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From: Jan Beulich <jbeulich@suse.com>
To: Andrew Cooper <Andrew.Cooper3@citrix.com>
Cc: George Dunlap <George.Dunlap@citrix.com>, Wei Liu <wl@xen.org>,
	Roger Pau Monne <roger.pau@citrix.com>,
	"xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>
Subject: Re: [PATCH 1/2] x86/mm: avoid phys_to_nid() calls for invalid addresses
Date: Mon, 19 Dec 2022 08:14:38 +0100	[thread overview]
Message-ID: <f22869a2-0bba-ffe9-8628-de6787558d6d@suse.com> (raw)
In-Reply-To: <c982fec2-53ba-f448-e073-967925f61bbf@citrix.com>

On 16.12.2022 20:24, Andrew Cooper wrote:
> On 13/12/2022 11:36 am, Jan Beulich wrote:
>> RFC: With small enough a NUMA hash shift it would still be possible to
>>      hit an SRAT hole, despite mfn_valid() passing. Hence, like was the
>>      original plan, it may still be necessary to relax the checking in
>>      phys_to_nid() (or its designated replacements). At which point the
>>      value of this change here would shrink to merely reducing the
>>      chance of unintentionally doing NUMA_NO_NODE allocations.
> 
> Why does the NUMA shift matter?  Can't this occur for badly constructed
> SRAT tables too?

Well, the NUMA hash shift is computed from the SRAT table entries, so
often "badly constructed" => "too small shift".

> Nevertheless, this is a clear improvement over what's currently in tree,
> so I'm going to commit it to try and unblock OSSTest.  The tree has been
> blocked for too long.  Further adjustments can come in due course.

Thanks. And I see it has unblocked the tree.

Jan


  reply	other threads:[~2022-12-19  7:14 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-12-13 11:35 [PATCH 0/2] NUMA: phys_to_nid() related adjustments Jan Beulich
2022-12-13 11:36 ` [PATCH 1/2] x86/mm: avoid phys_to_nid() calls for invalid addresses Jan Beulich
2022-12-14  3:28   ` Wei Chen
2022-12-14  7:44     ` Jan Beulich
2022-12-16 19:24   ` Andrew Cooper
2022-12-19  7:14     ` Jan Beulich [this message]
2022-12-13 11:38 ` [PATCH 2/2] NUMA: replace phys_to_nid() Jan Beulich
2022-12-13 12:06   ` Julien Grall
2022-12-13 12:46     ` Jan Beulich
2022-12-13 13:48       ` Julien Grall
2022-12-13 14:08         ` Jan Beulich
2022-12-13 21:33           ` Julien Grall
2022-12-16 11:49   ` Andrew Cooper
2022-12-16 11:59     ` Jan Beulich
2022-12-16 14:27       ` Andrew Cooper

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