Re: [PATCH v5 4/4] mm: Defer ZONE_DEVICE page initialization to the point where we init pgmap

[Oscar Salvador]

On Fri, Sep 28, 2018 at 10:12:24AM +0200, Oscar Salvador wrote:
> Although I am not sure about leaving memmap_init_zone unprotected.
> For the normal memory, that is not a problem since the memblock's lock
> protects us from touching the same pages at the same time in online/offline_pages,
> but for HMM/devm the story is different.
> 
> I am totally unaware of HMM/devm, so I am not sure if its protected somehow.
> e.g: what happens if devm_memremap_pages and devm_memremap_pages_release are running
> at the same time for the same memory-range (with the assumption that the hotplug-lock
> does not protect move_pfn_range_to_zone anymore).

I guess that this could not happen since the device is not linked to devm_memremap_pages_release
until the end with:

devm_add_action(dev, devm_memremap_pages_release, pgmap)
-- 
Oscar Salvador
SUSE L3