On 22/05/18 10:56 AM, Dan Williams wrote:
On Tue, May 22, 2018 at 9:42 AM, Logan Gunthorpe logang@deltatee.com wrote:
Hey Dan,
On 21/05/18 06:07 PM, Dan Williams wrote:
Without this change we could fail to register the teardown of devm_memremap_pages(). The likelihood of hitting this failure is tiny as small memory allocations almost always succeed. However, the impact of the failure is large given any future reconfiguration, or disable/enable, of an nvdimm namespace will fail forever as subsequent calls to devm_memremap_pages() will fail to setup the pgmap_radix since there will be stale entries for the physical address range.
Sorry, I don't follow this. The change only seems to prevent a warning from occurring in this situation. Won't pgmap_radix_release() still be called regardless of whether this patch is applied?
devm_add_action() does not call the release function, devm_add_action_or_reset() does.
Oh, yes. Thanks I see that now.
Ah, true, good catch!
We should manually kill in the !registered case. I think this means we need to pass in the custom kill routine, because for the pmem driver it's blk_freeze_queue_start().
It may be cleaner to just have the caller call the specific kill function if devm_memremap_pages fails... Though, I don't fully understand how the nvdimm pmem driver cleans up the percpu counter.
Logan