void idr_preload(gfp_t gfp_mask)
{
	/*
	 * Consuming preload buffer from non-process context breaks preload
	 * allocation guarantee.  Disallow usage from those contexts.
	 */
	WARN_ON_ONCE(in_interrupt());
	might_sleep_if(gfp_mask & __GFP_WAIT);

	preempt_disable();

	/*
	 * idr_alloc() is likely to succeed w/o full idr_layer buffer and
	 * return value from idr_alloc() needs to be checked for failure
	 * anyway.  Silently give up if allocation fails.  The caller can
	 * treat failures from idr_alloc() as if idr_alloc() were called
	 * with @gfp_mask which should be enough.
	 */
	while (__this_cpu_read(idr_preload_cnt) < MAX_IDR_FREE) {
		struct idr_layer *new;

		preempt_enable();
		new = kmem_cache_zalloc(idr_layer_cache, gfp_mask);
		preempt_disable();
		if (!new)
			break;

		/* link the new one to per-cpu preload list */
		new->ary[0] = __this_cpu_read(idr_preload_head);
		__this_cpu_write(idr_preload_head, new);
		__this_cpu_inc(idr_preload_cnt);
	}
}
void idr_preload(gfp_t gfp_mask)
{
	 
	WARN_ON_ONCE(in_interrupt());
	might_sleep_if(gfp_mask & __GFP_WAIT);

	preempt_disable();

	 
	while (__this_cpu_read(idr_preload_cnt) < MAX_IDR_FREE) {
		struct idr_layer *new;

		preempt_enable();
		new = kmem_cache_zalloc(idr_layer_cache, gfp_mask);
		preempt_disable();
		if (!new)
			break;

		 
		new->ary[0] = __this_cpu_read(idr_preload_head);
		__this_cpu_write(idr_preload_head, new);
		__this_cpu_inc(idr_preload_cnt);
	}
}