lockdep, mm: fix might_fault() annotation
Some code (nfs/sunrpc) uses socket ops on kernel memory while holding
the mmap_sem, this is safe because kernel memory doesn't get paged out,
therefore we'll never actually fault, and the might_fault() annotations
will generate false positives.
Reported-by: "J. Bruce Fields" <bfields@fieldses.org>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/mm/memory.c b/mm/memory.c
index e009ce8..c2d4c47 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3165,6 +3165,15 @@
#ifdef CONFIG_PROVE_LOCKING
void might_fault(void)
{
+ /*
+ * Some code (nfs/sunrpc) uses socket ops on kernel memory while
+ * holding the mmap_sem, this is safe because kernel memory doesn't
+ * get paged out, therefore we'll never actually fault, and the
+ * below annotations will generate false positives.
+ */
+ if (segment_eq(get_fs(), KERNEL_DS))
+ return;
+
might_sleep();
/*
* it would be nicer only to annotate paths which are not under