[PATCH 4/8] proc: Optimise smaps for shmem entries

Matthew Wilcox (Oracle)
2020-08-19T18:48:46Z

Avoid bumping the refcount on pages when we're only interested in the
swap entries.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
fs/proc/task_mmu.c | 8 +-------
1 file changed, 1 insertion(+), 7 deletions(-)

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 5066b0251ed8..e42d9e5e9a3c 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -520,16 +520,10 @@ static void smaps_pte_entry(pte_t *pte, unsigned long addr,
page = device_private_entry_to_page(swpent);
} else if (unlikely(IS_ENABLED(CONFIG_SHMEM) && mss->check_shmem_swap
&& pte_none(*pte))) {
- page = find_get_entry(vma->vm_file->f_mapping,
+ page = xa_load(&vma->vm_file->f_mapping->i_pages,
linear_page_index(vma, addr));
- if (!page)
- return;
-
if (xa_is_value(page))
mss->swap += PAGE_SIZE;
- else
- put_page(page);
-
return;
}

--
2.28.0