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Subject: Re: [PATCH v4 1/2] mm: refactor __vunmap() to avoid duplicated call
 to find_vm_area()
To:     Andrew Morton <akpm@linux-foundation.org>,
        Matthew Wilcox <willy@infradead.org>
Cc:     Roman Gushchin <guroan@gmail.com>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, kernel-team@fb.com,
        Johannes Weiner <hannes@cmpxchg.org>,
        Vlastimil Babka <vbabka@suse.cz>, Roman Gushchin <guro@fb.com>,
        Christoph Hellwig <hch@lst.de>,
        Joel Fernandes <joelaf@google.com>
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 <20190418111834.GE7751@bombadil.infradead.org>
 <20190418152431.c583ef892a8028c662db3e6a@linux-foundation.org>
From:   Eric Dumazet <eric.dumazet@gmail.com>
Message-ID: <05c40b0b-3621-6c07-346b-478679949d92@gmail.com>
Date:   Thu, 18 Apr 2019 16:17:59 -0700
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On 04/18/2019 03:24 PM, Andrew Morton wrote:

> afaict, vfree() will only do a mutex_trylock() in
> try_purge_vmap_area_lazy().  So does vfree actually sleep in any
> situation?  Whether or not local interrupts are enabled?

We would be in a big trouble if vfree() could potentially sleep...

Random example : __free_fdtable() called from rcu callback.