Merge tag 'io_uring-7.3-20261002' of git://git.kernel.org/pub/scm/linux/kernel/git/axboe/linuxgrafted

Pull io_uring fixes from Jens Axboe:

 - Fix a task_work add use-after-free with SQPOLL.

   The sqpoll thread could pop and complete the last request while
   io_req_normal_work_add() was still looking at them after the mpscq
   push.

   Use the same approach as DEFER_TASKRUN to protect from that, holding
   an RCU read lock across the add, and have exit wait for an RCU grace
   period for SQPOLL rings as well.

 - CQE32 ring fixes: correct the free entry check for 32b CQEs, zero the
   big_cqe for aux CQEs, and only post the dummy skip CQE on CQE_MIXED
   rings

 - Mark the source filter table as COW when cloning bpf filters, so
   registering another filter on the source doesn't modify the shared
   table in place

 - Initialize the task context before running the BPF loop

 - Requeue zcrx multishot receives stopped by a local resource

 - End a TX_TIMESTAMP multishot cmd when the CQ is full (lollipopkit)

* tag 'io_uring-7.3-20261002' of git://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux:
  io_uring: fix task_work add use-after-free with SQPOLL
  io_uring/cmd_net: end TX_TIMESTAMP multishot when the CQ is full
  io_uring/zcrx: requeue multishot receives stopped by a local resource
  io_uring: initialize task context before running the BPF loop
  io_uring: zero big_cqe for aux CQEs on CQE32 rings
  io_uring: fix free entry check for 32b CQEs on CQE32 rings
  io_uring: only post the dummy skip CQE on CQE_MIXED rings
  io_uring/bpf_filter: mark source as COW when cloning filters

1 files changed, 18 insertions, 0 deletions

diff --git a/Documentation/admin-guide/namespaces/resource-control.rst b/Documentation/admin-guide/namespaces/resource-control.rst
new file mode 100644
index 000000000..553a44803
--- /dev/null
+++ b/Documentation/admin-guide/namespaces/resource-control.rst
@@ -0,0 +1,18 @@
+====================================
+User namespaces and resource control
+====================================
+
+The kernel contains many kinds of objects that either don't have
+individual limits or that have limits which are ineffective when
+a set of processes is allowed to switch their UID. On a system
+where the admins don't trust their users or their users' programs,
+user namespaces expose the system to potential misuse of resources.
+
+In order to mitigate this, we recommend that admins enable memory
+control groups on any system that enables user namespaces.
+Furthermore, we recommend that admins configure the memory control
+groups to limit the maximum memory usable by any untrusted user.
+
+Memory control groups can be configured by installing the libcgroup
+package present on most distros editing /etc/cgrules.conf,
+/etc/cgconfig.conf and setting up libpam-cgroup.