mm: use find_get_incore_page in memcontrol

The current code does not protect against swapoff of the underlying
swap device, so this is a bug fix as well as a worthwhile reduction in
code complexity.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: William Kucharski <william.kucharski@oracle.com>
Link: https://lkml.kernel.org/r/20200910183318.20139-3-willy@infradead.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 5c1983c..d8bdbe1 100644 (file)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -5539,35 +5539,15 @@ static struct page *mc_handle_swap_pte(struct vm_area_struct *vma,
 static struct page *mc_handle_file_pte(struct vm_area_struct *vma,
                        unsigned long addr, pte_t ptent, swp_entry_t *entry)
 {
-       struct page *page = NULL;
-       struct address_space *mapping;
-       pgoff_t pgoff;
-
        if (!vma->vm_file) /* anonymous vma */
                return NULL;
        if (!(mc.flags & MOVE_FILE))
                return NULL;
 
-       mapping = vma->vm_file->f_mapping;
-       pgoff = linear_page_index(vma, addr);
-
        /* page is moved even if it's not RSS of this task(page-faulted). */
-#ifdef CONFIG_SWAP
        /* shmem/tmpfs may report page out on swap: account for that too. */
-       if (shmem_mapping(mapping)) {
-               page = find_get_entry(mapping, pgoff);
-               if (xa_is_value(page)) {
-                       swp_entry_t swp = radix_to_swp_entry(page);
-                       *entry = swp;
-                       page = find_get_page(swap_address_space(swp),
-                                            swp_offset(swp));
-               }
-       } else
-               page = find_get_page(mapping, pgoff);
-#else
-       page = find_get_page(mapping, pgoff);
-#endif
-       return page;
+       return find_get_incore_page(vma->vm_file->f_mapping,
+                       linear_page_index(vma, addr));
 }
 
 /**