From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ie0-f177.google.com (mail-ie0-f177.google.com [209.85.223.177]) by kanga.kvack.org (Postfix) with ESMTP id 2E22C6B0032 for ; Mon, 16 Mar 2015 14:30:02 -0400 (EDT) Received: by iecsl2 with SMTP id sl2so178036893iec.1 for ; Mon, 16 Mar 2015 11:30:02 -0700 (PDT) Received: from smtp.codeaurora.org (smtp.codeaurora.org. [198.145.29.96]) by mx.google.com with ESMTPS id n11si12165699ics.17.2015.03.16.11.30.01 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 16 Mar 2015 11:30:01 -0700 (PDT) From: Laura Abbott Subject: [PATCH] mm/page_alloc: Call kernel_map_pages in unset_migrateype_isolate Date: Mon, 16 Mar 2015 11:29:45 -0700 Message-Id: <1426530585-11367-1-git-send-email-lauraa@codeaurora.org> Sender: owner-linux-mm@kvack.org List-ID: To: Joonsoo Kim , Vlastimil Babka , Gioh Kim Cc: Laura Abbott , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Naoya Horiguchi , Mel Gorman , Rik van Riel , Yasuaki Ishimatsu , Zhang Yanfei , Xishi Qiu , Vladimir Davydov , Michal Nazarewicz , Marek Szyprowski Commit 3c605096d315 ("mm/page_alloc: restrict max order of merging on isolated pageblock") changed the logic of unset_migratetype_isolate to check the buddy allocator and explicitly call __free_pages to merge. The page that is being freed in this path never had prep_new_page called so set_page_refcounted is called explicitly but there is no call to kernel_map_pages. With the default kernel_map_pages this is mostly harmless but if kernel_map_pages does any manipulation of the page tables (unmapping or setting pages to read only) this may trigger a fault: alloc_contig_range test_pages_isolated(ceb00, ced00) failed Unable to handle kernel paging request at virtual address ffffffc0cec00000 pgd = ffffffc045fc4000 [ffffffc0cec00000] *pgd=0000000000000000 Internal error: Oops: 9600004f [#1] PREEMPT SMP Modules linked in: exfatfs CPU: 1 PID: 23237 Comm: TimedEventQueue Not tainted 3.10.49-gc72ad36-dirty #1 task: ffffffc03de52100 ti: ffffffc015388000 task.ti: ffffffc015388000 PC is at memset+0xc8/0x1c0 LR is at kernel_map_pages+0x1ec/0x244 Fix this by calling kernel_map_pages to ensure the page is set in the page table properly Fixes: 3c605096d315 ("mm/page_alloc: restrict max order of merging on isolated pageblock") Cc: Naoya Horiguchi Cc: Mel Gorman Cc: Rik van Riel Cc: Yasuaki Ishimatsu Cc: Zhang Yanfei Cc: Xishi Qiu Cc: Vladimir Davydov Cc: Joonsoo Kim Cc: Gioh Kim Cc: Michal Nazarewicz Cc: Marek Szyprowski Cc: Vlastimil Babka Signed-off-by: Laura Abbott --- Note this was found on a backport to 3.10 and the code to make kernel_map_pages change the page table state is currently out of tree. The original had stable, so this may need to go into stable as well. --- mm/page_isolation.c | 1 + 1 file changed, 1 insertion(+) diff --git a/mm/page_isolation.c b/mm/page_isolation.c index 72f5ac3..755a42c 100644 --- a/mm/page_isolation.c +++ b/mm/page_isolation.c @@ -103,6 +103,7 @@ void unset_migratetype_isolate(struct page *page, unsigned migratetype) if (!is_migrate_isolate_page(buddy)) { __isolate_free_page(page, order); + kernel_map_pages(page, (1 << order), 1); set_page_refcounted(page); isolated_page = page; } -- Qualcomm Innovation Center, Inc. Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project This e-mail address will be inactive after March 20, 2015 Please contact privately for follow up after that date. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org