Linux-mm Archive on lore.kernel.org
 help / color / Atom feed
From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
To: Michal Hocko <mhocko@kernel.org>
Cc: Michal Such?nek <msuchanek@suse.de>,
	David Hildenbrand <david@redhat.com>,
	Gautham R Shenoy <ego@linux.vnet.ibm.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	Satheesh Rajendran <sathnaga@linux.vnet.ibm.com>,
	Mel Gorman <mgorman@suse.de>,
	"Kirill A. Shutemov" <kirill@shutemov.name>,
	Andrew Morton <akpm@linux-foundation.org>,
	linuxppc-dev@lists.ozlabs.org, Christopher Lameter <cl@linux.com>,
	Vlastimil Babka <vbabka@suse.cz>, Andi Kleen <ak@linux.intel.com>
Subject: Re: [PATCH v5 3/3] mm/page_alloc: Keep memoryless cpuless node 0 offline
Date: Fri, 3 Jul 2020 18:28:23 +0530
Message-ID: <20200703125823.GA26243@linux.vnet.ibm.com> (raw)
In-Reply-To: <20200703105944.GS18446@dhcp22.suse.cz>

* Michal Hocko <mhocko@kernel.org> [2020-07-03 12:59:44]:

> > Honestly, I do not have any idea. I've traced it down to
> > Author: Andi Kleen <ak@suse.de>
> > Date:   Tue Jan 11 15:35:48 2005 -0800
> > 
> >     [PATCH] x86_64: Fix ACPI SRAT NUMA parsing
> > 
> >     Fix fallout from the recent nodemask_t changes. The node ids assigned
> >     in the SRAT parser were off by one.
> > 
> >     I added a new first_unset_node() function to nodemask.h to allocate
> >     IDs sanely.
> > 
> >     Signed-off-by: Andi Kleen <ak@suse.de>
> >     Signed-off-by: Linus Torvalds <torvalds@osdl.org>
> > 
> > which doesn't really tell all that much. The historical baggage and a
> > long term behavior which is not really trivial to fix I suspect.
> 
> Thinking about this some more, this logic makes some sense afterall.
> Especially in the world without memory hotplug which was very likely the
> case back then. It is much better to have compact node mask rather than
> sparse one. After all node numbers shouldn't really matter as long as
> you have a clear mapping to the HW. I am not sure we export that
> information (except for the kernel ring buffer) though.
> 
> The memory hotplug changes that somehow because you can hotremove numa
> nodes and therefore make the nodemask sparse but that is not a common
> case. I am not sure what would happen if a completely new node was added
> and its corresponding node was already used by the renumbered one
> though. It would likely conflate the two I am afraid. But I am not sure
> this is really possible with x86 and a lack of a bug report would
> suggest that nobody is doing that at least.
> 

JFYI,
Satheesh copied in this mailchain had opened a bug a year on crash with vcpu
hotplug on memoryless node. 

https://bugzilla.kernel.org/show_bug.cgi?id=202187

-- 
Thanks and Regards
Srikar Dronamraju


  parent reply index

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-24  9:28 [PATCH v5 0/3] Offline memoryless cpuless node 0 Srikar Dronamraju
2020-06-24  9:28 ` [PATCH v5 1/3] powerpc/numa: Set numa_node for all possible cpus Srikar Dronamraju
2020-06-24  9:48   ` Gautham R Shenoy
2020-06-24  9:28 ` [PATCH v5 2/3] powerpc/numa: Prefer node id queried from vphn Srikar Dronamraju
2020-06-24 10:29   ` Gautham R Shenoy
2020-06-24  9:28 ` [PATCH v5 3/3] mm/page_alloc: Keep memoryless cpuless node 0 offline Srikar Dronamraju
2020-06-29 14:58   ` Christopher Lameter
2020-06-30  4:01     ` Srikar Dronamraju
2020-07-01 12:23       ` Michal Hocko
2020-07-01  8:42   ` Michal Hocko
2020-07-01 10:04     ` Srikar Dronamraju
2020-07-01 10:15       ` David Hildenbrand
2020-07-01 11:01         ` Srikar Dronamraju
2020-07-01 11:06           ` David Hildenbrand
2020-07-01 11:30             ` David Hildenbrand
2020-07-01 12:21               ` Michal Hocko
2020-07-02  6:44                 ` Srikar Dronamraju
2020-07-02  8:41                   ` Michal Hocko
2020-07-02 14:32                     ` Srikar Dronamraju
2020-07-03  9:10                 ` Michal Suchánek
2020-07-03  9:24                   ` Michal Hocko
2020-07-03 10:59                     ` Michal Hocko
2020-07-03 11:32                       ` David Hildenbrand
2020-07-03 11:46                         ` Michal Hocko
2020-07-03 12:58                       ` Srikar Dronamraju [this message]
2020-07-06 16:08                     ` Andi Kleen

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200703125823.GA26243@linux.vnet.ibm.com \
    --to=srikar@linux.vnet.ibm.com \
    --cc=ak@linux.intel.com \
    --cc=akpm@linux-foundation.org \
    --cc=cl@linux.com \
    --cc=david@redhat.com \
    --cc=ego@linux.vnet.ibm.com \
    --cc=kirill@shutemov.name \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=linuxppc-dev@lists.ozlabs.org \
    --cc=mgorman@suse.de \
    --cc=mhocko@kernel.org \
    --cc=msuchanek@suse.de \
    --cc=sathnaga@linux.vnet.ibm.com \
    --cc=torvalds@linux-foundation.org \
    --cc=vbabka@suse.cz \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-mm Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-mm/0 linux-mm/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-mm linux-mm/ https://lore.kernel.org/linux-mm \
		linux-mm@kvack.org
	public-inbox-index linux-mm

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kvack.linux-mm


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git