Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030246AbbKEDk2 (ORCPT ); Wed, 4 Nov 2015 22:40:28 -0500 Received: from mail-pa0-f68.google.com ([209.85.220.68]:35720 "EHLO mail-pa0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755789AbbKEDk0 (ORCPT ); Wed, 4 Nov 2015 22:40:26 -0500 Date: Thu, 5 Nov 2015 12:41:20 +0900 From: Sergey Senozhatsky To: Minchan Kim Cc: Sergey Senozhatsky , Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Michael Kerrisk , linux-api@vger.kernel.org, Hugh Dickins , Johannes Weiner , Rik van Riel , Mel Gorman , KOSAKI Motohiro , Jason Evans , Daniel Micay , "Kirill A. Shutemov" , Shaohua Li , Michal Hocko , yalin.wang2010@gmail.com Subject: Re: [PATCH v2 01/13] mm: support madvise(MADV_FREE) Message-ID: <20151105034120.GA502@swordfish> References: <1446600367-7976-1-git-send-email-minchan@kernel.org> <1446600367-7976-2-git-send-email-minchan@kernel.org> <20151104021624.GA2476@swordfish> <20151104233910.GA7357@bbox> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20151104233910.GA7357@bbox> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1521 Lines: 40 Hi Minchan, On (11/05/15 08:39), Minchan Kim wrote: [..] > > > > I think it makes sense to update pmd_trans_unstable() and > > pmd_none_or_trans_huge_or_clear_bad() comments in asm-generic/pgtable.h > > Because they explicitly mention MADV_DONTNEED only. Just a thought. > > Hmm, When I read comments(but actually I don't understand it 100%), it > says pmd disappearing from MADV_DONTNEED with mmap_sem read-side > lock. But MADV_FREE doesn't remove the pmd. So, I don't understand > what I should add comment. Please suggest if I am missing something. > Hm, sorry, I need to think about it more, probably my comment is irrelevant. Was fantasizing some stupid use cases like doing MADV_DONTNEED and MADV_FREE on overlapping addresses from different threads, processes that share mem, etc. > > > @@ -379,6 +502,14 @@ madvise_vma(struct vm_area_struct *vma, struct vm_area_struct **prev, > > > return madvise_remove(vma, prev, start, end); > > > case MADV_WILLNEED: > > > return madvise_willneed(vma, prev, start, end); > > > + case MADV_FREE: > > > + /* > > > + * XXX: In this implementation, MADV_FREE works like > > ^^^^ > > XXX > > What does it mean? not much. just a minor note that there is a 'XXX' in "XXX: In this implementation" comment. -ss -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/