[PATCH v4 01/20] mm: Dont assume page-table invariance during faults
From: Laurent Dufour <hidden>
Date: 2017-10-09 10:08:13
Also in:
linux-mm, lkml
Subsystem:
memory management, memory management - core, the rest · Maintainers:
Andrew Morton, David Hildenbrand, Linus Torvalds
From: Peter Zijlstra <peterz@infradead.org> One of the side effects of speculating on faults (without holding mmap_sem) is that we can race with free_pgtables() and therefore we cannot assume the page-tables will stick around. Remove the reliance on the pte pointer. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> [Remove only if !__HAVE_ARCH_CALL_SPF] Signed-off-by: Laurent Dufour <redacted> --- mm/memory.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/mm/memory.c b/mm/memory.c
index 6632c9b357c9..4e4fe233d066 100644
--- a/mm/memory.c
+++ b/mm/memory.c@@ -2287,6 +2287,7 @@ int apply_to_page_range(struct mm_struct *mm, unsigned long addr, } EXPORT_SYMBOL_GPL(apply_to_page_range); +#ifndef __HAVE_ARCH_CALL_SPF /* * handle_pte_fault chooses page fault handler according to an entry which was * read non-atomically. Before making any commitment, on those architectures
@@ -2296,7 +2297,7 @@ EXPORT_SYMBOL_GPL(apply_to_page_range); * and do_anonymous_page can safely check later on). */ static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd, - pte_t *page_table, pte_t orig_pte) + pte_t *page_table, pte_t orig_pte) { int same = 1; #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
@@ -2310,6 +2311,7 @@ static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd, pte_unmap(page_table); return same; } +#endif static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma) {
@@ -2871,11 +2873,14 @@ int do_swap_page(struct vm_fault *vmf) if (vma_readahead) page = swap_readahead_detect(vmf, &swap_ra); + +#ifndef __HAVE_ARCH_CALL_SPF if (!pte_unmap_same(vma->vm_mm, vmf->pmd, vmf->pte, vmf->orig_pte)) { if (page) put_page(page); goto out; } +#endif entry = pte_to_swp_entry(vmf->orig_pte); if (unlikely(non_swap_entry(entry))) {
--
2.7.4