[PATCH 2/8] mm: Use find_get_swap_page in memcontrol

Matthew Wilcox (Oracle)
2020-08-19T18:48:44Z

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>
---
mm/memcontrol.c | 25 ++-----------------------
1 file changed, 2 insertions(+), 23 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index b807952b4d43..4075f214a841 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -5539,35 +5539,14 @@ 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_swap_page(vma->vm_file->f_mapping,
+ linear_page_index(vma, addr));
}

/**
--
2.28.0