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-rw-r--r--mm/madvise.c25
1 files changed, 24 insertions, 1 deletions
diff --git a/mm/madvise.c b/mm/madvise.c
index ed137fde4459..98e28e777ccb 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -270,6 +270,7 @@ static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr,
spinlock_t *ptl;
pte_t *orig_pte, *pte, ptent;
struct page *page;
+ int nr_swap = 0;
split_huge_pmd(vma, pmd, addr);
if (pmd_trans_unstable(pmd))
@@ -280,8 +281,24 @@ static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr,
for (; addr != end; pte++, addr += PAGE_SIZE) {
ptent = *pte;
- if (!pte_present(ptent))
+ if (pte_none(ptent))
continue;
+ /*
+ * If the pte has swp_entry, just clear page table to
+ * prevent swap-in which is more expensive rather than
+ * (page allocation + zeroing).
+ */
+ if (!pte_present(ptent)) {
+ swp_entry_t entry;
+
+ entry = pte_to_swp_entry(ptent);
+ if (non_swap_entry(entry))
+ continue;
+ nr_swap--;
+ free_swap_and_cache(entry);
+ pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
+ continue;
+ }
page = vm_normal_page(vma, addr, ptent);
if (!page)
@@ -355,6 +372,12 @@ static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr,
}
}
out:
+ if (nr_swap) {
+ if (current->mm == mm)
+ sync_mm_rss(mm);
+
+ add_mm_counter(mm, MM_SWAPENTS, nr_swap);
+ }
arch_leave_lazy_mmu_mode();
pte_unmap_unlock(orig_pte, ptl);
cond_resched();