On Wed, Jan 29, 2020 at 12:11:50PM +0000, Will Deacon wrote:
On Wed, Jan 29, 2020 at 11:39:44AM +0100, Peter Zijlstra wrote:
--- a/arch/m68k/include/asm/motorola_pgalloc.h +++ b/arch/m68k/include/asm/motorola_pgalloc.h @@ -10,60 +10,28 @@ extern int free_pointer_table(pmd_t *); static inline pte_t *pte_alloc_one_kernel(struct mm_struct *mm) { - pte_t *pte; - - pte = (pte_t *)__get_free_page(GFP_KERNEL|__GFP_ZERO); - if (pte) { - __flush_page_to_ram(pte); - flush_tlb_kernel_page(pte); - nocache_page(pte); - } - - return pte; + return (pte_t *)get_pointer_table();Weirdly, get_pointer_table() seems to elide the __flush_page_to_ram() call, so you're missing that for ptes with this change. I think it's probably needed for the higher levels too (and kernel_page_table() does it for example) so I'd be inclined to add it unconditionally rather than predicate it on the allocation type introduced by your later patch.
The next patch adds that unconditionally to the table allocator. The only thing conditional on the type is the PG_PageTable and NR_PAGETABLES accounting crud.
--- a/arch/m68k/include/asm/page.h +++ b/arch/m68k/include/asm/page.h @@ -30,7 +30,7 @@ typedef struct { unsigned long pmd; } pm typedef struct { unsigned long pte; } pte_t; typedef struct { unsigned long pgd; } pgd_t; typedef struct { unsigned long pgprot; } pgprot_t; -typedef struct page *pgtable_t; +typedef pte_t *pgtable_t;Urgh, this is a big (cross-arch) mess that we should fix later.
Yes, I ran into this when I did those MMU-gather fixes as well. For this patch I cribbed what s390 already does.
