> The "nested" part of the name is a little misleading. The function
> helps the lockdep core distinguish between locks belonging to the same
> class. Normally this is be done so that you can nest the locks in the
> proper order, but that shouldn't stop you from using it here.
Oh good point. I'll test the patch below during the week (my powerbook
doesn't have lockdep and I don't have another machine here right now)
but I'm fairly confident it'll fix the issue. I'll submit it after
testing.
johannes
--- linux-2.6.orig/kernel/power/disk.c 2007-10-28 11:34:32.669337294 +0100
+++ linux-2.6/kernel/power/disk.c 2007-10-28 11:37:29.849294324 +0100
@@ -456,7 +456,17 @@ static int software_resume(void)
int error;
unsigned int flags;
- mutex_lock(&pm_mutex);
+ /*
+ * name_to_dev_t() below takes a sysfs buffer mutex when sysfs
+ * is configured into the kernel. Since the regular hibernate
+ * trigger path is via sysfs which takes a buffer mutex before
+ * calling hibernate functions (which take pm_mutex) this can
+ * cause lockdep to complain about a possible ABBA deadlock
+ * which cannot happen since we're in the boot code here and
+ * sysfs can't be invoked yet. Therefore, we use a subclass
+ * here to avoid lockdep complaining.
+ */
+ mutex_lock_nested(&pm_mutex, 1);
if (!swsusp_resume_device) {
if (!strlen(resume_file)) {
mutex_unlock(&pm_mutex);
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