On Mon, Jun 20, 2022 at 07:06:16PM +0800, Muchun Song wrote: > For now, the feature of hugetlb_free_vmemmap is not compatible with the > feature of memory_hotplug.memmap_on_memory, and hugetlb_free_vmemmap > takes precedence over memory_hotplug.memmap_on_memory. However, someone > wants to make memory_hotplug.memmap_on_memory takes precedence over > hugetlb_free_vmemmap since memmap_on_memory makes it more likely to > succeed memory hotplug in close-to-OOM situations. So the decision > of making hugetlb_free_vmemmap take precedence is not wise and elegant. > The proper approach is to have hugetlb_vmemmap.c do the check whether > the section which the HugeTLB pages belong to can be optimized. If > the section's vmemmap pages are allocated from the added memory block > itself, hugetlb_free_vmemmap should refuse to optimize the vmemmap, > otherwise, do the optimization. Then both kernel parameters are > compatible. So this patch introduces VmemmapSelfHosted to mask any > non-optimizable vmemmap pages. The hugetlb_vmemmap can use this flag > to detect if a vmemmap page can be optimized. > > Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx> > Co-developed-by: Oscar Salvador <osalvador@xxxxxxx> > Signed-off-by: Oscar Salvador <osalvador@xxxxxxx> LGTM, thanks for working on this! -- Oscar Salvador SUSE Labs
