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? But it looks to me like this patch doesn't quite solve the issue -- at least when looking at dax/pmem.c: If devm_add_action_or_reset() fails, then dax_pmem_percpu_kill() won't be registered as an action and the percpu_ref will never get killed. Thus, dax_pmem_percpu_release() would not get called and dax_pmem_percpu_exit() will hang waiting for a completion that will never occur. So we probably need to add a kill call somewhere on the failing path... Logan
