The SRMMU page-table allocator allocates multiple PTE tables per page,
since they are only 1K in size. However, this means that calls to
pgtable_pte_page_{ctor,dtor}() must be serialised and performed only by
the first and last page-table allocation for the page respectively.Use the page reference count to track how many PTE tables we have allocated for a given page returned by the SRMMU allocator and only call the ctor()/dtor() functions for the first and last user respectively. Cc: David S. Miller <[email protected]> Fixes: 8c8f3156dd40 ("sparc32: mm: Reduce allocation size for PMD and PTE tables") Signed-off-by: Will Deacon <[email protected]> --- arch/sparc/mm/srmmu.c | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-) diff --git a/arch/sparc/mm/srmmu.c b/arch/sparc/mm/srmmu.c index 589370a21b12..116d19a390f2 100644 --- a/arch/sparc/mm/srmmu.c +++ b/arch/sparc/mm/srmmu.c @@ -364,9 +364,13 @@ pgtable_t pte_alloc_one(struct mm_struct *mm) if ((ptep = pte_alloc_one_kernel(mm)) == 0) return NULL; page = pfn_to_page(__nocache_pa((unsigned long)ptep) >> PAGE_SHIFT); - if (!pgtable_pte_page_ctor(page)) { - return NULL; + spin_lock(&mm->page_table_lock); + if (page_ref_inc_return(page) == 2 && !pgtable_pte_page_ctor(page)) { + page_ref_dec(page); + ptep = NULL; } + spin_unlock(&mm->page_table_lock); + return ptep; } @@ -375,7 +379,11 @@ void pte_free(struct mm_struct *mm, pgtable_t ptep) struct page *page; page = pfn_to_page(__nocache_pa((unsigned long)ptep) >> PAGE_SHIFT); - pgtable_pte_page_dtor(page); + spin_lock(&mm->page_table_lock); + if (page_ref_dec_return(page) == 1) + pgtable_pte_page_dtor(page); + spin_unlock(&mm->page_table_lock); + srmmu_free_nocache(ptep, SRMMU_PTE_TABLE_SIZE); } -- 2.27.0.rc0.183.gde8f92d652-goog
