Re: [mm] e6e88712e4: stress-ng.tmpfs.ops_per_sec -69.7% regression

[Matthew Wilcox]

On Mon, Nov 02, 2020 at 01:21:39PM +0800, Rong Chen wrote:
> we compared the tmpfs.ops_per_sec: (363 / 103.02) between this commit and
> parent commit.

Thanks!  I see about a 50% hit on my system, and this patch restores the
performance.  Can you verify this works for you?

diff --git a/mm/madvise.c b/mm/madvise.c
index 9b065d412e5f..e602333f8c0d 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -225,7 +225,7 @@ static void force_shm_swapin_readahead(struct vm_area_struct *vma,
 		struct address_space *mapping)
 {
 	XA_STATE(xas, &mapping->i_pages, linear_page_index(vma, start));
-	pgoff_t end_index = end / PAGE_SIZE;
+	pgoff_t end_index = linear_page_index(vma, end + PAGE_SIZE - 1);
 	struct page *page;
 
 	rcu_read_lock();