Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S938686AbcKNCyL (ORCPT ); Sun, 13 Nov 2016 21:54:11 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:47094 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934226AbcKNCYj (ORCPT ); Sun, 13 Nov 2016 21:24:39 -0500 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Kirill A. Shutemov" , "Michal Hocko" , "Paul Gortmaker" , "Naoya Horiguchi" , "Mike Kravetz" , "Linus Torvalds" , "Jia He" , "Dave Hansen" Date: Mon, 14 Nov 2016 00:14:07 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 054/152] mm/hugetlb: avoid soft lockup in set_max_huge_pages() In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:6f00:88c8:c921:d332 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1722 Lines: 55 3.2.84-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Jia He commit 649920c6ab93429b94bc7c1aa7c0e8395351be32 upstream. In powerpc servers with large memory(32TB), we watched several soft lockups for hugepage under stress tests. The call traces are as follows: 1. get_page_from_freelist+0x2d8/0xd50 __alloc_pages_nodemask+0x180/0xc20 alloc_fresh_huge_page+0xb0/0x190 set_max_huge_pages+0x164/0x3b0 2. prep_new_huge_page+0x5c/0x100 alloc_fresh_huge_page+0xc8/0x190 set_max_huge_pages+0x164/0x3b0 This patch fixes such soft lockups. It is safe to call cond_resched() there because it is out of spin_lock/unlock section. Link: http://lkml.kernel.org/r/1469674442-14848-1-git-send-email-hejianet@gmail.com Signed-off-by: Jia He Reviewed-by: Naoya Horiguchi Acked-by: Michal Hocko Acked-by: Dave Hansen Cc: Mike Kravetz Cc: "Kirill A. Shutemov" Cc: Paul Gortmaker Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings --- mm/hugetlb.c | 4 ++++ 1 file changed, 4 insertions(+) --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -1417,6 +1417,10 @@ static unsigned long set_max_huge_pages( * and reducing the surplus. */ spin_unlock(&hugetlb_lock); + + /* yield cpu to avoid soft lockup */ + cond_resched(); + ret = alloc_fresh_huge_page(h, nodes_allowed); spin_lock(&hugetlb_lock); if (!ret)