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| author | Yury Norov <yury.norov@gmail.com> | 2023-08-19 07:12:35 -0700 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2023-09-15 13:48:10 +0200 |
| commit | 617f2c38cb5ce60226042081c09e2ee3a90d03f8 (patch) | |
| tree | 48ef1b7714d3e7dd1bfb0a25f9b55e0bcc2d6147 | |
| parent | d1db9fb432d50b0eecdfdd85d17cc15a59cc093b (diff) | |
| download | lwn-617f2c38cb5ce60226042081c09e2ee3a90d03f8.tar.gz lwn-617f2c38cb5ce60226042081c09e2ee3a90d03f8.zip | |
sched/topology: Fix sched_numa_find_nth_cpu() in CPU-less case
When the node provided by user is CPU-less, corresponding record in
sched_domains_numa_masks is not set. Trying to dereference it in the
following code leads to kernel crash.
To avoid it, start searching from the nearest node with CPUs.
Fixes: cd7f55359c90 ("sched: add sched_numa_find_nth_cpu()")
Reported-by: Yicong Yang <yangyicong@hisilicon.com>
Reported-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Yury Norov <yury.norov@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Yicong Yang <yangyicong@hisilicon.com>
Cc: Mel Gorman <mgorman@suse.de>
Link: https://lore.kernel.org/r/20230819141239.287290-4-yury.norov@gmail.com
Closes: https://lore.kernel.org/lkml/CAAH8bW8C5humYnfpW3y5ypwx0E-09A3QxFE1JFzR66v+mO4XfA@mail.gmail.com/T/
Closes: https://lore.kernel.org/lkml/ZMHSNQfv39HN068m@yury-ThinkPad/T/#mf6431cb0b7f6f05193c41adeee444bc95bf2b1c4
| -rw-r--r-- | kernel/sched/topology.c | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c index 05a5bc678c08..423d08947962 100644 --- a/kernel/sched/topology.c +++ b/kernel/sched/topology.c @@ -2122,12 +2122,16 @@ static int hop_cmp(const void *a, const void *b) */ int sched_numa_find_nth_cpu(const struct cpumask *cpus, int cpu, int node) { - struct __cmp_key k = { .cpus = cpus, .node = node, .cpu = cpu }; + struct __cmp_key k = { .cpus = cpus, .cpu = cpu }; struct cpumask ***hop_masks; int hop, ret = nr_cpu_ids; rcu_read_lock(); + /* CPU-less node entries are uninitialized in sched_domains_numa_masks */ + node = numa_nearest_node(node, N_CPU); + k.node = node; + k.masks = rcu_dereference(sched_domains_numa_masks); if (!k.masks) goto unlock; |