From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f200.google.com (mail-wr0-f200.google.com [209.85.128.200]) by kanga.kvack.org (Postfix) with ESMTP id 7588C6B025E for ; Thu, 14 Dec 2017 08:05:17 -0500 (EST) Received: by mail-wr0-f200.google.com with SMTP id f4so3192641wre.9 for ; Thu, 14 Dec 2017 05:05:17 -0800 (PST) Received: from mx2.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id b15si3258776wrh.303.2017.12.14.05.05.15 for (version=TLS1 cipher=AES128-SHA bits=128/128); Thu, 14 Dec 2017 05:05:16 -0800 (PST) Date: Thu, 14 Dec 2017 14:04:35 +0100 From: Michal Hocko Subject: Re: [PATCH V2] mm/mprotect: Add a cond_resched() inside change_pmd_range() Message-ID: <20171214130435.GL16951@dhcp22.suse.cz> References: <20171214111426.25912-1-khandual@linux.vnet.ibm.com> <20171214112928.GH16951@dhcp22.suse.cz> <28e54a80-73d9-76aa-31d5-f71375f14b96@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <28e54a80-73d9-76aa-31d5-f71375f14b96@linux.vnet.ibm.com> Sender: owner-linux-mm@kvack.org List-ID: To: Anshuman Khandual Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org On Thu 14-12-17 18:25:54, Anshuman Khandual wrote: > On 12/14/2017 04:59 PM, Michal Hocko wrote: > > On Thu 14-12-17 16:44:26, Anshuman Khandual wrote: > >> diff --git a/mm/mprotect.c b/mm/mprotect.c > >> index ec39f73..43c29fa 100644 > >> --- a/mm/mprotect.c > >> +++ b/mm/mprotect.c > >> @@ -196,6 +196,7 @@ static inline unsigned long change_pmd_range(struct vm_area_struct *vma, > >> this_pages = change_pte_range(vma, pmd, addr, next, newprot, > >> dirty_accountable, prot_numa); > >> pages += this_pages; > >> + cond_resched(); > >> } while (pmd++, addr = next, addr != end); > >> > >> if (mni_start) > > > > this is not exactly what I meant. See how change_huge_pmd does continue. > > That's why I mentioned zap_pmd_range which does goto next... > > I might be still missing something but is this what you meant ? yes, except > Here we will give cond_resched() cover to the THP backed pages > as well. but there is still if (!is_swap_pmd(*pmd) && !pmd_trans_huge(*pmd) && !pmd_devmap(*pmd) && pmd_none_or_clear_bad(pmd)) continue; so we won't have scheduling point on pmd holes. Maybe this doesn't matter, I haven't checked but why should we handle those differently? > diff --git a/mm/mprotect.c b/mm/mprotect.c > index ec39f73..3d445ee 100644 > --- a/mm/mprotect.c > +++ b/mm/mprotect.c > @@ -188,7 +188,7 @@ static inline unsigned long change_pmd_range(struct vm_area_struct *vma, > } > > /* huge pmd was handled */ > - continue; > + goto next; > } > } > /* fall through, the trans huge pmd just split */ > @@ -196,6 +196,8 @@ static inline unsigned long change_pmd_range(struct vm_area_struct *vma, > this_pages = change_pte_range(vma, pmd, addr, next, newprot, > dirty_accountable, prot_numa); > pages += this_pages; > +next: > + cond_resched(); > } while (pmd++, addr = next, addr != end); > > if (mni_start) -- 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