The map_pages fs method should be safe to run under the VMA lock instead
of the mmap lock. This should have a measurable reduction in contention
on the mmap lock.
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
---
mm/memory.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/mm/memory.c b/mm/memory.c
index 9952bebd25b4..590ccaf6f7fb 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -4521,8 +4521,6 @@ static vm_fault_t do_read_fault(struct vm_fault *vmf)
{
vm_fault_t ret = 0;
- if (vmf->flags & FAULT_FLAG_VMA_LOCK)
- return VM_FAULT_RETRY;
/*
* 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
@@ -4534,6 +4532,8 @@ static vm_fault_t do_read_fault(struct vm_fault *vmf)
return ret;
}
+ if (vmf->flags & FAULT_FLAG_VMA_LOCK)
+ return VM_FAULT_RETRY;
ret = __do_fault(vmf);
if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
return ret;
--
2.39.2
