From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f198.google.com (mail-wr0-f198.google.com [209.85.128.198]) by kanga.kvack.org (Postfix) with ESMTP id 6F9C26B0279 for ; Fri, 23 Jun 2017 09:24:40 -0400 (EDT) Received: by mail-wr0-f198.google.com with SMTP id v60so12765330wrc.7 for ; Fri, 23 Jun 2017 06:24:40 -0700 (PDT) Received: from mx1.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id m131si3863758wmb.140.2017.06.23.06.24.38 for (version=TLS1 cipher=AES128-SHA bits=128/128); Fri, 23 Jun 2017 06:24:39 -0700 (PDT) Date: Fri, 23 Jun 2017 15:24:36 +0200 From: Michal Hocko Subject: Re: [patch for-4.12] mm, thp: remove cond_resched from __collapse_huge_page_copy Message-ID: <20170623132436.GA5314@dhcp22.suse.cz> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: David Rientjes Cc: Andrew Morton , Larry Finger , Vlastimil Babka , LKML , linux-mm@kvack.org On Mon 19-06-17 13:43:11, David Rientjes wrote: > This is a partial revert of commit 338a16ba1549 ("mm, thp: copying user > pages must schedule on collapse") which added a cond_resched() to > __collapse_huge_page_copy(). > > On x86 with CONFIG_HIGHPTE, __collapse_huge_page_copy is called in atomic > context and thus scheduling is not possible. This is only a possible > config on arm and i386. > > Although need_resched has been shown to be set for over 100 jiffies while > doing the iteration in __collapse_huge_page_copy, this is better than > doing > > if (in_atomic()) > cond_resched() > > to cover only non-CONFIG_HIGHPTE configs. > > Reported-by: Larry Finger > Signed-off-by: David Rientjes Acked-by: Michal Hocko > --- > Note: Larry should be back as of June 17 to test if this fixes the > reported issue. > > mm/khugepaged.c | 1 - > 1 file changed, 1 deletion(-) > > diff --git a/mm/khugepaged.c b/mm/khugepaged.c > --- a/mm/khugepaged.c > +++ b/mm/khugepaged.c > @@ -652,7 +652,6 @@ static void __collapse_huge_page_copy(pte_t *pte, struct page *page, > spin_unlock(ptl); > free_page_and_swap_cache(src_page); > } > - cond_resched(); > } > } > > > -- > 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 -- Michal Hocko SUSE Labs -- 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