[ofa-general] [PATCH 8 of 8] This patch adds a lock ordering rule to avoid a potential deadlock when

Andrea Arcangeli
2008-04-02T21:30:09Z

# Date 1207159059 -7200
# Node ID f3f119118b0abd9c4624263ef388dc7230d937fe
# Parent 31fc23193bd039cc595fba1ca149a9715f7d0fb2
This patch adds a lock ordering rule to avoid a potential deadlock when
multiple mmap_sems need to be locked.

Signed-off-by: Dean Nelson <dcn@sgi.com>

diff --git a/mm/filemap.c b/mm/filemap.c
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -79,6 +79,9 @@
*
* ->i_mutex (generic_file_buffered_write)
* ->mmap_sem (fault_in_pages_readable->do_page_fault)
+ *
+ * When taking multiple mmap_sems, one should lock the lowest-addressed
+ * one first proceeding on up to the highest-addressed one.
*
* ->i_mutex
* ->i_alloc_sem (various)