The io worker threads are userland threads that just never exit to the
userland. By that, they are also assigned to a cgroup (the group of the
creating task).
When changing the affinity of the io_wq thread via syscall, we must only
allow cpumasks within the limits defined by the cpuset controller of the
cgroup (if enabled).
Fixes: da64d6db3bd3 ("io_uring: One wqe per wq")
Signed-off-by: Felix Moessbauer <felix.moessbauer@xxxxxxxxxxx>
---
io_uring/io-wq.c | 23 ++++++++++++++++++-----
1 file changed, 18 insertions(+), 5 deletions(-)
diff --git a/io_uring/io-wq.c b/io_uring/io-wq.c
index f1e7c670add8..c7055a8895d7 100644
--- a/io_uring/io-wq.c
+++ b/io_uring/io-wq.c
@@ -13,6 +13,7 @@
#include <linux/slab.h>
#include <linux/rculist_nulls.h>
#include <linux/cpu.h>
+#include <linux/cpuset.h>
#include <linux/task_work.h>
#include <linux/audit.h>
#include <linux/mmu_context.h>
@@ -1322,17 +1323,29 @@ static int io_wq_cpu_offline(unsigned int cpu, struct hlist_node *node)
int io_wq_cpu_affinity(struct io_uring_task *tctx, cpumask_var_t mask)
{
+ cpumask_var_t allowed_mask;
+ int ret = 0;
+
if (!tctx || !tctx->io_wq)
return -EINVAL;
+ if (!alloc_cpumask_var(&allowed_mask, GFP_KERNEL))
+ return -ENOMEM;
+
rcu_read_lock();
- if (mask)
- cpumask_copy(tctx->io_wq->cpu_mask, mask);
- else
- cpumask_copy(tctx->io_wq->cpu_mask, cpu_possible_mask);
+ cpuset_cpus_allowed(tctx->io_wq->task, allowed_mask);
+ if (mask) {
+ if (cpumask_subset(mask, allowed_mask))
+ cpumask_copy(tctx->io_wq->cpu_mask, mask);
+ else
+ ret = -EINVAL;
+ } else {
+ cpumask_copy(tctx->io_wq->cpu_mask, allowed_mask);
+ }
rcu_read_unlock();
- return 0;
+ free_cpumask_var(allowed_mask);
+ return ret;
}
/*
--
2.39.2
