[PATCH] mm/uffd: Fix warning without PTE_MARKER_UFFD_WP compiled in

[Peter Xu]

When PTE_MARKER_UFFD_WP not configured, it's still possible to reach pte
marker code and trigger an warning. Add a few CONFIG_PTE_MARKER_UFFD_WP
ifdefs to make sure the code won't be reached when not compiled in.

Reported-by: syzbot+2b9b4f0895be09a6dec3@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Peter Xu <peterx@xxxxxxxxxx>
---
 mm/hugetlb.c  | 4 ++++
 mm/memory.c   | 2 ++
 mm/mprotect.c | 2 ++
 3 files changed, 8 insertions(+)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 0bdfc7e1c933..dd29cba46e9e 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -5059,6 +5059,7 @@ static void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct
 		 * unmapped and its refcount is dropped, so just clear pte here.
 		 */
 		if (unlikely(!pte_present(pte))) {
+#ifdef CONFIG_PTE_MARKER_UFFD_WP
 			/*
 			 * If the pte was wr-protected by uffd-wp in any of the
 			 * swap forms, meanwhile the caller does not want to
@@ -5070,6 +5071,7 @@ static void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct
 				set_huge_pte_at(mm, address, ptep,
 						make_pte_marker(PTE_MARKER_UFFD_WP));
 			else
+#endif
 				huge_pte_clear(mm, address, ptep, sz);
 			spin_unlock(ptl);
 			continue;
@@ -5098,11 +5100,13 @@ static void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct
 		tlb_remove_huge_tlb_entry(h, tlb, ptep, address);
 		if (huge_pte_dirty(pte))
 			set_page_dirty(page);
+#ifdef CONFIG_PTE_MARKER_UFFD_WP
 		/* Leave a uffd-wp pte marker if needed */
 		if (huge_pte_uffd_wp(pte) &&
 		    !(zap_flags & ZAP_FLAG_DROP_MARKER))
 			set_huge_pte_at(mm, address, ptep,
 					make_pte_marker(PTE_MARKER_UFFD_WP));
+#endif
 		hugetlb_count_sub(pages_per_huge_page(h), mm);
 		page_remove_rmap(page, vma, true);
 
diff --git a/mm/memory.c b/mm/memory.c
index a78814413ac0..de0dbe09b013 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1393,10 +1393,12 @@ zap_install_uffd_wp_if_needed(struct vm_area_struct *vma,
 			      unsigned long addr, pte_t *pte,
 			      struct zap_details *details, pte_t pteval)
 {
+#ifdef CONFIG_PTE_MARKER_UFFD_WP
 	if (zap_drop_file_uffd_wp(details))
 		return;
 
 	pte_install_uffd_wp_if_needed(vma, addr, pte, pteval);
+#endif
 }
 
 static unsigned long zap_pte_range(struct mmu_gather *tlb,
diff --git a/mm/mprotect.c b/mm/mprotect.c
index bc6bddd156ca..51e7dbd26b6a 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -260,6 +260,7 @@ static unsigned long change_pte_range(struct mmu_gather *tlb,
 		} else {
 			/* It must be an none page, or what else?.. */
 			WARN_ON_ONCE(!pte_none(oldpte));
+#ifdef CONFIG_PTE_MARKER_UFFD_WP
 			if (unlikely(uffd_wp && !vma_is_anonymous(vma))) {
 				/*
 				 * For file-backed mem, we need to be able to
@@ -271,6 +272,7 @@ static unsigned long change_pte_range(struct mmu_gather *tlb,
 					   make_pte_marker(PTE_MARKER_UFFD_WP));
 				pages++;
 			}
+#endif
 		}
 	} while (pte++, addr += PAGE_SIZE, addr != end);
 	arch_leave_lazy_mmu_mode();
-- 
2.37.3


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