[PATCH v2 07/32] mm/page_vma_mapped: reformat map_pte() with less indentation

Hugh Dickins
2023-06-09T01:14:24Z

No functional change here, but adjust the format of map_pte() so that the
following commit will be easier to read: separate out the PVMW_SYNC case
first, and remove two levels of indentation from the ZONE_DEVICE case.

Signed-off-by: Hugh Dickins <hughd@google.com>
---
mm/page_vma_mapped.c | 65 +++++++++++++++++++++++---------------------
1 file changed, 34 insertions(+), 31 deletions(-)

diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c
index 007dc7456f0e..947dc7491815 100644
--- a/mm/page_vma_mapped.c
+++ b/mm/page_vma_mapped.c
@@ -15,38 +15,41 @@ static inline bool not_found(struct page_vma_mapped_walk *pvmw)

static bool map_pte(struct page_vma_mapped_walk *pvmw)
{
- pvmw->pte = pte_offset_map(pvmw->pmd, pvmw->address);
- if (!(pvmw->flags & PVMW_SYNC)) {
- if (pvmw->flags & PVMW_MIGRATION) {
- if (!is_swap_pte(*pvmw->pte))
- return false;
- } else {
- /*
- * We get here when we are trying to unmap a private
- * device page from the process address space. Such
- * page is not CPU accessible and thus is mapped as
- * a special swap entry, nonetheless it still does
- * count as a valid regular mapping for the page (and
- * is accounted as such in page maps count).
- *
- * So handle this special case as if it was a normal
- * page mapping ie lock CPU page table and returns
- * true.
- *
- * For more details on device private memory see HMM
- * (include/linux/hmm.h or mm/hmm.c).
- */
- if (is_swap_pte(*pvmw->pte)) {
- swp_entry_t entry;
+ if (pvmw->flags & PVMW_SYNC) {
+ /* Use the stricter lookup */
+ pvmw->pte = pte_offset_map_lock(pvmw->vma->vm_mm, pvmw->pmd,
+ pvmw->address, &pvmw->ptl);
+ return true;
+ }

- /* Handle un-addressable ZONE_DEVICE memory */
- entry = pte_to_swp_entry(*pvmw->pte);
- if (!is_device_private_entry(entry) &&
- !is_device_exclusive_entry(entry))
- return false;
- } else if (!pte_present(*pvmw->pte))
- return false;
- }
+ pvmw->pte = pte_offset_map(pvmw->pmd, pvmw->address);
+ if (pvmw->flags & PVMW_MIGRATION) {
+ if (!is_swap_pte(*pvmw->pte))
+ return false;
+ } else if (is_swap_pte(*pvmw->pte)) {
+ swp_entry_t entry;
+ /*
+ * Handle un-addressable ZONE_DEVICE memory.
+ *
+ * We get here when we are trying to unmap a private
+ * device page from the process address space. Such
+ * page is not CPU accessible and thus is mapped as
+ * a special swap entry, nonetheless it still does
+ * count as a valid regular mapping for the page
+ * (and is accounted as such in page maps count).
+ *
+ * So handle this special case as if it was a normal
+ * page mapping ie lock CPU page table and return true.
+ *
+ * For more details on device private memory see HMM
+ * (include/linux/hmm.h or mm/hmm.c).
+ */
+ entry = pte_to_swp_entry(*pvmw->pte);
+ if (!is_device_private_entry(entry) &&
+ !is_device_exclusive_entry(entry))
+ return false;
+ } else if (!pte_present(*pvmw->pte)) {
+ return false;
}
pvmw->ptl = pte_lockptr(pvmw->vma->vm_mm, pvmw->pmd);
spin_lock(pvmw->ptl);
--
2.35.3