From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ed1-f72.google.com (mail-ed1-f72.google.com [209.85.208.72]) by kanga.kvack.org (Postfix) with ESMTP id 4027F6B0007 for ; Thu, 28 Jun 2018 15:03:39 -0400 (EDT) Received: by mail-ed1-f72.google.com with SMTP id v19-v6so2355926eds.3 for ; Thu, 28 Jun 2018 12:03:39 -0700 (PDT) Received: from mx1.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id l8-v6si3779041edj.379.2018.06.28.12.03.37 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 28 Jun 2018 12:03:38 -0700 (PDT) Date: Thu, 28 Jun 2018 13:21:39 +0200 From: Michal Hocko Subject: Re: [PATCH] mm: hugetlb: yield when prepping struct pages Message-ID: <20180628112139.GC32348@dhcp22.suse.cz> References: <20180627214447.260804-1-cannonmatthews@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180627214447.260804-1-cannonmatthews@google.com> Sender: owner-linux-mm@kvack.org List-ID: To: Cannon Matthews Cc: Andrew Morton , Mike Kravetz , Nadia Yvette Chambers , linux-mm@kvack.org, linux-kernel@vger.kernel.org, andreslc@google.com, pfeiner@google.com, gthelen@google.com On Wed 27-06-18 14:44:47, Cannon Matthews wrote: > 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. This should also apply to reserving the same > amount of memory as 2M pages, as the same number of struct pages > are affected in either case. > > 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. > > Signed-off-by: Cannon Matthews Acked-by: Michal Hocko Thanks! > --- > mm/hugetlb.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > index a963f2034dfc..d38273c32d3b 100644 > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c > @@ -2169,6 +2169,7 @@ static void __init gather_bootmem_prealloc(void) > */ > if (hstate_is_gigantic(h)) > adjust_managed_page_count(page, 1 << h->order); > + cond_resched(); > } > } > > -- > 2.18.0.rc2.346.g013aa6912e-goog -- Michal Hocko SUSE Labs