simple_lmk: Make the reclaim thread freezable

There are two problems with the current uninterruptible wait used in the
reclaim thread: the hung task detector is upset about an uninterruptible
thread being asleep for so long, and killing processes can generate I/O.

Since killing a process can generate I/O, the reclaim thread should
participate in system-wide suspend operations. This neatly solves the
hung task detector issue since wait_event_freezable() puts the current
process into an interruptible sleep.

Signed-off-by: Sultan Alsawaf <sultan@kerneltoast.com>

drivers/android/simple_lmk.c

@@ -5,6 +5,7 @@
 
 #define pr_fmt(fmt) "simple_lmk: " fmt
 
+#include <linux/freezer.h>
 #include <linux/kthread.h>
 #include <linux/mm.h>
 #include <linux/moduleparam.h>
@@ -270,9 +271,10 @@ static int simple_lmk_reclaim_thread(void *data)
 	};
 
 	sched_setscheduler_nocheck(current, SCHED_FIFO, &sched_max_rt_prio);
+	set_freezable();
 
 	while (1) {
-		wait_event(oom_waitq, atomic_read(&needs_reclaim));
+		wait_event_freezable(oom_waitq, atomic_read(&needs_reclaim));
 		scan_and_kill();
 		atomic_set_release(&needs_reclaim, 0);
 	}