Messages in this thread | | | Date | Fri, 30 Jun 2017 20:57:50 -0400 | From | Jerome Glisse <> | Subject | Re: [HMM 12/15] mm/migrate: new memory migration helper for use with device memory v4 |
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On Fri, Jun 30, 2017 at 04:19:25PM -0700, Evgeny Baskakov wrote: > Hi Jerome, > > It seems that the kernel can pass 0 in src_pfns for pages that it cannot > migrate (i.e. the kernel knows that they cannot migrate prior to calling > alloc_and_copy). > > So, a zero in src_pfns can mean either "the page is not allocated yet" or > "the page cannot migrate". > > Can migrate_vma set the MIGRATE_PFN_MIGRATE flag for not allocated pages? On > the driver side it is difficult to differentiate between the cases.
So this is what is happening in v24. For thing that can not be migrated you get 0 and for things that are not allocated you get MIGRATE_PFN_MIGRATE like the updated comments in migrate.h explain.
Cheers, Jérôme
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