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Diffstat (limited to 'mm/mapping_dirty_helpers.c')
-rw-r--r--mm/mapping_dirty_helpers.c42
1 files changed, 38 insertions, 4 deletions
diff --git a/mm/mapping_dirty_helpers.c b/mm/mapping_dirty_helpers.c
index 71070dda9643..2c7d03675903 100644
--- a/mm/mapping_dirty_helpers.c
+++ b/mm/mapping_dirty_helpers.c
@@ -111,26 +111,60 @@ static int clean_record_pte(pte_t *pte, unsigned long addr,
return 0;
}
-/* wp_clean_pmd_entry - The pagewalk pmd callback. */
+/*
+ * wp_clean_pmd_entry - The pagewalk pmd callback.
+ *
+ * Dirty-tracking should take place on the PTE level, so
+ * WARN() if encountering a dirty huge pmd.
+ * Furthermore, never split huge pmds, since that currently
+ * causes dirty info loss. The pagefault handler should do
+ * that if needed.
+ */
static int wp_clean_pmd_entry(pmd_t *pmd, unsigned long addr, unsigned long end,
struct mm_walk *walk)
{
- /* Dirty-tracking should be handled on the pte level */
pmd_t pmdval = pmd_read_atomic(pmd);
+ if (!pmd_trans_unstable(&pmdval))
+ return 0;
+
+ if (pmd_none(pmdval)) {
+ walk->action = ACTION_AGAIN;
+ return 0;
+ }
+
+ /* Huge pmd, present or migrated */
+ walk->action = ACTION_CONTINUE;
if (pmd_trans_huge(pmdval) || pmd_devmap(pmdval))
WARN_ON(pmd_write(pmdval) || pmd_dirty(pmdval));
return 0;
}
-/* wp_clean_pud_entry - The pagewalk pud callback. */
+/*
+ * wp_clean_pud_entry - The pagewalk pud callback.
+ *
+ * Dirty-tracking should take place on the PTE level, so
+ * WARN() if encountering a dirty huge puds.
+ * Furthermore, never split huge puds, since that currently
+ * causes dirty info loss. The pagefault handler should do
+ * that if needed.
+ */
static int wp_clean_pud_entry(pud_t *pud, unsigned long addr, unsigned long end,
struct mm_walk *walk)
{
- /* Dirty-tracking should be handled on the pte level */
pud_t pudval = READ_ONCE(*pud);
+ if (!pud_trans_unstable(&pudval))
+ return 0;
+
+ if (pud_none(pudval)) {
+ walk->action = ACTION_AGAIN;
+ return 0;
+ }
+
+ /* Huge pud */
+ walk->action = ACTION_CONTINUE;
if (pud_trans_huge(pudval) || pud_devmap(pudval))
WARN_ON(pud_write(pudval) || pud_dirty(pudval));