From: zhouxianrong <zhouxianrong@xxxxxxxxxx>
the purpose of this patch is that when a reading swap fault
happens on a clean swap cache page whose swap count is equal
to one, then try_to_free_swap could remove this page from
swap cache and mark this page dirty. so if later we reclaimed
this page then we could pageout this page due to this dirty.
so i want to allow this action only for writing swap fault.
i sampled the data of non-dirty anonymous pages which is no
need to pageout and total anonymous pages in shrink_page_list.
the results are:
non-dirty anonymous pages total anonymous pages
before 26343 635218
after 36907 634312
Signed-off-by: zhouxianrong <zhouxianrong@xxxxxxxxxx>
---
mm/memory.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/memory.c b/mm/memory.c
index a728bed..5a944fe 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2999,7 +2999,7 @@ int do_swap_page(struct vm_fault *vmf)
}
swap_free(entry);
- if (mem_cgroup_swap_full(page) ||
+ if (((vmf->flags & FAULT_FLAG_WRITE) && mem_cgroup_swap_full(page)) ||
(vma->vm_flags & VM_LOCKED) || PageMlocked(page))
try_to_free_swap(page);
unlock_page(page);
--
1.7.9.5
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