From 95156f0051cba60ec674bbaa5cf7dc74a74c5612 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Mon, 12 Jan 2009 13:02:11 +0100 Subject: [PATCH] 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" Signed-off-by: Peter Zijlstra Signed-off-by: Ingo Molnar --- mm/memory.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/mm/memory.c b/mm/memory.c index e009ce870859..c2d4c477e5bb 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3165,6 +3165,15 @@ void print_vma_addr(char *prefix, unsigned long ip) #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