Messages in this thread | | | Date | Thu, 27 Sep 2018 14:32:54 +0200 | From | Oscar Salvador <> | Subject | Re: [PATCH v5 4/4] mm: Defer ZONE_DEVICE page initialization to the point where we init pgmap |
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On Wed, Sep 26, 2018 at 11:25:37AM -0700, Alexander Duyck wrote: > With that said I am open to suggestions if you still feel like I need to > follow this up with some additional work. I just want to avoid introducing > any regressions in regards to functionality or performance.
Hi Alexander,
the problem I see is that devm/hmm is using some of the memory-hotplug features, but their paths are becoming more and more diverged with changes like this, and that is sometimes a problem when we need to change something in the generic memory-hotplug code.
E.g: I am trying to fix two issues in the memory-hotplug where we can access steal pages if we hot-remove memory before online it. That was not so difficult to fix, but I really struggled with the exceptions that HMM/devm represent in this regard, for instance, regarding the resources.
The RFCv2 can be found here [1] https://patchwork.kernel.org/patch/10569083/ And the initial discussion with Jerome Glisse can be found here [2].
So it would be great to stick to the memory-hotplug path as much as possible, otherwise when a problem arises, we need to think how we can workaround HMM/devm.
[1] https://patchwork.kernel.org/patch/10569083/ [2] https://patchwork.kernel.org/patch/10558725/
-- Oscar Salvador SUSE L3
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