powerpc/64s/radix: Fix huge vmap false positive

pmd_huge() is defined to false when HUGETLB_PAGE is not configured, but
the vmap code still installs huge PMDs. This leads to false bad PMD
errors when vunmapping because it is not seen as a huge PTE, and the bad
PMD check catches it. The end result may not be much more serious than
some bad pmd warning messages, because the pmd_none_or_clear_bad() does
what we wanted and clears the huge PTE anyway.

Fix this by checking pmd_is_leaf(), which checks for a PTE regardless of
config options. The whole huge/large/leaf stuff is a tangled mess but
that's kernel-wide and not something we can improve much in arch/powerpc
code.

pmd_page(), pud_page(), etc., called by vmalloc_to_page() on huge vmaps
can similarly trigger a false VM_BUG_ON when CONFIG_HUGETLB_PAGE=n, so
those checks are adjusted. The checks were added by commit d6eacedd1f0e
("powerpc/book3s: Use config independent helpers for page table walk"),
while implementing a similar fix for other page table walking functions.

Fixes: d909f9109c30 ("powerpc/64s/radix: Enable HAVE_ARCH_HUGE_VMAP")
Cc: stable@vger.kernel.org # v5.3+
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211216103342.609192-1-npiggin@gmail.com

diff --git a/arch/powerpc/mm/book3s64/radix_pgtable.c b/arch/powerpc/mm/book3s64/radix_pgtable.c
index 3c4f0ebe5df8eaa47f47787956e2da349794570c..ca23f5d1883ac6c2c907b7681b6d1af653d2cfe8 100644 (file)
--- a/arch/powerpc/mm/book3s64/radix_pgtable.c
+++ b/arch/powerpc/mm/book3s64/radix_pgtable.c
@@ -1076,7 +1076,7 @@ int pud_set_huge(pud_t *pud, phys_addr_t addr, pgprot_t prot)
 
 int pud_clear_huge(pud_t *pud)
 {
-       if (pud_huge(*pud)) {
+       if (pud_is_leaf(*pud)) {
                pud_clear(pud);
                return 1;
        }
@@ -1123,7 +1123,7 @@ int pmd_set_huge(pmd_t *pmd, phys_addr_t addr, pgprot_t prot)
 
 int pmd_clear_huge(pmd_t *pmd)
 {
-       if (pmd_huge(*pmd)) {
+       if (pmd_is_leaf(*pmd)) {
                pmd_clear(pmd);
                return 1;
        }

diff --git a/arch/powerpc/mm/pgtable_64.c b/arch/powerpc/mm/pgtable_64.c
index 78c8cf01db5f902bc2727f65ac6aaa0c92f8d9f6..175aabf101e8787efdf6c23e8ab918e9b30cc765 100644 (file)
--- a/arch/powerpc/mm/pgtable_64.c
+++ b/arch/powerpc/mm/pgtable_64.c
@@ -102,7 +102,8 @@ EXPORT_SYMBOL(__pte_frag_size_shift);
 struct page *p4d_page(p4d_t p4d)
 {
        if (p4d_is_leaf(p4d)) {
-               VM_WARN_ON(!p4d_huge(p4d));
+               if (!IS_ENABLED(CONFIG_HAVE_ARCH_HUGE_VMAP))
+                       VM_WARN_ON(!p4d_huge(p4d));
                return pte_page(p4d_pte(p4d));
        }
        return virt_to_page(p4d_pgtable(p4d));
@@ -112,7 +113,8 @@ struct page *p4d_page(p4d_t p4d)
 struct page *pud_page(pud_t pud)
 {
        if (pud_is_leaf(pud)) {
-               VM_WARN_ON(!pud_huge(pud));
+               if (!IS_ENABLED(CONFIG_HAVE_ARCH_HUGE_VMAP))
+                       VM_WARN_ON(!pud_huge(pud));
                return pte_page(pud_pte(pud));
        }
        return virt_to_page(pud_pgtable(pud));
@@ -125,7 +127,13 @@ struct page *pud_page(pud_t pud)
 struct page *pmd_page(pmd_t pmd)
 {
        if (pmd_is_leaf(pmd)) {
-               VM_WARN_ON(!(pmd_large(pmd) || pmd_huge(pmd)));
+               /*
+                * vmalloc_to_page may be called on any vmap address (not only
+                * vmalloc), and it uses pmd_page() etc., when huge vmap is
+                * enabled so these checks can't be used.
+                */
+               if (!IS_ENABLED(CONFIG_HAVE_ARCH_HUGE_VMAP))
+                       VM_WARN_ON(!(pmd_large(pmd) || pmd_huge(pmd)));
                return pte_page(pmd_pte(pmd));
        }
        return virt_to_page(pmd_page_vaddr(pmd));