On Mon, Nov 30, 2020 at 12:27:10PM +0100, Peter Zijlstra wrote:
> There's no point in having the identical routines for PTE/PMD have
> different names.
>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
> include/linux/pgtable.h | 7 +------
> mm/hmm.c | 2 +-
> mm/mapping_dirty_helpers.c | 2 +-
> mm/mprotect.c | 2 +-
> mm/userfaultfd.c | 2 +-
> 5 files changed, 5 insertions(+), 10 deletions(-)
>
> +++ b/include/linux/pgtable.h
> @@ -1244,11 +1244,6 @@ static inline int pud_trans_unstable(pud
> #endif
> }
>
> -static inline pmd_t pmd_read_atomic(pmd_t *pmdp)
> -{
> - return pmdp_get_lockless(pmdp);
> -}
> -
> #ifndef arch_needs_pgtable_deposit
> #define arch_needs_pgtable_deposit() (false)
> #endif
> @@ -1275,7 +1270,7 @@ static inline pmd_t pmd_read_atomic(pmd_
> */
> static inline int pmd_none_or_trans_huge_or_clear_bad(pmd_t *pmd)
> {
> - pmd_t pmdval = pmd_read_atomic(pmd);
> + pmd_t pmdval = pmdp_get_lockless(pmd);
> /*
> * The barrier will stabilize the pmdval in a register or on
> * the stack so that it will stop changing under the code.
> +++ b/mm/hmm.c
> @@ -356,7 +356,7 @@ static int hmm_vma_walk_pmd(pmd_t *pmdp,
> * huge or device mapping one and compute corresponding pfn
> * values.
> */
> - pmd = pmd_read_atomic(pmdp);
> + pmd = pmdp_get_lockless(pmdp);
> barrier();
> if (!pmd_devmap(pmd) && !pmd_trans_huge(pmd))
> goto again;
The pagewalk API doesn't call the functions with interrupts disabled,
doesn't this mean we hit this assertion?
+#if CONFIG_PGTABLE_LEVELS > 2
+static inline pmd_t pmdp_get_lockless(pmd_t *pmdp)
+{
+ pmd_t pmd;
+
+ lockdep_assert_irqs_disabled();
+
It is only holding the read side of the mmap_sem here
Jason
