Re: [PATCH v2] nvdimm/pmem: Release gendisk on probe failure

[Christophe JAILLET <christophe.jaillet@wanadoo.fr>]

Le 02/10/2026 à 03:40, Alison Schofield a écrit :
> On Fri, Sep 11, 2026 at 01:55:43PM +0530, Hemanth Selam wrote:
>> pmem_attach_disk() allocates the gendisk with blk_alloc_disk() and hands
>> it to devres only once device_add_disk() has succeeded.  Until that
>> point the probe path owns the disk itself, which is why every failure
>> after the allocation jumps to the out: label and puts it there.
>>
>> The devm_init_badblocks() failure returns directly instead, so the disk
>> allocated a few lines earlier is never released.  Nothing releases it
>> afterwards either: the devres action that would have done so has not
>> been registered yet, so unbinding the namespace or destroying it does
>> not reach the disk, and it stays allocated along with its queue and its
>> bdev inode until the machine is rebooted.
>>
>> devm_init_badblocks() only fails when a single page allocation fails, so
>> reaching this at all needs memory exhaustion during namespace probe, and
>> because device_add_disk() has not run there is nothing user visible left
>> behind: no device node, no sysfs entry, only the leaked memory.
>>
>> Release the gendisk through the existing cleanup path on this failure.
>>
>> Fixes: 3dd60fb9d95d ("nvdimm/pmem: stop using q_usage_count as external pgmap refcount")
>> Signed-off-by: Hemanth Selam <hemanth.selam@gmail.com>
> 
> 
> Applied to libnvdimm-for-next:
> https://git.kernel.org/nvdimm/nvdimm/c/855a46681e0b

Hi,

For the records and if it sounds better patch, see [1] which propagates 
the error code from devm_init_badblocks() instead of hard-coding a -ENOMEM;

CJ

[1]: 
https://lore.kernel.org/lkml/f1933a01d9cefe24970ee93d741babb8fe9c1b32.1636219557.git.christophe.jaillet@wanadoo.fr/