From: Jason Gunthorpe <jgg@nvidia.com>
To: Tao Cui <cuitao@kylinos.cn>
Cc: leon@kernel.org, linux-rdma@vger.kernel.org
Subject: Re: [PATCH rdma-next v2] RDMA/cgroup: fix resource leak in DRIVER_FAILURE cleanup path
Date: Mon, 25 May 2026 12:47:00 -0300 [thread overview]
Message-ID: <20260525154700.GA2483194@nvidia.com> (raw)
In-Reply-To: <20260520115506.1782475-1-cuitao@kylinos.cn>
On Wed, May 20, 2026 at 07:55:06PM +0800, Tao Cui wrote:
> When a driver fails to destroy an RDMA object during ufile cleanup,
> the kernel retries and eventually falls back to the
> RDMA_REMOVE_DRIVER_FAILURE path. This path sets obj->object = NULL
> before calling uverbs_destroy_uobject(), which skips the destroy_hw
> callback. Since ib_rdmacg_uncharge() lives inside destroy_hw_idr_uobject(),
> the HCA_OBJECT cgroup charge is never released.
>
> Add an explicit ib_rdmacg_uncharge() call in the DRIVER_FAILURE path
> to prevent the resource counter leak. Restrict this to IDR uobjects
> (type_class == &uverbs_idr_class), since only IDR objects charge
> RDMACG_RESOURCE_HCA_OBJECT in alloc_begin_idr_uobject(). FD objects
> never charge this resource, so their cg_obj.cg remains NULL and must
> not be passed to ib_rdmacg_uncharge(), which would otherwise dereference
> a NULL pointer in rdmacg_uncharge_hierarchy().
>
> Suggested-by: Sashiko AI
> Link: https://sashiko.dev/#/patchset/20260518031541.1552942-1-cuitao%40kylinos.cn
> Signed-off-by: Tao Cui <cuitao@kylinos.cn>
>
> ---
> Changes in v2:
> - Add type_class check to restrict ib_rdmacg_uncharge() to IDR uobjects
> only, as suggested by Sashiko AI.
> ---
> drivers/infiniband/core/rdma_core.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/infiniband/core/rdma_core.c b/drivers/infiniband/core/rdma_core.c
> index 5018ec837056..4fa14f27b76f 100644
> --- a/drivers/infiniband/core/rdma_core.c
> +++ b/drivers/infiniband/core/rdma_core.c
> @@ -917,8 +917,12 @@ static int __uverbs_cleanup_ufile(struct ib_uverbs_file *ufile,
> * racing with a lookup_get.
> */
> WARN_ON(uverbs_try_lock_object(obj, UVERBS_LOOKUP_WRITE));
> - if (reason == RDMA_REMOVE_DRIVER_FAILURE)
> + if (reason == RDMA_REMOVE_DRIVER_FAILURE) {
> obj->object = NULL;
> + if (obj->uapi_object->type_class == &uverbs_idr_class)
> + ib_rdmacg_uncharge(&obj->cg_obj, ib_dev,
> + RDMACG_RESOURCE_HCA_OBJECT);
> + }
No, this is AI slop, the point of this flow is to try to keep the
kernel hobbling forward when it has experienced a critical
failure. The only way to get here includes a WARN_ON.
We don't need to do any more than the bare minimal to not crash -
which is only to clean the ufile->uobjects
Jason
next prev parent reply other threads:[~2026-05-25 15:47 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-20 11:55 [PATCH rdma-next v2] RDMA/cgroup: fix resource leak in DRIVER_FAILURE cleanup path Tao Cui
2026-05-25 15:47 ` Jason Gunthorpe [this message]
2026-05-26 6:59 ` Tao Cui
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