Re: [PATCH v2 2/9] x86: numa: check the node id consistently for x86
From: Peter Zijlstra <peterz@infradead.org>
Date: 2019-08-31 08:56:54
Also in:
linux-alpha, linux-arm-kernel, linux-mips, linux-s390, linux-sh, lkml, sparclinux
On Sat, Aug 31, 2019 at 01:58:16PM +0800, Yunsheng Lin wrote:
According to Section 6.2.14 from ACPI spec 6.3 [1], the setting of proximity domain is optional, as below: This optional object is used to describe proximity domain associations within a machine. _PXM evaluates to an integer that identifies a device as belonging to a Proximity Domain defined in the System Resource Affinity Table (SRAT).
That's just words.. what does it actually mean?
quoted hunk ↗ jump to hunk
This patch checks node id with the below case before returning node_to_cpumask_map[node]: 1. if node_id >= nr_node_ids, return cpu_none_mask 2. if node_id < 0, return cpu_online_mask 3. if node_to_cpumask_map[node_id] is NULL, return cpu_online_mask [1] https://uefi.org/sites/default/files/resources/ACPI_6_3_final_Jan30.pdf Signed-off-by: Yunsheng Lin <redacted> --- arch/x86/include/asm/topology.h | 6 ++++++ arch/x86/mm/numa.c | 2 +- 2 files changed, 7 insertions(+), 1 deletion(-)diff --git a/arch/x86/include/asm/topology.h b/arch/x86/include/asm/topology.h index 4b14d23..f36e9c8 100644 --- a/arch/x86/include/asm/topology.h +++ b/arch/x86/include/asm/topology.h@@ -69,6 +69,12 @@ extern const struct cpumask *cpumask_of_node(int node); /* Returns a pointer to the cpumask of CPUs on Node 'node'. */ static inline const struct cpumask *cpumask_of_node(int node) { + if (node >= nr_node_ids) + return cpu_none_mask; + + if (node < 0 || !node_to_cpumask_map[node]) + return cpu_online_mask; + return node_to_cpumask_map[node]; } #endif
I _reallly_ hate this. Users are expected to use valid numa ids. Now we're adding all this checking to all users. Why do we want to do that? Using '(unsigned)node >= nr_nods_ids' is an error.
quoted hunk ↗ jump to hunk
diff --git a/arch/x86/mm/numa.c b/arch/x86/mm/numa.c index e6dad60..5e393d2 100644 --- a/arch/x86/mm/numa.c +++ b/arch/x86/mm/numa.c@@ -868,7 +868,7 @@ const struct cpumask *cpumask_of_node(int node) dump_stack(); return cpu_none_mask; } - if (node_to_cpumask_map[node] == NULL) { + if (node < 0 || !node_to_cpumask_map[node]) { printk(KERN_WARNING "cpumask_of_node(%d): no node_to_cpumask_map!\n", node);-- 2.8.1