From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 59CBB18AFE for ; Mon, 13 Apr 2026 09:32:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776072758; cv=none; b=R0y6dDDgVoUSGgja2r/3brKdwUrN77eAmxjKxToiIoGGwVRpJTozqftxKiH90SH3/QE12X3lJkBVsPq9UTNkX40uEvz3zKt/WgH0A9Z0tEBNVNmkB4K1QW9NnCIBWxsekBo8sMiu0kyw4N0+oIQLao/SijkBokrZpOjUegO/0ZU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776072758; c=relaxed/simple; bh=JRZWemltksdWoEBhaBDF2gLrvxOl6lymdz6gK0hrGbE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=AoQPW8TwrrIPpUIU4ocMVdoCFasih+iDd8BXErcD7uZ7E/pMUGDNLQZTyNiLPGL98OEnDXtqWY7HOuCgVcj18olOOlr2dd7hXceLzq6XcaXdmNxy5D8jXS7+rMwKhFel2XH0u2Ak/THrT1G6nuQ9tG57d2RS8ufnxo+9WDBZG/E= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=tNn9OWyN; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="tNn9OWyN" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7F6FAC116C6; Mon, 13 Apr 2026 09:32:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1776072758; bh=JRZWemltksdWoEBhaBDF2gLrvxOl6lymdz6gK0hrGbE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=tNn9OWyN2iOjVuYi6CPt63fahnmPUSEpc9OBeODdPvpBmVWVqEJ9VkP/s3F3/LkWc M3D6XOlui3DwCNa/oRFVZYcFelpdBxw1uzz2hyPoj9IeevEzAwY4gfIg9vLVwkRUjN 1o9lyi5gDuYluIyQ7YS3c+gqJMTJElNAfV2DFF6S5DMap2bmm50mlJdjs1nzl61nrp GCd9cHivlBrgRl4bJ/YXyhK06h7Zhzwg0lrqFtnA8fQqNdMFgrcUPHOa8To2zbUdwo HylUc08gkSGh8JQFkgI56dvl+nF8OSz4o1mp/5aTj4GMZWDP20ZX+UrfAB1EBa7Caq U0B3CRA5lKHxQ== Date: Mon, 13 Apr 2026 12:32:28 +0300 From: Mike Rapoport To: Muchun Song Cc: Andrew Morton , David Hildenbrand , Muchun Song , 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> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260405125240.2558577-7-songmuchun@bytedance.com> 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? > + } > +} > + > /* > * 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? > + > if (pfns_per_compound == 1) > continue; > > @@ -1129,6 +1128,18 @@ void __ref memmap_init_zone_device(struct zone *zone, > compound_nr_pages(altmap, pgmap)); > } > > + /* > + * 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() > + */ > + pageblock_migratetype_init_range(start_pfn, nr_pages, MIGRATE_MOVABLE); > + > pr_debug("%s initialised %lu pages in %ums\n", __func__, > nr_pages, jiffies_to_msecs(jiffies - start)); > } > -- > 2.20.1 > -- Sincerely yours, Mike.