[PATCH v6 03/24] mm: Dont assume page-table invariance during faults
From: Laurent Dufour <hidden>
Date: 2018-01-12 17:26:36
Also in:
linuxppc-dev, 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 !CONFIG_SPF] Signed-off-by: Laurent Dufour <redacted> --- mm/memory.c | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/mm/memory.c b/mm/memory.c
index 8a80986fff48..259f621345b2 100644
--- a/mm/memory.c
+++ b/mm/memory.c@@ -2274,6 +2274,7 @@ int apply_to_page_range(struct mm_struct *mm, unsigned long addr, } EXPORT_SYMBOL_GPL(apply_to_page_range); +#ifndef CONFIG_SPF /* * handle_pte_fault chooses page fault handler according to an entry which was * read non-atomically. Before making any commitment, on those architectures
@@ -2297,6 +2298,7 @@ static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd, pte_unmap(page_table); return same; } +#endif /* CONFIG_SPF */ static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma) {
@@ -2884,11 +2886,13 @@ int do_swap_page(struct vm_fault *vmf) swapcache = page; } +#ifndef CONFIG_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
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