Merge tag 'cgroup-for-7.2-rc3-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

Pull cgroup fixes from Tejun Heo:

 - A cpuset that never set its memory nodes could divide by zero when a
   task's mempolicy rebinds on CPU hotplug. Rebind against the effective
   nodes, which are always populated

 - Documentation fixes for memory.stat, io.stat, and the misc and v1
   RDMA controllers

* tag 'cgroup-for-7.2-rc3-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  Docs/admin-guide/cgroup-v2: note blkcg_debug_stats gates io.latency stats
  Docs/admin-guide/cgroup-v1: document rdma.peak, rdma.events and rdma.events.local
  Docs/admin-guide/cgroup-v2: drop stale misc interface file count
  cgroup/cpuset: rebind mm mempolicy to effective_mems, not mems_allowed
  Docs/admin-guide/cgroup-v2: fix memory.stat doc details

Author: torvalds

Documentation/admin-guide/cgroup-v1/rdma.rst

@@ -9,6 +9,7 @@ RDMA Controller
      1-2. Why RDMA controller needed?
      1-3. How is RDMA controller implemented?
    2. Usage Examples
+   3. RDMA Interface Files
 
 1. Overview
 ===========
@@ -115,3 +116,68 @@ Following resources can be accounted by rdma controller.
 (d) Delete resource limit::
 
 	echo mlx4_0 hca_handle=max hca_object=max > /sys/fs/cgroup/rdma/1/rdma.max
+
+3. RDMA Interface Files
+========================
+
+The following interface files are available in each non-root RDMA cgroup.
+
+  rdma.max
+	A read-write file which describes the configured resource limit
+	for an RDMA/IB device.  See the Usage Examples above.
+
+  rdma.current
+	A read-only file which describes the current resource usage.
+
+  rdma.peak
+	A read-only nested-keyed file which shows the historical high
+	watermark of resource usage per device since the cgroup was created.
+
+	An example for mlx4 and ocrdma device follows::
+
+	  mlx4_0 hca_handle=1 hca_object=20
+	  ocrdma1 hca_handle=0 hca_object=23
+
+  rdma.events
+	A read-only nested-keyed file which exists on non-root cgroups
+	and contains the following keys:
+
+	  max
+		The number of times a process in this cgroup or its
+		descendants attempted an RDMA resource allocation that
+		was rejected because a rdma.max limit in the subtree
+		was reached.  This is a hierarchical counter propagated
+		upward to all ancestor cgroups.  A value change in this
+		file generates a file modified event.
+
+	  alloc_fail
+		The number of RDMA resource allocation attempts that
+		originated in this cgroup or its descendants and failed
+		due to a rdma.max limit being reached.  This is a
+		hierarchical counter propagated upward.
+
+	An example for mlx4 device follows::
+
+	  mlx4_0 hca_handle.max=5 hca_handle.alloc_fail=3 hca_object.max=0 hca_object.alloc_fail=0
+
+  rdma.events.local
+	Similar to rdma.events but the fields are local to the cgroup,
+	i.e. not hierarchical.  The file modified event generated on this
+	file reflects only the local events.
+
+	The following nested keys are defined.
+
+	  max
+		The number of times a process in this cgroup or its
+		descendants attempted an RDMA resource allocation that
+		was rejected because this cgroup's own rdma.max limit
+		was reached.
+
+	  alloc_fail
+		The number of RDMA resource allocation attempts
+		originating from this cgroup that failed due to this
+		cgroup's or an ancestor's rdma.max limit.
+
+	An example for mlx4 device follows::
+
+	  mlx4_0 hca_handle.max=5 hca_handle.alloc_fail=0 hca_object.max=0 hca_object.alloc_fail=0

Documentation/admin-guide/cgroup-v2.rst

@@ -1570,7 +1570,7 @@ The following nested keys are defined.
 	  sock (npn)
 		Amount of memory used in network transmission buffers
 
-	  vmalloc (npn)
+	  vmalloc
 		Amount of memory used for vmap backed memory.
 
 	  shmem
@@ -1735,7 +1735,7 @@ The following nested keys are defined.
 		Number of pages written from zswap to swap.
 
 	  zswap_incomp
-		Number of incompressible pages currently stored in zswap
+		Amount of memory used by incompressible pages currently stored in zswap
 		without compression. These pages could not be compressed to
 		a size smaller than PAGE_SIZE, so they are stored as-is.
 
@@ -2257,10 +2257,11 @@ groups D and F will influence each other.  Group G will influence nobody::
 So the ideal way to configure this is to set io.latency in groups A, B, and C.
 Generally you do not want to set a value lower than the latency your device
 supports.  Experiment to find the value that works best for your workload.
-Start at higher than the expected latency for your device and watch the
-avg_lat value in io.stat for your workload group to get an idea of the
-latency you see during normal operation.  Use the avg_lat value as a basis for
-your real setting, setting at 10-15% higher than the value in io.stat.
+Start at higher than the expected latency for your device and, with
+blkcg_debug_stats enabled, watch the avg_lat value in io.stat for your
+workload group to get an idea of the latency you see during normal operation.
+Use the avg_lat value as a basis for your real setting, setting at 10-15%
+higher than the value in io.stat.
 
 How IO Latency Throttling Works
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -2298,7 +2299,9 @@ IO Latency Interface Files
 
   io.stat
 	If the controller is enabled you will see extra stats in io.stat in
-	addition to the normal ones.
+	addition to the normal ones.  These debug stats are only emitted when
+	the blkcg_debug_stats module parameter is enabled (it is disabled by
+	default).
 
 	  depth
 		This is the current queue depth for the group.
@@ -2934,7 +2937,8 @@ include/linux/misc_cgroup.h.
 Misc Interface Files
 ~~~~~~~~~~~~~~~~~~~~
 
-Miscellaneous controller provides 3 interface files. If two misc resources (res_a and res_b) are registered then:
+Miscellaneous controller provides the following interface files. If two misc
+resources (res_a and res_b) are registered then:
 
   misc.capacity
         A read-only flat-keyed file shown only in the root cgroup.  It shows

kernel/cgroup/cpuset.c

@@ -2653,7 +2653,12 @@ void cpuset_update_tasks_nodemask(struct cpuset *cs)
 
 		migrate = is_memory_migrate(cs);
 
-		mpol_rebind_mm(mm, &cs->mems_allowed);
+		/*
+		 * For v1 we can have empty effective_mems, but we cannot
+		 * attach any tasks (see cpuset_can_attach_check()). For v2,
+		 * effective_mems is guaranteed to not be empty.
+		 */
+		mpol_rebind_mm(mm, &cs->effective_mems);
 		if (migrate)
 			cpuset_migrate_mm(mm, &cs->old_mems_allowed, &newmems);
 		else