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Date:   Sat, 18 Jun 2022 11:34:41 +0100
From:   Matthew Wilcox <willy@infradead.org>
To:     Miaohe Lin <linmiaohe@huawei.com>
Cc:     akpm@linux-foundation.org, linux-fsdevel@vger.kernel.org,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] filemap: obey mapping->invalidate_lock lock/unlock order
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On Sat, Jun 18, 2022 at 04:38:20PM +0800, Miaohe Lin wrote:
> The invalidate_locks of two mappings should be unlocked in reverse order
> relative to the locking order in filemap_invalidate_lock_two(). Modifying

Why?  It's perfectly valid to lock(A) lock(B) unlock(A) unlock(B).
If it weren't we'd have lockdep check it and complain.