mm: rework swap handling of zap_pte_range

Clean the code up by merging the device private/exclusive swap entry
handling with the rest, then we merge the pte clear operation too.

struct* page is defined in multiple places in the function, move it
upward.

free_swap_and_cache() is only useful for !non_swap_entry() case, put it
into the condition.

No functional change intended.

Link: https://lkml.kernel.org/r/20220216094810.60572-5-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: "Kirill A . Shutemov" <kirill@shutemov.name>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/memory.c b/mm/memory.c
index 8d5ecd3..2dbb4ac 100644 (file)
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1361,6 +1361,8 @@ again:
        arch_enter_lazy_mmu_mode();
        do {
                pte_t ptent = *pte;
+               struct page *page;
+
                if (pte_none(ptent))
                        continue;
 
@@ -1368,8 +1370,6 @@ again:
                        break;
 
                if (pte_present(ptent)) {
-                       struct page *page;
-
                        page = vm_normal_page(vma, addr, ptent);
                        if (unlikely(!should_zap_page(details, page)))
                                continue;
@@ -1403,28 +1403,21 @@ again:
                entry = pte_to_swp_entry(ptent);
                if (is_device_private_entry(entry) ||
                    is_device_exclusive_entry(entry)) {
-                       struct page *page = pfn_swap_entry_to_page(entry);
-
+                       page = pfn_swap_entry_to_page(entry);
                        if (unlikely(!should_zap_page(details, page)))
                                continue;
-                       pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
                        rss[mm_counter(page)]--;
-
                        if (is_device_private_entry(entry))
                                page_remove_rmap(page, false);
-
                        put_page(page);
-                       continue;
-               }
-
-               if (!non_swap_entry(entry)) {
+               } else if (!non_swap_entry(entry)) {
                        /* Genuine swap entry, hence a private anon page */
                        if (!should_zap_cows(details))
                                continue;
                        rss[MM_SWAPENTS]--;
+                       if (unlikely(!free_swap_and_cache(entry)))
+                               print_bad_pte(vma, addr, ptent, NULL);
                } else if (is_migration_entry(entry)) {
-                       struct page *page;
-
                        page = pfn_swap_entry_to_page(entry);
                        if (!should_zap_page(details, page))
                                continue;
@@ -1436,8 +1429,6 @@ again:
                        /* We should have covered all the swap entry types */
                        WARN_ON_ONCE(1);
                }
-               if (unlikely(!free_swap_and_cache(entry)))
-                       print_bad_pte(vma, addr, ptent, NULL);
                pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
        } while (pte++, addr += PAGE_SIZE, addr != end);