hostedemail.com: domain of rppt@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=rppt@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id 24FA5435E2; Mon, 13 Apr 2026 13:28:30 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1FF49C2BCAF; Mon, 13 Apr 2026 13:28:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1776086910; bh=7VByJTwrbtmSQuR7FvCes1Iak+N/IKd4uFjkgcO39ug=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=mQZFa8ujuVe81yE8vcLgLxhVVWJzt+swKGWZ2ofKQXeOaAczk3K7ksXwrVlaJ+hYw yVXg5XiKV2rDDSHGmZ1cHQ+6AGEE+yBrBY8Yi+AJDfc5p1i4llszFa2XXvV01sTTec G5SA0gcFv2AQ1usMg1UopmrqtMVJnc6aLQ9KCriHB4Wjq3rdjlaeimKxzpGP4Tcub0 Hpe1GUFInfON7xos/qUF6Ek0JOQtQ+M2Mm8BtjbuE4GPPPko8pTQjSqAPoaHfBPtIj Zk8VEGEOVMkuyQZ4NDKGfZm/7c5eMmPrWTp1byTgwQsPAwlXcKcEJE+KRr1I5UgG+L OZ747izg6AIcw== Date: Mon, 13 Apr 2026 16:28:21 +0300 From: Mike Rapoport To: Muchun Song Cc: Muchun Song , Andrew Morton , David Hildenbrand , Oscar Salvador , Michael Ellerman , Madhavan Srinivasan , Lorenzo Stoakes , "Liam R . Howlett" , Vlastimil Babka , Suren Baghdasaryan , Michal Hocko , Nicholas Piggin , Christophe Leroy , aneesh.kumar@linux.ibm.com, joao.m.martins@oracle.com, linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 06/49] mm/mm_init: fix uninitialized pageblock migratetype for ZONE_DEVICE compound pages Message-ID: References: <20260405125240.2558577-1-songmuchun@bytedance.com> <20260405125240.2558577-7-songmuchun@bytedance.com> <5910791C-9893-4710-9002-76534DBFBFBD@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <5910791C-9893-4710-9002-76534DBFBFBD@linux.dev> X-Rspamd-Server: rspam12 X-Stat-Signature: 8xdopu3aomi938ea68ritb9341gjy1ar X-Rspamd-Queue-Id: 4F00780008 X-Rspam-User: X-HE-Tag: 1776086911-196790 X-HE-Meta: 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 +BUqc6hr 9K8L6u4eyedihW83euJlnd5Nn3emKAzUKF0fLJiPsl+3piFYuuF9Y8X3udeMHwkOTe9JTIxA2P8zBXfrkIu8rW/bVU28B9obclhF7IV8tWD5en4dYGhYr32gcksTUEMPPrctlm8tOgKjN3guige+mpBI2xa/aLBG94ogbdqHz/EJgKaA6YLXqDaE+Docxgai1v6ia5IsW/znak7wPRllRsFd3UjSwqV4dN79/Cp9JM4aKR5SZmbWsWPgJnZKJlzVDmUUHQ0fonpdlObcLLdEJJ2Zz/oIFIZPcHHsJKffPQIAuGtEDYQIca9gXpWQuHMkUM86X6D/+NGYcwJk4xnZdnZIpjjaerzhkQIRbH90BhnRqc58Fcl2OXuX8+A== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Apr 13, 2026 at 06:07:44PM +0800, Muchun Song wrote: > > > > On Apr 13, 2026, at 17:32, Mike Rapoport wrote: > > > > On Sun, Apr 05, 2026 at 08:51:57PM +0800, Muchun Song wrote: > >> Previously, memmap_init_zone_device() only initialized the migratetype > >> of the first pageblock of a compound page. If the compound page size > >> exceeds pageblock_nr_pages (e.g., 1GB hugepages with 2MB pageblocks), > >> subsequent pageblocks in the compound page would remain uninitialized. > >> > >> This patch moves the migratetype initialization out of > >> __init_zone_device_page() and into a separate function > >> pageblock_migratetype_init_range(). This function iterates over the > >> entire PFN range of the memory, ensuring that all pageblocks are correctly > >> initialized. > >> > >> Fixes: c4386bd8ee3a ("mm/memremap: add ZONE_DEVICE support for compound pages") > >> Signed-off-by: Muchun Song > >> --- > >> mm/mm_init.c | 41 ++++++++++++++++++++++++++--------------- > >> 1 file changed, 26 insertions(+), 15 deletions(-) > >> > >> diff --git a/mm/mm_init.c b/mm/mm_init.c > >> index 9a44e8458fed..4936ca78966c 100644 > >> --- a/mm/mm_init.c > >> +++ b/mm/mm_init.c > >> @@ -674,6 +674,18 @@ static inline void fixup_hashdist(void) > >> static inline void fixup_hashdist(void) {} > >> #endif /* CONFIG_NUMA */ > >> > >> +static __meminit void pageblock_migratetype_init_range(unsigned long pfn, > >> + unsigned long nr_pages, > >> + int migratetype) > >> +{ > >> + unsigned long end = pfn + nr_pages; > >> + > >> + for (pfn = pageblock_align(pfn); pfn < end; pfn += pageblock_nr_pages) { > >> + init_pageblock_migratetype(pfn_to_page(pfn), migratetype, false); > >> + cond_resched(); > > > > Do we need to call cond_resched() every iteration here? > > Of course not. > > > > >> + } > >> +} > >> + > >> /* > >> * Initialize a reserved page unconditionally, finding its zone first. > >> */ > >> @@ -1011,21 +1023,6 @@ static void __ref __init_zone_device_page(struct page *page, unsigned long pfn, > >> page_folio(page)->pgmap = pgmap; > >> page->zone_device_data = NULL; > >> > >> - /* > >> - * Mark the block movable so that blocks are reserved for > >> - * movable at startup. This will force kernel allocations > >> - * to reserve their blocks rather than leaking throughout > >> - * the address space during boot when many long-lived > >> - * kernel allocations are made. > >> - * > >> - * Please note that MEMINIT_HOTPLUG path doesn't clear memmap > >> - * because this is done early in section_activate() > >> - */ > >> - if (pageblock_aligned(pfn)) { > >> - init_pageblock_migratetype(page, MIGRATE_MOVABLE, false); > >> - cond_resched(); > >> - } > >> - > >> /* > >> * ZONE_DEVICE pages other than MEMORY_TYPE_GENERIC are released > >> * directly to the driver page allocator which will set the page count > >> @@ -1122,6 +1119,8 @@ void __ref memmap_init_zone_device(struct zone *zone, > >> > >> __init_zone_device_page(page, pfn, zone_idx, nid, pgmap); > >> > >> + cond_resched(); > > > > Originally we called cond_resched() once per pageblock, now it's called > > once per page plus for every pageblock in the tight loop that sets the > > migrate type. Isn't it too much? > > There are indeed many more cond_resched() than before, but I don’t have a > concise way to write it, so I took the easy way out. > > How about: > > diff --git a/mm/mm_init.c b/mm/mm_init.c > index 2d680636b67a..d13a2577c4c3 100644 > --- a/mm/mm_init.c > +++ b/mm/mm_init.c > @@ -683,7 +683,8 @@ static __meminit void pageblock_migratetype_init_range(unsigned long pfn, > > for (pfn = pageblock_align(pfn); pfn < end; pfn += pageblock_nr_pages) { > init_pageblock_migratetype(pfn_to_page(pfn), migratetype, isolate); > - cond_resched(); > + if ((pfn & (pageblock_nr_pages * 512 - 1)) == 0) > + cond_resched(); TBH, I don't know if 512 is the right number :) pageblock boundary was a convenient point to have cond_resched() along with setting the migrate type. Here we might be able to squeeze more iterations between subsequent cond_resched() calls. -- Sincerely yours, Mike.