> On Jun 3, 2023, at 5:33 AM, Ido Schimmel <idosch@xxxxxxxxxx> wrote:
>
> On Sat, Jun 03, 2023 at 07:28:28AM +1000, NeilBrown wrote:
>> From: NeilBrown <neilb@xxxxxxx>
>> Date: Sat, 3 Jun 2023 07:14:14 +1000
>> Subject: [PATCH] lockd: drop inappropriate svc_get() from locked_get()
>>
>> The below-mentioned patch was intended to simplify refcounting on the
>> svc_serv used by locked. The goal was to only ever have a single
>> reference from the single thread. To that end we dropped a call to
>> lockd_start_svc() (except when creating thread) which would take a
>> reference, and dropped the svc_put(serv) that would drop that reference.
>>
>> Unfortunately we didn't also remove the svc_get() from
>> lockd_create_svc() in the case where the svc_serv already existed.
>> So after the patch:
>> - on the first call the svc_serv was allocated and the one reference
>> was given to the thread, so there are no extra references
>> - on subsequent calls svc_get() was called so there is now an extra
>> reference.
>> This is clearly not consistent.
>>
>> The inconsistency is also clear in the current code in lockd_get()
>> takes *two* references, one on nlmsvc_serv and one by incrementing
>> nlmsvc_users. This clearly does not match lockd_put().
>>
>> So: drop that svc_get() from lockd_get() (which used to be in
>> lockd_create_svc().
>>
>> Reported-by: Ido Schimmel <idosch@xxxxxxxxxx>
>> Fixes: b73a2972041b ("lockd: move lockd_start_svc() call into lockd_create_svc()")
>> Signed-off-by: NeilBrown <neilb@xxxxxxx>
>
> Thanks for the quick fix. I no longer see the memory leak with this
> patch.
>
> Tested-by: Ido Schimmel <idosch@xxxxxxxxxx>
Since we are getting close to the merge window, I've applied this
fix to nfsd-next.
--
Chuck Lever
