From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from d01relay02.pok.ibm.com (d01relay02.pok.ibm.com [9.56.227.234]) by e6.ny.us.ibm.com (8.13.8/8.13.8) with ESMTP id m2HE6YXQ032467 for ; Mon, 17 Mar 2008 10:06:35 -0400 Received: from d01av04.pok.ibm.com (d01av04.pok.ibm.com [9.56.224.64]) by d01relay02.pok.ibm.com (8.13.8/8.13.8/NCO v8.7) with ESMTP id m2HE4XoW247058 for ; Mon, 17 Mar 2008 10:04:33 -0400 Received: from d01av04.pok.ibm.com (loopback [127.0.0.1]) by d01av04.pok.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id m2HE4Xx4001533 for ; Mon, 17 Mar 2008 10:04:33 -0400 Message-ID: <47DE7A71.1000805@us.ibm.com> Date: Mon, 17 Mar 2008 07:04:33 -0700 From: Badari Pulavarty MIME-Version: 1.0 Subject: Re: grow_dev_page's __GFP_MOVABLE References: <20080312140831.GD6072@csn.ul.ie> <20080313120755.GC12351@csn.ul.ie> <1205420758.19403.6.camel@dyn9047017100.beaverton.ibm.com> <20080313154428.GD12351@csn.ul.ie> <1205455806.19403.47.camel@dyn9047017100.beaverton.ibm.com> <20080314114705.GA18381@csn.ul.ie> <1205510734.19403.53.camel@dyn9047017100.beaverton.ibm.com> <1205520765.19403.59.camel@dyn9047017100.beaverton.ibm.com> <20080317105412.GA3124@shadowen.org> In-Reply-To: <20080317105412.GA3124@shadowen.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Andy Whitcroft Cc: Mel Gorman , Hugh Dickins , Andrew Morton , linux-mm List-ID: Andy Whitcroft wrote: > On Fri, Mar 14, 2008 at 10:52:45AM -0800, Badari Pulavarty wrote: > >> On Fri, 2008-03-14 at 08:05 -0800, Badari Pulavarty wrote: >> >>> On Fri, 2008-03-14 at 11:47 +0000, Mel Gorman wrote: >>> >>>> On (13/03/08 16:50), Badari Pulavarty didst pronounce: >>>> >>>>>>> >>>>>>> page_owner shows: >>>>>>> >>>>>>> Page allocated via order 0, mask 0x120050 >>>>>>> PFN 30625 Block 7 type 2 Flags L >>>>>>> >>>>>> This page is indicated as being on the LRU so it should have been possible >>>>>> to reclaim. Is memory hot-remove making any effort to reclaim this page or >>>>>> is it depending only on page migration? >>>>>> >>>>> offline_pages() finds all the pages on LRU and tries to migrate them by >>>>> calling unmap_and_move(). I don't see any explicit attempt to reclaim. >>>>> It tries to migrate the page (move_to_new_page()), but what I have seen >>>>> in the past is that these pages have buffer heads attached to them. >>>>> So, migrate_page_move_mapping() fails to release the page. (BTW, >>>>> I narrowed this in Oct 2007 and forgot most of the details). I can >>>>> take a closer look again. Can we reclaim these pages easily ? >>>>> >>>>> >>>> They should be, or huge page allocations using lumpy reclaim would also >>>> be failing all the time. >>>> >>> Hi Mel, >>> >>> These pages are on LRU and clean. In order to reclaim these pages >>> (looking at pageout()), all we need to do is try_to_release_page(). >>> fallback_migrate_page() does this but fails to free it up. What >>> else I can do here to force reclaim these ? >>> >> In other words, caller has a ref on the buffer_head by calling >> getblk(). So, try_to_release_page() would fail since buffer_busy(). >> These buffers could be holding meta-data (super block, bitmaps etc.) >> for a file system. Till fs gets rid of the ref, there is nothing >> much we can do. Isn't it ? >> > > Cirtainly when fragmentation avoidance was young we did see a lot of > this as some of the meta-data was badly marked. What filesystem is this > running on? > > -apw > I have seen this with reiserfs and ext3. Thanks, Badari -- 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