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From: David Hildenbrand <david@redhat.com>
To: Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
	Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@kernel.org>,
	Michal Such?nek <msuchanek@suse.de>,
	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>,
	linuxppc-dev@lists.ozlabs.org, Christopher Lameter <cl@linux.com>,
	Vlastimil Babka <vbabka@suse.cz>, Andi Kleen <ak@linux.intel.com>,
	"Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Subject: Re: [PATCH v5 3/3] mm/page_alloc: Keep memoryless cpuless node 0 offline
Date: Tue, 18 Aug 2020 09:32:52 +0200	[thread overview]
Message-ID: <13a85e52-5caa-24a8-7169-3992b1ad262a@redhat.com> (raw)
In-Reply-To: <20200812060101.GB10992@linux.vnet.ibm.com>

On 12.08.20 08:01, Srikar Dronamraju wrote:
> Hi Andrew, Michal, David
> 
> * Andrew Morton <akpm@linux-foundation.org> [2020-08-06 21:32:11]:
> 
>> On Fri, 3 Jul 2020 18:28:23 +0530 Srikar Dronamraju <srikar@linux.vnet.ibm.com> wrote:
>>
>>>> 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
>>
>> So...  do we merge this patch or not?  Seems that the overall view is
>> "risky but nobody is likely to do anything better any time soon"?
> 
> Can we decide on this one way or the other?

Hmm, not sure who's the person to decide. I tend to prefer doing the
node renaming, handling this in ppc code; looking at the review of v2
there are still some concerns regarding numa distances.

https://patchwork.ozlabs.org/project/linuxppc-dev/patch/20200817103238.158133-1-aneesh.kumar@linux.ibm.com/

-- 
Thanks,

David / dhildenb


WARNING: multiple messages have this Message-ID (diff)
From: David Hildenbrand <david@redhat.com>
To: Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
	Andrew Morton <akpm@linux-foundation.org>
Cc: Gautham R Shenoy <ego@linux.vnet.ibm.com>,
	Andi Kleen <ak@linux.intel.com>,
	linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
	Michal Hocko <mhocko@kernel.org>,
	linux-mm@kvack.org,
	Satheesh Rajendran <sathnaga@linux.vnet.ibm.com>,
	Mel Gorman <mgorman@suse.de>,
	"Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>,
	"Kirill A. Shutemov" <kirill@shutemov.name>,
	Christopher Lameter <cl@linux.com>,
	Michal Such?nek <msuchanek@suse.de>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Vlastimil Babka <vbabka@suse.cz>
Subject: Re: [PATCH v5 3/3] mm/page_alloc: Keep memoryless cpuless node 0 offline
Date: Tue, 18 Aug 2020 09:32:52 +0200	[thread overview]
Message-ID: <13a85e52-5caa-24a8-7169-3992b1ad262a@redhat.com> (raw)
In-Reply-To: <20200812060101.GB10992@linux.vnet.ibm.com>

On 12.08.20 08:01, Srikar Dronamraju wrote:
> Hi Andrew, Michal, David
> 
> * Andrew Morton <akpm@linux-foundation.org> [2020-08-06 21:32:11]:
> 
>> On Fri, 3 Jul 2020 18:28:23 +0530 Srikar Dronamraju <srikar@linux.vnet.ibm.com> wrote:
>>
>>>> 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
>>
>> So...  do we merge this patch or not?  Seems that the overall view is
>> "risky but nobody is likely to do anything better any time soon"?
> 
> Can we decide on this one way or the other?

Hmm, not sure who's the person to decide. I tend to prefer doing the
node renaming, handling this in ppc code; looking at the review of v2
there are still some concerns regarding numa distances.

https://patchwork.ozlabs.org/project/linuxppc-dev/patch/20200817103238.158133-1-aneesh.kumar@linux.ibm.com/

-- 
Thanks,

David / dhildenb


  reply	other threads:[~2020-08-18  7:33 UTC|newest]

Thread overview: 67+ 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 ` 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  9:28   ` Srikar Dronamraju
2020-06-24  9:48   ` Gautham R Shenoy
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  9:28   ` Srikar Dronamraju
2020-06-24 10:29   ` Gautham R Shenoy
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
2020-06-24  9:28   ` Srikar Dronamraju
2020-06-29 14:58   ` Christopher Lameter
2020-06-29 14:58     ` Christopher Lameter
2020-06-29 14:58     ` Christopher Lameter
2020-06-30  4:01     ` Srikar Dronamraju
2020-06-30  4:01       ` Srikar Dronamraju
2020-07-01 12:23       ` Michal Hocko
2020-07-01 12:23         ` Michal Hocko
2020-07-01  8:42   ` Michal Hocko
2020-07-01  8:42     ` Michal Hocko
2020-07-01 10:04     ` Srikar Dronamraju
2020-07-01 10:04       ` Srikar Dronamraju
2020-07-01 10:15       ` David Hildenbrand
2020-07-01 10:15         ` David Hildenbrand
2020-07-01 11:01         ` Srikar Dronamraju
2020-07-01 11:01           ` Srikar Dronamraju
2020-07-01 11:06           ` David Hildenbrand
2020-07-01 11:06             ` David Hildenbrand
2020-07-01 11:30             ` David Hildenbrand
2020-07-01 11:30               ` David Hildenbrand
2020-07-01 12:21               ` Michal Hocko
2020-07-01 12:21                 ` Michal Hocko
2020-07-02  6:44                 ` Srikar Dronamraju
2020-07-02  6:44                   ` Srikar Dronamraju
2020-07-02  8:41                   ` Michal Hocko
2020-07-02  8:41                     ` Michal Hocko
2020-07-02 14:32                     ` Srikar Dronamraju
2020-07-02 14:32                       ` Srikar Dronamraju
2020-07-03  9:10                 ` Michal Suchánek
2020-07-03  9:10                   ` Michal Suchánek
2020-07-03  9:24                   ` Michal Hocko
2020-07-03  9:24                     ` Michal Hocko
2020-07-03 10:59                     ` Michal Hocko
2020-07-03 10:59                       ` Michal Hocko
2020-07-03 11:32                       ` David Hildenbrand
2020-07-03 11:32                         ` David Hildenbrand
2020-07-03 11:46                         ` Michal Hocko
2020-07-03 11:46                           ` Michal Hocko
2020-07-03 12:58                       ` Srikar Dronamraju
2020-07-03 12:58                         ` Srikar Dronamraju
2020-08-07  4:32                         ` Andrew Morton
2020-08-07  4:32                           ` Andrew Morton
2020-08-07  6:58                           ` David Hildenbrand
2020-08-07  6:58                             ` David Hildenbrand
2020-08-07 10:04                             ` Michal Suchánek
2020-08-07 10:04                               ` Michal Suchánek
2020-08-12  6:01                           ` Srikar Dronamraju
2020-08-12  6:01                             ` Srikar Dronamraju
2020-08-18  7:32                             ` David Hildenbrand [this message]
2020-08-18  7:32                               ` David Hildenbrand
2020-08-18  7:37                               ` Michal Hocko
2020-08-18  7:37                                 ` Michal Hocko
2020-08-18  7:49                                 ` Srikar Dronamraju
2020-08-18  7:49                                   ` Srikar Dronamraju
2020-07-06 16:08                     ` Andi Kleen
2020-07-06 16:08                       ` Andi Kleen

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