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workqueue: Fixes for v6.7-rc4

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Just one patch to fix a bug which can crash the kernel if the housekeeping
 and wq_unbound_cpu cpumask configuration combination leaves the latter
 empty.
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Merge tag 'wq-for-6.7-rc4-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq

Pull workqueue fix from Tejun Heo:
 "Just one patch to fix a bug which can crash the kernel if the
  housekeeping and wq_unbound_cpu cpumask configuration combination
  leaves the latter empty"

* tag 'wq-for-6.7-rc4-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
  workqueue: Make sure that wq_unbound_cpumask is never empty
This commit is contained in:
Linus Torvalds 2023-12-07 12:36:32 -08:00
commit e0348c1f68
1 changed files with 15 additions and 7 deletions
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22
kernel/workqueue.c
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@ -1684,9 +1684,6 @@ static int wq_select_unbound_cpu(int cpu)
pr_warn_once("workqueue: round-robin CPU selection forced, expect performance impact\n");
}
if (cpumask_empty(wq_unbound_cpumask))
return cpu;
new_cpu = __this_cpu_read(wq_rr_cpu_last);
new_cpu = cpumask_next_and(new_cpu, wq_unbound_cpumask, cpu_online_mask);
if (unlikely(new_cpu >= nr_cpu_ids)) {
@ -6515,6 +6512,17 @@ static inline void wq_watchdog_init(void) { }
#endif /* CONFIG_WQ_WATCHDOG */
static void __init restrict_unbound_cpumask(const char *name, const struct cpumask *mask)
{
if (!cpumask_intersects(wq_unbound_cpumask, mask)) {
pr_warn("workqueue: Restricting unbound_cpumask (%*pb) with %s (%*pb) leaves no CPU, ignoring\n",
cpumask_pr_args(wq_unbound_cpumask), name, cpumask_pr_args(mask));
return;
}
cpumask_and(wq_unbound_cpumask, wq_unbound_cpumask, mask);
}
/**
* workqueue_init_early - early init for workqueue subsystem
*
@ -6534,11 +6542,11 @@ void __init workqueue_init_early(void)
BUILD_BUG_ON(__alignof__(struct pool_workqueue) < __alignof__(long long));
BUG_ON(!alloc_cpumask_var(&wq_unbound_cpumask, GFP_KERNEL));
cpumask_copy(wq_unbound_cpumask, housekeeping_cpumask(HK_TYPE_WQ));
cpumask_and(wq_unbound_cpumask, wq_unbound_cpumask, housekeeping_cpumask(HK_TYPE_DOMAIN));
cpumask_copy(wq_unbound_cpumask, cpu_possible_mask);
restrict_unbound_cpumask("HK_TYPE_WQ", housekeeping_cpumask(HK_TYPE_WQ));
restrict_unbound_cpumask("HK_TYPE_DOMAIN", housekeeping_cpumask(HK_TYPE_DOMAIN));
if (!cpumask_empty(&wq_cmdline_cpumask))
cpumask_and(wq_unbound_cpumask, wq_unbound_cpumask, &wq_cmdline_cpumask);
restrict_unbound_cpumask("workqueue.unbound_cpus", &wq_cmdline_cpumask);
pwq_cache = KMEM_CACHE(pool_workqueue, SLAB_PANIC);