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Date:   Tue, 15 Sep 2020 12:31:45 +0200
From:   Oscar Salvador <osalvador@suse.de>
To:     Laurent Dufour <ldufour@linux.ibm.com>
Cc:     akpm@linux-foundation.org, David Hildenbrand <david@redhat.com>,
        mhocko@suse.com, Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        linux-mm@kvack.org, "Rafael J . Wysocki" <rafael@kernel.org>,
        nathanl@linux.ibm.com, cheloha@linux.ibm.com,
        Tony Luck <tony.luck@intel.com>,
        Fenghua Yu <fenghua.yu@intel.com>, linux-ia64@vger.kernel.org,
        linux-kernel@vger.kernel.org, stable@vger.kernel.org
Subject: Re: [PATCH v3 2/3] mm: don't rely on system state to detect hot-plug
 operations
Message-ID: <20200915103145.GB30015@linux>
References: <20200915094143.79181-1-ldufour@linux.ibm.com>
 <20200915094143.79181-3-ldufour@linux.ibm.com>
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On Tue, Sep 15, 2020 at 11:41:42AM +0200, Laurent Dufour wrote:
> [1] According to Oscar Salvador, using this qemu command line, ACPI memory
> hotplug operations are raised at SYSTEM_SCHEDULING state:

I would like to stress that this is not the only way we can end up
hotplugging memor while state = SYSTEM_SCHEDULING.
According to David, we can end up doing this if we reboot a VM
with hotplugged memory.
(And I have seen other virtualization technologies do the same)

 
> Fixes: 4fbce633910e ("mm/memory_hotplug.c: make register_mem_sect_under_node() a callback of walk_memory_range()")
> Signed-off-by: Laurent Dufour <ldufour@linux.ibm.com>
> Reviewed-by: David Hildenbrand <david@redhat.com>
> Cc: stable@vger.kernel.org
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: "Rafael J. Wysocki" <rafael@kernel.org>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Michal Hocko <mhocko@suse.com>
> Cc: Oscar Salvador <osalvador@suse.de>

Reviewed-by: Oscar Salvador <osalvador@suse.de>

-- 
Oscar Salvador
SUSE L3