From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pl0-f69.google.com (mail-pl0-f69.google.com [209.85.160.69]) by kanga.kvack.org (Postfix) with ESMTP id 2DE916B0003 for ; Fri, 22 Jun 2018 02:08:18 -0400 (EDT) Received: by mail-pl0-f69.google.com with SMTP id z5-v6so3123883pln.20 for ; Thu, 21 Jun 2018 23:08:18 -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 w130-v6sor1783310pfd.4.2018.06.21.23.08.16 for (Google Transport Security); Thu, 21 Jun 2018 23:08:16 -0700 (PDT) From: Naoya Horiguchi Subject: [PATCH v1] mm: initialize struct page for reserved pages in ZONE_DEVICE Date: Fri, 22 Jun 2018 15:08:03 +0900 Message-Id: <1529647683-14531-1-git-send-email-n-horiguchi@ah.jp.nec.com> Sender: owner-linux-mm@kvack.org List-ID: To: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, Andrew Morton , Michal Hocko , Dan Williams , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Dave Hansen Reading /proc/kpageflags for pfns allocated by pmem namespace triggers kernel panic with a message like "BUG: unable to handle kernel paging request at fffffffffffffffe". The first few pages (controlled by altmap passed to memmap_init_zone()) in the ZONE_DEVICE can skip struct page initialization, which causes the reported issue. This patch simply adds some initialization code for them. Fixes: 4b94ffdc4163 ("x86, mm: introduce vmem_altmap to augment vmemmap_populate()") Signed-off-by: Naoya Horiguchi --- mm/page_alloc.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git v4.17-mmotm-2018-06-07-16-59/mm/page_alloc.c v4.17-mmotm-2018-06-07-16-59_patched/mm/page_alloc.c index 1772513..0b36afe 100644 --- v4.17-mmotm-2018-06-07-16-59/mm/page_alloc.c +++ v4.17-mmotm-2018-06-07-16-59_patched/mm/page_alloc.c @@ -5574,8 +5574,16 @@ void __meminit memmap_init_zone(unsigned long size, int nid, unsigned long zone, * Honor reservation requested by the driver for this ZONE_DEVICE * memory */ - if (altmap && start_pfn == altmap->base_pfn) + if (altmap && start_pfn == altmap->base_pfn) { + unsigned long i; + + for (i = 0; i < altmap->reserve; i++) { + page = pfn_to_page(start_pfn + i); + __init_single_page(page, start_pfn + i, zone, nid); + SetPageReserved(page); + } start_pfn += altmap->reserve; + } for (pfn = start_pfn; pfn < end_pfn; pfn++) { /* -- 2.7.0