From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with ESMTP id 29AFC6B01BD for ; Fri, 28 May 2010 12:40:43 -0400 (EDT) Message-ID: <4BFFF1DF.3020501@cray.com> Date: Fri, 28 May 2010 09:39:59 -0700 From: Doug Doan MIME-Version: 1.0 Subject: Re: [PATCH] hugetlb: call mmu notifiers on hugepage cow References: <4BFED954.8060807@cray.com> <20100528095946.GB9774@csn.ul.ie> In-Reply-To: <20100528095946.GB9774@csn.ul.ie> Content-Type: text/plain; charset="ISO-8859-15"; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Mel Gorman Cc: "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , "andi@firstfloor.org" , "lee.schermerhorn@hp.com" , "rientjes@google.com" , "akpm@linux-foundation.org" List-ID: On 05/28/2010 02:59 AM, Mel Gorman wrote: > On Thu, May 27, 2010 at 01:43:00PM -0700, Doug Doan wrote: >> From: Doug Doan >> >> When a copy-on-write occurs, we take one of two paths in handle_mm_fault: >> through handle_pte_fault for normal pages, or through hugetlb_fault for >> huge pages. >> >> In the normal page case, we eventually get to do_wp_page and call mmu >> notifiers via ptep_clear_flush_notify. There is no callout to the mmmu >> notifiers in the huge page case. This patch fixes that. >> >> Signed-off-by: Doug Doan >> --- > >> --- mm/hugetlb.c.orig 2010-05-27 13:07:58.569546314 -0700 >> +++ mm/hugetlb.c 2010-05-26 14:41:06.449296524 -0700 >> @@ -2345,11 +2345,17 @@ retry_avoidcopy: >> ptep = huge_pte_offset(mm, address& huge_page_mask(h)); >> if (likely(pte_same(huge_ptep_get(ptep), pte))) { >> /* Break COW */ >> + mmu_notifier_invalidate_range_start(mm, >> + address& huge_page_mask(h), >> + (address& huge_page_mask(h)) + huge_page_size(h)); > > Should the address not already be aligned? I'm not seeing where the address was aligned before this point. The code just above aligns it: ptep = huge_pte_offset(mm, address& huge_page_mask(h)); if (likely(pte_same(huge_ptep_get(ptep), pte))) { /* Break COW */ > Otherwise, I don't see any problem. > >> huge_ptep_clear_flush(vma, address, ptep); >> set_huge_pte_at(mm, address, ptep, >> make_huge_pte(vma, new_page, 1)); >> /* Make the old page be freed below */ >> new_page = old_page; >> + mmu_notifier_invalidate_range_end(mm, >> + address& huge_page_mask(h), >> + (address& huge_page_mask(h)) + huge_page_size(h)); >> } >> page_cache_release(new_page); >> page_cache_release(old_page); > > -- 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