From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail143.messagelabs.com (mail143.messagelabs.com [216.82.254.35]) by kanga.kvack.org (Postfix) with SMTP id 9B6CA6B006A for ; Mon, 11 Jan 2010 18:29:48 -0500 (EST) Date: Mon, 11 Jan 2010 23:29:37 +0000 (GMT) From: Hugh Dickins Subject: Re: [PATCH -mmotm-2010-01-06-14-34] Fix fault count of task in GUP In-Reply-To: <20100111114224.bbf0fc62.minchan.kim@barrios-desktop> Message-ID: References: <20100111114224.bbf0fc62.minchan.kim@barrios-desktop> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org To: Minchan Kim Cc: Andrew Morton , Nick Piggin , linux-mm , lkml List-ID: On Mon, 11 Jan 2010, Minchan Kim wrote: > > get_user_pages calls handle_mm_fault to pin the arguemented > task's page. handle_mm_fault cause major or minor fault and > get_user_pages counts it into task which is passed by argument. > > But the fault happens in current task's context. > So we have to count it not argumented task's context but current > task's one. Have to? current simulates a fault into tsk's address space. It is not a fault into current's address space. I can see that this could be argued either way, or even that such a "fault" should not be counted at all; but I do not see a reason to change the way we have been counting it for years. Sorry, but NAK (to this and to the v2) - unless you have a stronger argument. Hugh > > Signed-off-by: Minchan Kim > CC: Nick Piggin > CC: Hugh Dickins > --- > mm/memory.c | 4 ++-- > 1 files changed, 2 insertions(+), 2 deletions(-) > > diff --git a/mm/memory.c b/mm/memory.c > index 521abf6..2513581 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -1486,9 +1486,9 @@ int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, > BUG(); > } > if (ret & VM_FAULT_MAJOR) > - tsk->maj_flt++; > + current->maj_flt++; > else > - tsk->min_flt++; > + current->min_flt++; > > /* > * The VM_FAULT_WRITE bit tells us that > -- > 1.5.6.3 > > > -- > Kind regards, > Minchan Kim -- 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