Messages in this thread | | | Subject | Re: [PATCH] mm: Introduce GFP_PGTABLE | From | Anshuman Khandual <> | Date | Mon, 14 Jan 2019 09:30:55 +0530 |
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On 01/13/2019 11:05 PM, Michal Hocko wrote: > On Sat 12-01-19 15:56:38, Anshuman Khandual wrote: >> All architectures have been defining their own PGALLOC_GFP as (GFP_KERNEL | >> __GFP_ZERO) and using it for allocating page table pages. This causes some >> code duplication which can be easily avoided. GFP_KERNEL allocated and >> cleared out pages (__GFP_ZERO) are required for page tables on any given >> architecture. This creates a new generic GFP flag flag which can be used >> for any page table page allocation. Does not cause any functional change. > > I agree that some unification is due but GFP_PGTABLE is not something to > expose in generic gfp.h IMHO. It just risks an abuse. I would be looking
Why would you think that it risks an abuse ? It does not create new semantics of allocation in the buddy. Its just uses existing GFP_KERNEL allocation which is then getting zeroed out. The risks (if any) is exactly same as GFP_KERNEL.
> at providing asm-generic implementation and reuse it to remove the code
Does that mean GFP_PGTABLE can be created but not in gfp.h but in some other memory related header file ?
> duplication. But I haven't tried that to know that it will work out due > to small/subtle differences between arches.
IIUC from the allocation perspective GFP_ACCOUNT is the only thing which gets added with GFP_PGTABLE for user page table for memcg accounting purpose. There does not seem to be any other differences unless I am missing something.
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