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Date:   Wed, 22 Jul 2020 12:27:38 +0100
From:   Matthew Wilcox <willy@infradead.org>
To:     qiang.zhang@windriver.com
Cc:     akpm@linux-foundation.org, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm/dmapool.c: add lock protect in dma_pool_destroy
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On Wed, Jul 22, 2020 at 05:05:16PM +0800, qiang.zhang@windriver.com wrote:
> When traversing "pool->page" linked list, to prevent possible
> other path operations this list, causing it to be destroyed, we
> should add lock protect for this list in dma_pool_destroy func.

The pool is being destroyed.  If somebody else is trying to allocate from
it while it's in the middle of being destroyed, there is a larger problem
to solve, and it can't be solved in the dmapool code.