Messages in this thread | | | Date | Fri, 14 Nov 2008 16:08:44 -0800 | From | Gary Hade <> | Subject | Re: [PATCH] [REPOST #2] mm: show node to memory section relationship with symlinks in sysfs |
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On Fri, Nov 14, 2008 at 08:41:25AM -0800, Gary Hade wrote: > On Fri, Nov 14, 2008 at 08:05:17AM -0800, Badari Pulavarty wrote: > > On Thu, 2008-11-13 at 08:54 -0800, Gary Hade wrote: > > > 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 <garyhade@us.ibm.com> > > > > > Signed-off-by: Badari Pulavarty <pbadari@us.ibm.com> > > > > > > > > > > > > > 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 > > > > > > > Hi Gary, > > > > As discussed earlier, patch is leaving an extra reference on the > > memoryX directory. Needs a kobject_put() to match the reference > > you get in find_memory_block(). > > Badari, Thanks again for finding that! > > > > > Could you update the patch and resend it ? > > Will do.
I just posted a replacement patch with subject line [PATCH] [REPOST #3] mm: show node to memory section relationship with symlinks in sysfs In addition to addressing the memory section directory removal problem it also contains a change to correct a 'for' loop early termination problem that I noticed while debugging the directory removal problem.
Andrew, If it would be better from a -mm standpoint for me to give you a small patch that would apply on top of instead of replacing the bad one, just let me know.
Thanks, 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
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