Re: [RFC PATCH v3 3/8] mm: migrate: allocate the right size of non hugetlb or THP compound pages.
From: David Hildenbrand <hidden>
Date: 2022-01-13 15:50:49
Also in:
linux-iommu, linux-mm, lkml, virtualization
On 13.01.22 16:46, Zi Yan wrote:
On 12 Jan 2022, at 6:04, David Hildenbrand wrote:quoted
On 05.01.22 22:47, Zi Yan wrote:quoted
From: Zi Yan <ziy@nvidia.com> alloc_migration_target() is used by alloc_contig_range() and non-LRU movable compound pages can be migrated. Current code does not allocate the right page size for such pages. Check THP precisely using is_transparent_huge() and add allocation support for non-LRU compound pages.IIRC, we don't have any non-lru migratable pages that are coumpound pages. Read: not used and not supported :)OK, but nothing prevents one writing a driver that allocates compound pages and provides address_space->migratepage() and address_space->isolate_page(). Actually, to test this series, I write a kernel module that allocates an order-10 page, gives it a fake address_space with migratepage() and isolate_page(), __SetPageMovable() on it, then call alloc_contig_range() on the page range. Apparently, my kernel module is not supported by the kernel, thus, I added this patch. Do you have an alternative test to my kernel module, so that I do not even need this patch myself?quoted
Why is this required in the context of this series?It might not be required. I will drop it.
That's why I think it would be best dropping it. If you need it in different context, better submit it in different context. Makes this series easier to digest :) -- Thanks, David / dhildenb