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io_uring/io-wq: do not allow pinning outside of cpuset

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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: da64d6db3b ("io_uring: One wqe per wq")
Signed-off-by: Felix Moessbauer <felix.moessbauer@siemens.com>
Link: https://lore.kernel.org/r/20240910171157.166423-2-felix.moessbauer@siemens.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Felix Moessbauer 2024-09-10 19:11:56 +02:00 committed by Jens Axboe
parent 90bfb28d5f
commit 0997aa5497
1 changed files with 18 additions and 5 deletions
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23
io_uring/io-wq.c
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@ -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;
}
/*