linux-kernel - Re: [PATCH v6 03/10] mm/memory_hotplug: Don't access uninitialized memmaps in shrink_pgdat

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Message-ID: <3d8be627-bfd6-1336-689d-345a2ed67118@redhat.com>
Date:   Mon, 14 Oct 2019 11:31:14 +0200
From:   David Hildenbrand <david@...hat.com>
To:     linux-kernel@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     linux-mm@...ck.org, linux-arm-kernel@...ts.infradead.org,
        linux-ia64@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        linux-s390@...r.kernel.org, linux-sh@...r.kernel.org,
        x86@...nel.org, Oscar Salvador <osalvador@...e.de>,
        Michal Hocko <mhocko@...e.com>,
        Pavel Tatashin <pasha.tatashin@...een.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Wei Yang <richardw.yang@...ux.intel.com>,
        "Aneesh Kumar K . V" <aneesh.kumar@...ux.ibm.com>
Subject: Re: [PATCH v6 03/10] mm/memory_hotplug: Don't access uninitialized
 memmaps in shrink_pgdat_span()

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@...ux-foundation.org>
> Cc: Oscar Salvador <osalvador@...e.de>
> Cc: David Hildenbrand <david@...hat.com>
> Cc: Michal Hocko <mhocko@...e.com>
> Cc: Pavel Tatashin <pasha.tatashin@...een.com>
> Cc: Dan Williams <dan.j.williams@...el.com>
> Cc: Wei Yang <richardw.yang@...ux.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@...r.kernel.org # v4.13+

-- 

Thanks,

David / dhildenb