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authorWill Deacon <will@kernel.org>2020-05-26 18:33:02 +0100
committerDavid S. Miller <davem@davemloft.net>2020-06-02 18:45:51 -0700
commit1996d47a0db27a3071f1a6587123185ba98c4585 (patch)
tree3b849e4c43873e8fc1fead51e5531bcb2d0d2b19
parent60bccaa671bce7ed040d9511b0738ca3b0a0e9ff (diff)
downloadlinux-1996d47a0db27a3071f1a6587123185ba98c4585.tar.gz
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 <davem@davemloft.net> Fixes: 8c8f3156dd40 ("sparc32: mm: Reduce allocation size for PMD and PTE tables") Signed-off-by: Will Deacon <will@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--arch/sparc/mm/srmmu.c14
1 files 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);
}