On 02/09/2015 05:32 PM, Peter Zijlstra wrote:

On Mon, Feb 09, 2015 at 03:04:22PM +0530, Raghavendra K T wrote:

quoted

So we have 3 choices,
1. xadd
2. continue with current approach.
3. a read before unlock and also after that.

For the truly paranoid we have probe_kernel_address(), suppose the lock
was in module space and the module just got unloaded under us.

Thanks.. Good idea, How costly is it?
atleast we could do probe_kernel_address() and check the value of
slowpath flag if people as us to address invalid read problem.