On Mon, Mar 08, 2021 at 06:54:02PM +0000, Luck, Tony wrote:

quoted

quoted

So it should be safe to grab and hold a mutex.  See patch below.

The mutex approach looks simpler and safer, so I'm fine with it.

Thanks.  Is that an "Acked-by:"?

Not yet, I intended to add it after full patch is submitted
(with your Signed-off-by and commit log).

quoted

quoted

 /**
  * memory_failure - Handle memory failure of a page.
  * @pfn: Page Number of the corrupted page

@@ -1424,12 +1426,18 @@ int memory_failure(unsigned long pfn, int flags)
 		return -ENXIO;
 	}
 
+	mutex_lock(&mf_mutex);

Is it better to take mutex before memory_failure_dev_pagemap() block?
Or we don't have to protect against race for device memory?

No races (recovery is only attempted for errors in normal memory).

OK, thanks.

- Naoya