The shared fault handler can also benefit from fault-around. While it
is uncommon to write to MAP_SHARED files, applications that do will see
a huge benefit with will-it-scale:page_fault3 (shared file write fault)
improving by 375%.
Signed-off-by: Yin Fengwei <fengwei.yin@xxxxxxxxx>
Reviewed-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
---
mm/memory.c | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/mm/memory.c b/mm/memory.c
index 7a04a1130ec1..51c04bb60724 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -4546,6 +4546,17 @@ static vm_fault_t do_shared_fault(struct vm_fault *vmf)
struct vm_area_struct *vma = vmf->vma;
vm_fault_t ret, tmp;
+ /*
+ * Let's call ->map_pages() first and use ->fault() as fallback
+ * if page by the offset is not ready to be mapped (cold cache or
+ * something).
+ */
+ if (should_fault_around(vmf)) {
+ ret = do_fault_around(vmf);
+ if (ret)
+ return ret;
+ }
+
ret = __do_fault(vmf);
if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
return ret;
--
2.30.2
