[{"id":3677767,"web_url":"http://patchwork.ozlabs.org/comment/3677767/","msgid":"","date":"2026-04-15T17:03:06","subject":"Re: [PATCH v2 6/6] mm/mm_init: Fix pageblock migratetype for\n ZONE_DEVICE compound pages","submitter":{"id":77733,"url":"http://patchwork.ozlabs.org/api/people/77733/","name":"Mike Rapoport","email":"rppt@kernel.org"},"content":"Hi Muchun,\n\nOn Wed, Apr 15, 2026 at 07:14:12PM +0800, Muchun Song wrote:\n> The memmap_init_zone_device() function only initializes the migratetype\n> of the first pageblock of a compound page. If the compound page size\n> exceeds pageblock_nr_pages (e.g., 1GB hugepages with 2MB pageblocks),\n> subsequent pageblocks in the compound page remain uninitialized.\n> \n> Move the migratetype initialization out of __init_zone_device_page()\n> and into a separate pageblock_migratetype_init_range() function. This\n> iterates over the entire PFN range of the memory, ensuring that all\n> pageblocks are correctly initialized.\n> \n> Fixes: c4386bd8ee3a (\"mm/memremap: add ZONE_DEVICE support for compound pages\")\n> Signed-off-by: Muchun Song \n> ---\n> mm/mm_init.c | 42 +++++++++++++++++++++++++++---------------\n> 1 file changed, 27 insertions(+), 15 deletions(-)\n> \n> diff --git a/mm/mm_init.c b/mm/mm_init.c\n> index f9f8e1af921c..30528c4206c1 100644\n> --- a/mm/mm_init.c\n> +++ b/mm/mm_init.c\n> @@ -674,6 +674,19 @@ static inline void fixup_hashdist(void)\n> static inline void fixup_hashdist(void) {}\n> #endif /* CONFIG_NUMA */\n> \n> +static __meminit void pageblock_migratetype_init_range(unsigned long pfn,\n> +\t\t\t\t\t\t unsigned long nr_pages,\n> +\t\t\t\t\t\t int migratetype)\n> +{\n> +\tunsigned long end = pfn + nr_pages;\n> +\n> +\tfor (pfn = pageblock_align(pfn); pfn < end; pfn += pageblock_nr_pages) {\n> +\t\tinit_pageblock_migratetype(pfn_to_page(pfn), migratetype, false);\n> +\t\tif (IS_ALIGNED(pfn, PAGES_PER_SECTION))\n> +\t\t\tcond_resched();\n> +\t}\n> +}\n> +\n> /*\n> * Initialize a reserved page unconditionally, finding its zone first.\n> */\n> @@ -1011,21 +1024,6 @@ static void __ref __init_zone_device_page(struct page *page, unsigned long pfn,\n> \tpage_folio(page)->pgmap = pgmap;\n> \tpage->zone_device_data = NULL;\n> \n> -\t/*\n> -\t * Mark the block movable so that blocks are reserved for\n> -\t * movable at startup. This will force kernel allocations\n> -\t * to reserve their blocks rather than leaking throughout\n> -\t * the address space during boot when many long-lived\n> -\t * kernel allocations are made.\n> -\t *\n> -\t * Please note that MEMINIT_HOTPLUG path doesn't clear memmap\n> -\t * because this is done early in section_activate()\n> -\t */\n> -\tif (pageblock_aligned(pfn)) {\n> -\t\tinit_pageblock_migratetype(page, MIGRATE_MOVABLE, false);\n> -\t\tcond_resched();\n> -\t}\n> -\n> \t/*\n> \t * ZONE_DEVICE pages other than MEMORY_TYPE_GENERIC are released\n> \t * directly to the driver page allocator which will set the page count\n> @@ -1122,6 +1120,8 @@ void __ref memmap_init_zone_device(struct zone *zone,\n> \n> \t\t__init_zone_device_page(page, pfn, zone_idx, nid, pgmap);\n> \n> +\t\tcond_resched();\n> +\n\nI don't think we want cond_resched() for every page here too, even it's a\ncompound page :)\n\nOtherwise\n\nReviewed-by: Mike Rapoport (Microsoft) \n\n> \t\tif (pfns_per_compound == 1)\n> \t\t\tcontinue;\n> \n> @@ -1129,6 +1129,18 @@ void __ref memmap_init_zone_device(struct zone *zone,\n> \t\t\t\t compound_nr_pages(altmap, pgmap));\n> \t}\n> \n> +\t/*\n> +\t * Mark the block movable so that blocks are reserved for\n> +\t * movable at startup. This will force kernel allocations\n> +\t * to reserve their blocks rather than leaking throughout\n> +\t * the address space during boot when many long-lived\n> +\t * kernel allocations are made.\n> +\t *\n> +\t * Please note that MEMINIT_HOTPLUG path doesn't clear memmap\n> +\t * because this is done early in section_activate()\n> +\t */\n> +\tpageblock_migratetype_init_range(start_pfn, nr_pages, MIGRATE_MOVABLE);\n> +\n> \tpr_debug(\"%s initialised %lu pages in %ums\\n\", __func__,\n> \t\tnr_pages, jiffies_to_msecs(jiffies - start));\n> }\n> -- \n> 2.20.1\n>","headers":{"Return-Path":"\n ","X-Original-To":["incoming@patchwork.ozlabs.org","linuxppc-dev@lists.ozlabs.org"],"Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256\n header.s=k20201202 header.b=L06wAtHS;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=lists.ozlabs.org\n (client-ip=112.213.38.117; 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Howlett\" ,\n\tVlastimil Babka ,\n\tSuren Baghdasaryan ,\n\tMichal Hocko , Nicholas Piggin ,\n\tChristophe Leroy , aneesh.kumar@linux.ibm.com,\n\tjoao.m.martins@oracle.com, linux-mm@kvack.org,\n\tlinuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org","Subject":"Re: [PATCH v2 6/6] mm/mm_init: Fix pageblock migratetype for\n ZONE_DEVICE compound pages","Message-ID":"","References":"<20260415111412.1003526-1-songmuchun@bytedance.com>\n <20260415111412.1003526-7-songmuchun@bytedance.com>","X-Mailing-List":"linuxppc-dev@lists.ozlabs.org","List-Id":"","List-Help":"","List-Owner":"","List-Post":"","List-Archive":",\n ","List-Subscribe":",\n ,\n ","List-Unsubscribe":"","Precedence":"list","MIME-Version":"1.0","Content-Type":"text/plain; charset=us-ascii","Content-Disposition":"inline","In-Reply-To":"<20260415111412.1003526-7-songmuchun@bytedance.com>","X-Spam-Status":"No, score=-0.2 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED,\n\tDKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,SPF_HELO_NONE,SPF_PASS\n\tautolearn=disabled version=4.0.1 OzLabs 8","X-Spam-Checker-Version":"SpamAssassin 4.0.1 (2024-03-25) on lists.ozlabs.org"}}]