Commit c62b17a5 authored Nov 12, 2009 by Romit Dasgupta Committed by Jens Axboe Nov 12, 2009

Thaw refrigerated bdi flusher threads before invoking kthread_stop on them



Unfreezes the bdi flusher task when the said task needs to exit.

Steps to reproduce this.
1) Mount a file system from MMC/SD card.
2) Unmount the file system. This creates a flusher task.
3) Attempt suspend to RAM. System is unresponsive.

This is because the bdi flusher thread is already in the refrigerator and will
remain so until it is thawed. The MMC driver suspend routine call stack will
ultimately issue a 'kthread_stop' on the bdi flusher thread and will block
until the flusher thread is exited. Since the bdi flusher thread is in the
refrigerator it never cleans up until thawed.

Signed-off-by: Romit Dasgupta <romit@ti.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

parent aa021baa

mm/backing-dev.c

+6 −2

Original line number	Diff line number	Diff line
		@@ -604,11 +604,15 @@ static void bdi_wb_shutdown(struct backing_dev_info *bdi)

		/*
		* Finally, kill the kernel threads. We don't need to be RCU
		* safe anymore, since the bdi is gone from visibility.
		* safe anymore, since the bdi is gone from visibility. Force
		* unfreeze of the thread before calling kthread_stop(), otherwise
		* it would never exet if it is currently stuck in the refrigerator.
		*/
		list_for_each_entry(wb, &bdi->wb_list, list)
		list_for_each_entry(wb, &bdi->wb_list, list) {
		wb->task->flags &= ~PF_FROZEN;
		kthread_stop(wb->task);
		}
		}

		/*
		* This bdi is going away now, make sure that no super_blocks point to it

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