From: Will Deacon Date: Tue, 26 May 2020 17:33:02 +0000 (+0100) Subject: sparc32: mm: Only call ctor()/dtor() functions for first and last user X-Git-Tag: v5.15~3656^2~3^2 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=1996d47a0db27a3071f1a6587123185ba98c4585;p=platform%2Fkernel%2Flinux-starfive.git sparc32: mm: Only call ctor()/dtor() functions for first and last user 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 Fixes: 8c8f3156dd40 ("sparc32: mm: Reduce allocation size for PMD and PTE tables") Signed-off-by: Will Deacon Signed-off-by: David S. Miller --- diff --git a/arch/sparc/mm/srmmu.c b/arch/sparc/mm/srmmu.c index 589370a21..116d19a 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); }