On Tue, Mar 18, 2014 at 11:39 PM, Xuelin Shi [off-list ref] wrote:

Hi Dan,

In async_mult(...) of async_raid6_recov.c, the count 3 is used to request an unmap.
However the to_cnt and bidi_cnt are both set to 1 and from_cnt to 0.
Then while trying to do unmap, we are getting the wrong "unmap" from a different mempool.

In this patch, the mempool is associated with the unmap structure instead of computing it again.
By this way, it is guaranteed that the unmap is the same when we get and put the unmap data.

BTW: the mempool is just used to manage the struct unmap, not the pages.

I see, what about just storing the map_cnt at allocation time?  It
could be another byte in struct dmaengine_unmap_data rather than an 8
byte pointer.