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SubjectRe: [PATCHv2 09/11] dmapool: simplify freeing
> @@ -280,14 +268,14 @@ void dma_pool_destroy(struct dma_pool *pool)
> mutex_unlock(&pools_reg_lock);
>
> list_for_each_entry_safe(page, tmp, &pool->page_list, page_list) {
> + if (!is_page_busy(page))
> + dma_free_coherent(pool->dev, pool->allocation,
> + page->vaddr, page->dma);
> + else
> dev_err(pool->dev, "%s %s, %p busy\n", __func__,
> pool->name, page->vaddr);
> + list_del(&page->page_list);
> + kfree(page);

Hmm. The is_page_busy case is really a should not happen case.
What is the benefit of skipping the dma_free_coherent and leaking
memory here, vs letting KASAN and friends see the free and possibly
help with debugging? In other words, why is this not:

WARN_ON_ONCE(is_page_busy(page));
dma_free_coherent(pool->dev, pool->allocation, page->vaddr,
page->dma);
...

> page->in_use--;
> *(int *)vaddr = page->offset;
> page->offset = offset;
> - /*
> - * Resist a temptation to do
> - * if (!is_page_busy(page)) pool_free_page(pool, page);
> - * Better have a few empty pages hang around.
> - */

This doesn't look related to the rest, or am I missing something?

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