From 27600805e62f800bacf990354632eae4e487d34c Mon Sep 17 00:00:00 2001 From: Yazen Ghannam Date: Thu, 3 Sep 2026 10:43:25 -0500 Subject: x86/amd_node: Fix PCI device reference counting in amd_smn_init() The local "root" pointer is a temporary variable used during the device search. Therefore, refcount related to the search iterators should be cleaned up after the search is complete. Use the __free() cleanup macro to ensure the refcount is decremented when the temporary pointer goes out of scope. Additionally, increment the refcount when caching a root pointer. This ensures the in-use refcount is separate from the temporary search refcounting. Finally, drop the redundant "root = NULL" before the second search loop. The pci_get_class() iterator always decrements the refcount of its "from" argument, so the first loop can only fall through with "root" already NULL. Fixes: 0a4b61d9c2e4 ("x86/amd_node: Fix AMD root device caching") Closes: https://sashiko.dev/#/patchset/20260806160159.230453-1-jason.andryuk%40amd.com Reported-by: Sashiko Assisted-by: LLM Signed-off-by: Yazen Ghannam Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Mario Limonciello (AMD) Cc: Link: https://patch.msgid.link/20260903154325.74343-1-yazen.ghannam@amd.com --- Documentation/admin-guide/numastat.rst | 55 ++++++++++++++++++++++++++++++++++ 1 file changed, 55 insertions(+) create mode 100644 Documentation/admin-guide/numastat.rst (limited to 'Documentation/admin-guide/numastat.rst') diff --git a/Documentation/admin-guide/numastat.rst b/Documentation/admin-guide/numastat.rst new file mode 100644 index 000000000..08ec2c2bd --- /dev/null +++ b/Documentation/admin-guide/numastat.rst @@ -0,0 +1,55 @@ +=============================== +Numa policy hit/miss statistics +=============================== + +/sys/devices/system/node/node*/numastat + +All units are pages. Hugepages have separate counters. + +The numa_hit, numa_miss and numa_foreign counters reflect how well processes +are able to allocate memory from nodes they prefer. If they succeed, numa_hit +is incremented on the preferred node, otherwise numa_foreign is incremented on +the preferred node and numa_miss on the node where allocation succeeded. + +Usually preferred node is the one local to the CPU where the process executes, +but restrictions such as mempolicies can change that, so there are also two +counters based on CPU local node. local_node is similar to numa_hit and is +incremented on allocation from a node by CPU on the same node. other_node is +similar to numa_miss and is incremented on the node where allocation succeeds +from a CPU from a different node. Note there is no counter analogical to +numa_foreign. + +In more detail: + +=============== ============================================================ +numa_hit A process wanted to allocate memory from this node, + and succeeded. + +numa_miss A process wanted to allocate memory from another node, + but ended up with memory from this node. + +numa_foreign A process wanted to allocate on this node, + but ended up with memory from another node. + +local_node A process ran on this node's CPU, + and got memory from this node. + +other_node A process ran on a different node's CPU + and got memory from this node. + +interleave_hit Interleaving wanted to allocate from this node + and succeeded. +=============== ============================================================ + +For easier reading you can use the numastat utility from the numactl package +(http://oss.sgi.com/projects/libnuma/). Note that it only works +well right now on machines with a small number of CPUs. + +Note that on systems with memoryless nodes (where a node has CPUs but no +memory) the numa_hit, numa_miss and numa_foreign statistics can be skewed +heavily. In the current kernel implementation, if a process prefers a +memoryless node (i.e. because it is running on one of its local CPU), the +implementation actually treats one of the nearest nodes with memory as the +preferred node. As a result, such allocation will not increase the numa_foreign +counter on the memoryless node, and will skew the numa_hit, numa_miss and +numa_foreign statistics of the nearest node. -- cgit v1.3.1