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Subject: Re: [PATCH v6 03/10] mm/memory_hotplug: Don't access uninitialized
 memmaps in shrink_pgdat_span()
To: linux-kernel@vger.kernel.org, Andrew Morton <akpm@linux-foundation.org>
References: <20191006085646.5768-1-david@redhat.com>
 <20191006085646.5768-4-david@redhat.com>
From: David Hildenbrand <david@redhat.com>
Organization: Red Hat GmbH
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Date: Mon, 14 Oct 2019 11:31:14 +0200
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Cc: linux-s390@vger.kernel.org, Michal Hocko <mhocko@suse.com>,
 linux-ia64@vger.kernel.org, Pavel Tatashin <pasha.tatashin@soleen.com>,
 linux-sh@vger.kernel.org, "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>,
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 <linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org>

On 06.10.19 10:56, David Hildenbrand wrote:
> We might use the nid of memmaps that were never initialized. For
> example, if the memmap was poisoned, we will crash the kernel in
> pfn_to_nid() right now. Let's use the calculated boundaries of the separate
> zones instead. This now also avoids having to iterate over a whole bunch of
> subsections again, after shrinking one zone.
> 
> Before commit d0dc12e86b31 ("mm/memory_hotplug: optimize memory
> hotplug"), the memmap was initialized to 0 and the node was set to the
> right value. After that commit, the node might be garbage.
> 
> We'll have to fix shrink_zone_span() next.
> 
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Oscar Salvador <osalvador@suse.de>
> Cc: David Hildenbrand <david@redhat.com>
> Cc: Michal Hocko <mhocko@suse.com>
> Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
> Cc: Dan Williams <dan.j.williams@intel.com>
> Cc: Wei Yang <richardw.yang@linux.intel.com>
> Fixes: d0dc12e86b31 ("mm/memory_hotplug: optimize memory hotplug")

@Andrew, can you convert that to

Fixes: f1dd2cd13c4b ("mm, memory_hotplug: do not associate hotadded memory to zones until online") # visible after d0dc12e86b319

and add

Cc: stable@vger.kernel.org # v4.13+

-- 

Thanks,

David / dhildenb