From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:51254 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730795AbeKLFsd (ORCPT ); Mon, 12 Nov 2018 00:48:33 -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, "Linus Torvalds" , "Peter Feiner" , "Greg Thelen" , "Mike Kravetz" , "Andres Lagar-Cavilla" , "Cannon Matthews" , "Michal Hocko" Date: Sun, 11 Nov 2018 19:49:05 +0000 Message-ID: Subject: [PATCH 3.16 226/366] mm: hugetlb: yield when prepping struct pages In-Reply-To: Sender: stable-owner@vger.kernel.org List-ID: 3.16.61-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Cannon Matthews commit 520495fe96d74e05db585fc748351e0504d8f40d upstream. When booting with very large numbers of gigantic (i.e. 1G) pages, the operations in the loop of gather_bootmem_prealloc, and specifically prep_compound_gigantic_page, takes a very long time, and can cause a softlockup if enough pages are requested at boot. For example booting with 3844 1G pages requires prepping (set_compound_head, init the count) over 1 billion 4K tail pages, which takes considerable time. Add a cond_resched() to the outer loop in gather_bootmem_prealloc() to prevent this lockup. Tested: Booted with softlockup_panic=1 hugepagesz=1G hugepages=3844 and no softlockup is reported, and the hugepages are reported as successfully setup. Link: http://lkml.kernel.org/r/20180627214447.260804-1-cannonmatthews@google.com Signed-off-by: Cannon Matthews Reviewed-by: Andrew Morton Reviewed-by: Mike Kravetz Acked-by: Michal Hocko Cc: Andres Lagar-Cavilla Cc: Peter Feiner Cc: Greg Thelen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Ben Hutchings --- mm/hugetlb.c | 1 + 1 file changed, 1 insertion(+) --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -1546,6 +1546,7 @@ static void __init gather_bootmem_preall */ if (hstate_is_gigantic(h)) adjust_managed_page_count(page, 1 << h->order); + cond_resched(); } }