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Subject: Re: next-20090202: task kmemleak:763 blocked for more than 120
	seconds.
From: Catalin Marinas <catalin.marinas@arm.com>
To: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Mandeep Singh Baines <msb@google.com>,
       Alexander Beregalov <a.beregalov@gmail.com>,
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Date: Tue, 03 Feb 2009 12:48:34 +0000
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On Tue, 2009-02-03 at 01:41 +0100, Frederic Weisbecker wrote:
> Right. BTW, I wonder how it behaves in case of suspend to disk.
> But changing the state to TASK_INTERRUPTIBLE wouldn't change it in this case since the
> signals are only sent to userpace threads to freeze them.
> 
> Kernel threads try to freeze by themselves.
> 
> But for such very long schedule_timeout, will the hibernation wait for kmemleak
> to wake up and then try_to_freeze() before suspend to disk?

I haven't added anything to kmemleak for this. Does something like below
look feasible?

--- a/mm/kmemleak.c
+++ b/mm/kmemleak.c
@@ -88,6 +88,7 @@
 #include <linux/errno.h>
 #include <linux/uaccess.h>
 #include <linux/string.h>
+#include <linux/freezer.h>
 
 #include <asm/sections.h>
 #include <asm/processor.h>
@@ -1070,8 +1071,11 @@ static int kmemleak_scan_thread(void *arg)
 
 		mutex_unlock(&scan_mutex);
 		/* wait before the next scan */
-		while (timeout && !kthread_should_stop())
+		while (timeout && !kthread_should_stop()) {
+			if (try_to_freeze())
+				break;
 			timeout = schedule_timeout_interruptible(timeout);
+		}
 	}
 
 	pr_info("kmemleak: Automatic memory scanning thread ended\n");

Thanks.

-- 
Catalin