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 e5.ny.us.ibm.com (8.13.8/8.13.8) with ESMTP id mADGsBkO007975 for ; Thu, 13 Nov 2008 11:54:11 -0500 Received: from d01av03.pok.ibm.com (d01av03.pok.ibm.com [9.56.224.217]) by d01relay02.pok.ibm.com (8.13.8/8.13.8/NCO v9.1) with ESMTP id mADGsAlJ177366 for ; Thu, 13 Nov 2008 11:54:10 -0500 Received: from d01av03.pok.ibm.com (loopback [127.0.0.1]) by d01av03.pok.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id mADGs9mO020685 for ; Thu, 13 Nov 2008 11:54:10 -0500 Date: Thu, 13 Nov 2008 08:54:02 -0800 From: Gary Hade Subject: Re: [PATCH] [REPOST #2] mm: show node to memory section relationship with symlinks in sysfs Message-ID: <20081113165402.GA7084@us.ibm.com> References: <20081103234808.GA13716@us.ibm.com> <1226528175.4835.18.camel@badari-desktop> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1226528175.4835.18.camel@badari-desktop> Sender: owner-linux-mm@kvack.org Return-Path: To: Badari Pulavarty Cc: Gary Hade , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton , Yasunori Goto , Mel Gorman , Chris McDermott , Ingo Molnar , Greg KH , Dave Hansen , Nish Aravamudan List-ID: On Wed, Nov 12, 2008 at 02:16:15PM -0800, Badari Pulavarty wrote: > On Mon, 2008-11-03 at 15:48 -0800, Gary Hade wrote: > > Show node to memory section relationship with symlinks in sysfs > > > > Add /sys/devices/system/node/nodeX/memoryY symlinks for all > > the memory sections located on nodeX. For example: > > /sys/devices/system/node/node1/memory135 -> ../../memory/memory135 > > indicates that memory section 135 resides on node1. > > > > Also revises documentation to cover this change as well as updating > > Documentation/ABI/testing/sysfs-devices-memory to include descriptions > > of memory hotremove files 'phys_device', 'phys_index', and 'state' > > that were previously not described there. > > > > In addition to it always being a good policy to provide users with > > the maximum possible amount of physical location information for > > resources that can be hot-added and/or hot-removed, the following > > are some (but likely not all) of the user benefits provided by > > this change. > > Immediate: > > - Provides information needed to determine the specific node > > on which a defective DIMM is located. This will reduce system > > downtime when the node or defective DIMM is swapped out. > > - Prevents unintended onlining of a memory section that was > > previously offlined due to a defective DIMM. This could happen > > during node hot-add when the user or node hot-add assist script > > onlines _all_ offlined sections due to user or script inability > > to identify the specific memory sections located on the hot-added > > node. The consequences of reintroducing the defective memory > > could be ugly. > > - Provides information needed to vary the amount and distribution > > of memory on specific nodes for testing or debugging purposes. > > Future: > > - Will provide information needed to identify the memory > > sections that need to be offlined prior to physical removal > > of a specific node. > > > > Symlink creation during boot was tested on 2-node x86_64, 2-node > > ppc64, and 2-node ia64 systems. Symlink creation during physical > > memory hot-add tested on a 2-node x86_64 system. > > > > Supersedes the "mm: show memory section to node relationship in sysfs" > > patch posted on 05 Sept 2008 which created node ID containing 'node' > > files in /sys/devices/system/memory/memoryX instead of symlinks. > > Changed from files to symlinks due to feedback that symlinks were > > more consistent with the sysfs way. > > > > Supersedes the "mm: show node to memory section relationship with > > symlinks in sysfs" patch posted on 29 Sept 2008 to address a Yasunori > > Goto reported problem where an incorrect symlink was created due to > > a range of uninitialized pages at the beginning of a section. This > > problem which produced a symlink in /sys/devices/system/node/node0 > > that incorrectly referenced a mem section located on node1 is corrected > > in this version. This version also covers the case were a mem section > > could span multiple nodes. > > > > Supersedes the "mm: show node to memory section relationship with > > symlinks in sysfs" patch posted on 09 Oct 2008 to add the Andrew > > Morton requested usefulness information and update to apply cleanly > > to 2.6.28-rc3 and 2.6-git. Code is unchanged. > > > > Signed-off-by: Gary Hade > > Signed-off-by: Badari Pulavarty > > > > Hi Gary, > > While testing latest mmtom (which has this patch) ran into an issue > with sysfs files. What I noticed was, with this patch "memoryXX" > directories in /sys/devices/system/memory/ are not getting cleaned up. > Backing out the patch seems to fix the problem. > > When I tried to remove 64 blocks of memory, empty directories are > stayed around. (look at memory151 - memory215). This is causing OOPS > while trying to add memory block again. I think this could be because > of the symlink added from node directory. Can you look ? Badari, The call to unregister_mem_sect_under_nodes() in remove_memory_block() preceding the removal of the files in the memory section directory _should have_ removed all the symlinks referencing the memory section directory. Did you happen to check to see if the symlinks to memory151-memory215 were still present? Gary -- Gary Hade System x Enablement IBM Linux Technology Center 503-578-4503 IBM T/L: 775-4503 garyhade@us.ibm.com http://www.ibm.com/linux/ltc -- 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