From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f53.google.com (mail-pa0-f53.google.com [209.85.220.53]) by kanga.kvack.org (Postfix) with ESMTP id A04B66B0038 for ; Mon, 16 Mar 2015 22:08:45 -0400 (EDT) Received: by pabyw6 with SMTP id yw6so82355769pab.2 for ; Mon, 16 Mar 2015 19:08:45 -0700 (PDT) Received: from lgeamrelo02.lge.com (lgeamrelo02.lge.com. [156.147.1.126]) by mx.google.com with ESMTP id rb6si25981559pab.79.2015.03.16.19.08.43 for ; Mon, 16 Mar 2015 19:08:44 -0700 (PDT) Date: Tue, 17 Mar 2015 11:08:46 +0900 From: Joonsoo Kim Subject: Re: [PATCH] mm/page_alloc: Call kernel_map_pages in unset_migrateype_isolate Message-ID: <20150317020846.GD19483@js1304-P5Q-DELUXE> References: <1426530585-11367-1-git-send-email-lauraa@codeaurora.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1426530585-11367-1-git-send-email-lauraa@codeaurora.org> Sender: owner-linux-mm@kvack.org List-ID: To: Laura Abbott Cc: Vlastimil Babka , Gioh Kim , 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 On Mon, Mar 16, 2015 at 11:29:45AM -0700, Laura Abbott wrote: > 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. I found that some implementation of kernel_map_pages() in mainline also require this change. Some implementation doesn't check previous state of page table, but some others check previous state of page table when calling kernel_map_pages(). Acked-by: Joonsoo Kim Thanks. > --- > 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 -- 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