1 files changed, 71 insertions, 0 deletions
diff --git a/mm/pt_reclaim.c b/mm/pt_reclaim.c
new file mode 100644
index 000000000000..7e9455a18aae
--- /dev/null
+++ b/mm/pt_reclaim.c
@@ -0,0 +1,71 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/hugetlb.h>
+#include <asm-generic/tlb.h>
+#include <asm/pgalloc.h>
+
+#include "internal.h"
+
+bool reclaim_pt_is_enabled(unsigned long start, unsigned long end,
+			   struct zap_details *details)
+{
+	return details && details->reclaim_pt && (end - start >= PMD_SIZE);
+}
+
+bool try_get_and_clear_pmd(struct mm_struct *mm, pmd_t *pmd, pmd_t *pmdval)
+{
+	spinlock_t *pml = pmd_lockptr(mm, pmd);
+
+	if (!spin_trylock(pml))
+		return false;
+
+	*pmdval = pmdp_get_lockless(pmd);
+	pmd_clear(pmd);
+	spin_unlock(pml);
+
+	return true;
+}
+
+void free_pte(struct mm_struct *mm, unsigned long addr, struct mmu_gather *tlb,
+	      pmd_t pmdval)
+{
+	pte_free_tlb(tlb, pmd_pgtable(pmdval), addr);
+	mm_dec_nr_ptes(mm);
+}
+
+void try_to_free_pte(struct mm_struct *mm, pmd_t *pmd, unsigned long addr,
+		     struct mmu_gather *tlb)
+{
+	pmd_t pmdval;
+	spinlock_t *pml, *ptl = NULL;
+	pte_t *start_pte, *pte;
+	int i;
+
+	pml = pmd_lock(mm, pmd);
+	start_pte = pte_offset_map_rw_nolock(mm, pmd, addr, &pmdval, &ptl);
+	if (!start_pte)
+		goto out_ptl;
+	if (ptl != pml)
+		spin_lock_nested(ptl, SINGLE_DEPTH_NESTING);
+
+	/* Check if it is empty PTE page */
+	for (i = 0, pte = start_pte; i < PTRS_PER_PTE; i++, pte++) {
+		if (!pte_none(ptep_get(pte)))
+			goto out_ptl;
+	}
+	pte_unmap(start_pte);
+
+	pmd_clear(pmd);
+
+	if (ptl != pml)
+		spin_unlock(ptl);
+	spin_unlock(pml);
+
+	free_pte(mm, addr, tlb, pmdval);
+
+	return;
+out_ptl:
+	if (start_pte)
+		pte_unmap_unlock(start_pte, ptl);
+	if (ptl != pml)
+		spin_unlock(pml);
+}