lkml.org 
[lkml]   [2018]   [Sep]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 2/2] s390/tlb: convert to generic mmu_gather
On Tue, Sep 18, 2018 at 02:51:51PM +0200, Martin Schwidefsky wrote:
> +#define pte_free_tlb pte_free_tlb
> +#define pmd_free_tlb pmd_free_tlb
> +#define p4d_free_tlb p4d_free_tlb
> +#define pud_free_tlb pud_free_tlb

> @@ -121,9 +62,18 @@ static inline void tlb_remove_page_size(struct mmu_gather *tlb,
> * page table from the tlb.
> */
> static inline void pte_free_tlb(struct mmu_gather *tlb, pgtable_t pte,
> + unsigned long address)
> {
> + __tlb_adjust_range(tlb, address, PAGE_SIZE);
> + tlb->mm->context.flush_mm = 1;
> + tlb->freed_tables = 1;
> + tlb->cleared_ptes = 1;
> + /*
> + * page_table_free_rcu takes care of the allocation bit masks
> + * of the 2K table fragments in the 4K page table page,
> + * then calls tlb_remove_table.
> + */
> + page_table_free_rcu(tlb, (unsigned long *) pte, address);

(whitespace damage, fixed)

Also, could you perhaps explain the need for that
page_table_alloc/page_table_free code? That is, I get the comment about
using 2K page-table fragments out of 4k physical page, but why this
custom allocator instead of kmem_cache? It feels like there's a little
extra complication, but it's not immediately obvious what.

> }

We _could_ use __pte_free_tlb() here I suppose, but...

> /*
> @@ -139,6 +89,10 @@ static inline void pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmd,
> if (tlb->mm->context.asce_limit <= _REGION3_SIZE)
> return;
> pgtable_pmd_page_dtor(virt_to_page(pmd));
> + __tlb_adjust_range(tlb, address, PAGE_SIZE);
> + tlb->mm->context.flush_mm = 1;
> + tlb->freed_tables = 1;
> + tlb->cleared_puds = 1;
> tlb_remove_table(tlb, pmd);
> }
>
> @@ -154,6 +108,10 @@ static inline void p4d_free_tlb(struct mmu_gather *tlb, p4d_t *p4d,
> {
> if (tlb->mm->context.asce_limit <= _REGION1_SIZE)
> return;
> + __tlb_adjust_range(tlb, address, PAGE_SIZE);
> + tlb->mm->context.flush_mm = 1;
> + tlb->freed_tables = 1;
> + tlb->cleared_p4ds = 1;
> tlb_remove_table(tlb, p4d);
> }
>
> @@ -169,19 +127,11 @@ static inline void pud_free_tlb(struct mmu_gather *tlb, pud_t *pud,
> {
> if (tlb->mm->context.asce_limit <= _REGION2_SIZE)
> return;
> + tlb->mm->context.flush_mm = 1;
> + tlb->freed_tables = 1;
> + tlb->cleared_puds = 1;
> tlb_remove_table(tlb, pud);
> }

It's that ASCE limit that makes it impossible to use the generic
helpers, right?


\
 
 \ /
  Last update: 2018-09-19 14:39    [W:0.070 / U:1.292 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site