Tue, Jul 14, 2026 at 04:28:01AM +0200, cui.tao@linux.dev wrote:

在 2026/7/13 17:34, Jiri Pirko 写道:

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Thu, Jul 09, 2026 at 03:04:23PM +0200, mkoutny@suse.com wrote:

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Hi.

On Thu, Jul 09, 2026 at 11:55:27AM +0200, Jiri Pirko [off-list ref] wrote:

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index 993446ab66d0..4523c1884d67 100644

--- a/Documentation/admin-guide/cgroup-v2.rst
+++ b/Documentation/admin-guide/cgroup-v2.rst

@@ -2752,6 +2752,13 @@ RDMA
 The "rdma" controller regulates the distribution and accounting of
 RDMA resources.
 
+When RDMA devices are isolated per network namespace (exclusive mode),
+device names are unique only within a network namespace. The device lines
+below are therefore scoped to the reading or writing process's network
+namespace: only devices accessible from that namespace are listed, and a
+limit is applied to the device of that name in that namespace. Configure
+limits from the same network namespace as the workloads.

OK.

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--- a/include/linux/cgroup_rdma.h
+++ b/include/linux/cgroup_rdma.h

@@ -7,6 +7,7 @@
 #define _CGROUP_RDMA_H
 
 #include <linux/cgroup.h>
+#include <net/net_namespace.h>
 
 enum rdmacg_resource_type {
 	RDMACG_RESOURCE_HCA_HANDLE,

@@ -34,6 +35,15 @@ struct rdmacg_device {
 	struct list_head	dev_node;
 	struct list_head	rpools;
 	char			*name;
+	/*
+	 * Net namespace the device belongs to. @netns_shared mirrors
+	 * ib_devices_shared_netns: when true the device is visible from every
+	 * net namespace (shared mode); otherwise @net is the only namespace
+	 * that may see and configure it. @netns_shared is updated when the
+	 * sharing mode changes, so use {READ,WRITE}_ONCE() to access it.
+	 */
+	possible_net_t		net;
+	bool			netns_shared;

Any reason to store the netns_shared split per device? (IIUC, it's a
global parameter.)

No reason, changed.

Hi Jiri,

A question on the v2 you mentioned to Michal.

Once netns_shared stops being cached per rdmacg_device,
rdmacg_device_visible() in kernel/cgroup/rdma.c still needs the current
sharing mode, whose authoritative value lives in the IB core
(ib_devices_shared_netns). How do you plan to expose it there without
the generic cgroup controller reaching back into drivers/infiniband/?
Exporting the global, or keeping an IB-side update hook, both feel a bit
awkward; it would be good to see which direction you took.

Exposing this from ib side is not doable, as IB may be compiled as a
module. So what I do is I intrododuce "static bool rdmacg_netns_shared"
in cgroup/rdma.c and exported function rdmacg_set_netns_shared() to set
it from IB.

On the mechanism itself: it's the right call that rdmacg_try_charge()
stays out of the scoping. Charging takes the rdmacg_device pointer
directly (no name lookup), and a task can only charge a device it
already holds a handle to, so applying visibility there would be wrong.
The scoping deliberately touches only the name-based lookup (the write
path) and the enumeration (read/show) paths -- worth keeping that
invariant in mind so a later patch doesn't grow the filter.

Thanks,
Tao> Thanks!

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Thanks,
Michal