From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Hildenbrand Subject: [PATCH v1 1/6] mm/page_alloc: tweak comments in has_unmovable_pages() Date: Tue, 30 Jun 2020 16:26:34 +0200 Message-ID: <20200630142639.22770-2-david@redhat.com> References: <20200630142639.22770-1-david@redhat.com> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20200630142639.22770-1-david@redhat.com> Sender: linux-kernel-owner@vger.kernel.org To: linux-kernel@vger.kernel.org Cc: virtualization@lists.linux-foundation.org, linux-mm@kvack.org, David Hildenbrand , Andrew Morton , Michal Hocko , "Michael S . Tsirkin" List-Id: virtualization@lists.linuxfoundation.org Let's move the split comment regarding bootmem allocations and memory holes, especially in the context of ZONE_MOVABLE, to the PageReserved() check. Cc: Andrew Morton Cc: Michal Hocko Cc: Michael S. Tsirkin Signed-off-by: David Hildenbrand --- mm/page_alloc.c | 22 ++++++---------------- 1 file changed, 6 insertions(+), 16 deletions(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 48eb0f1410d47..bd3ebf08f09b9 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -8207,14 +8207,6 @@ struct page *has_unmovable_pages(struct zone *zone, struct page *page, unsigned long iter = 0; unsigned long pfn = page_to_pfn(page); - /* - * TODO we could make this much more efficient by not checking every - * page in the range if we know all of them are in MOVABLE_ZONE and - * that the movable zone guarantees that pages are migratable but - * the later is not the case right now unfortunatelly. E.g. movablecore - * can still lead to having bootmem allocations in zone_movable. - */ - if (is_migrate_cma_page(page)) { /* * CMA allocations (alloc_contig_range) really need to mark @@ -8233,6 +8225,12 @@ struct page *has_unmovable_pages(struct zone *zone, struct page *page, page = pfn_to_page(pfn + iter); + /* + * Both, bootmem allocations and memory holes are marked + * PG_reserved and are unmovable. We can even have unmovable + * allocations inside ZONE_MOVABLE, for example when + * specifying "movable_core". + */ if (PageReserved(page)) return page; @@ -8306,14 +8304,6 @@ struct page *has_unmovable_pages(struct zone *zone, struct page *page, * it. But now, memory offline itself doesn't call * shrink_node_slabs() and it still to be fixed. */ - /* - * If the page is not RAM, page_count()should be 0. - * we don't need more check. This is an _used_ not-movable page. - * - * The problematic thing here is PG_reserved pages. PG_reserved - * is set to both of a memory hole page and a _used_ kernel - * page at boot. - */ return page; } return NULL; -- 2.26.2