module: Annotate nested sleep in resolve_symbol()

Because wait_event() loops are safe vs spurious wakeups we can allow the
occasional sleep -- which ends up being very similar.

Reported-by: Dave Jones <davej@codemonkey.org.uk>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Dave Jones <davej@codemonkey.org.uk>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

1 files changed, 6 insertions, 0 deletions

diff --git a/kernel/module.c b/kernel/module.c
index 2461370813b3..d7a92682fba3 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -1225,6 +1225,12 @@ static const struct kernel_symbol *resolve_symbol(struct module *mod,
         const unsigned long *crc;
         int err;
 
+        /*
+         * The module_mutex should not be a heavily contended lock;
+         * if we get the occasional sleep here, we'll go an extra iteration
+         * in the wait_event_interruptible(), which is harmless.
+         */
+        sched_annotate_sleep();
         mutex_lock(&module_mutex);
         sym = find_symbol(name, &owner, &crc,
                           !(mod->taints & (1 << TAINT_PROPRIETARY_MODULE)), true);