From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f200.google.com (mail-wr0-f200.google.com [209.85.128.200]) by kanga.kvack.org (Postfix) with ESMTP id 0CF746B0006 for ; Fri, 22 Jun 2018 12:28:50 -0400 (EDT) Received: by mail-wr0-f200.google.com with SMTP id j8-v6so4645908wrh.18 for ; Fri, 22 Jun 2018 09:28:50 -0700 (PDT) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id z12-v6sor4097331wrn.56.2018.06.22.09.28.48 for (Google Transport Security); Fri, 22 Jun 2018 09:28:48 -0700 (PDT) From: Michal Hocko Subject: [PATCH] mm: drop VM_BUG_ON from __get_free_pages Date: Fri, 22 Jun 2018 18:28:41 +0200 Message-Id: <20180622162841.25114-1-mhocko@kernel.org> Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: JianKang Chen , Mel Gorman , Johannes Weiner , linux-mm@kvack.org, linux-kernel@vger.kernel.org, xieyisheng1@huawei.com, guohanjun@huawei.com, wangkefeng.wang@huawei.com, Michal Hocko From: Michal Hocko There is no real reason to blow up just because the caller doesn't know that __get_free_pages cannot return highmem pages. Simply fix that up silently. Even if we have some confused users such a fixup will not be harmful. Signed-off-by: Michal Hocko --- Hi Andrew, previously posted [1] but it fell through cracks. Can we merge it now? [1] http://lkml.kernel.org/r/20171129160446.jluzpv3n6mjc3fwv@dhcp22.suse.cz mm/page_alloc.c | 10 +++------- 1 file changed, 3 insertions(+), 7 deletions(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 1521100f1e63..5f56f662a52d 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -4402,18 +4402,14 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order, int preferred_nid, EXPORT_SYMBOL(__alloc_pages_nodemask); /* - * Common helper functions. + * Common helper functions. Never use with __GFP_HIGHMEM because the returned + * address cannot represent highmem pages. Use alloc_pages and then kmap if + * you need to access high mem. */ unsigned long __get_free_pages(gfp_t gfp_mask, unsigned int order) { struct page *page; - /* - * __get_free_pages() returns a virtual address, which cannot represent - * a highmem page - */ - VM_BUG_ON((gfp_mask & __GFP_HIGHMEM) != 0); - page = alloc_pages(gfp_mask, order); if (!page) return 0; -- 2.17.1