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([2620:15c:2c1:200:55c7:81e6:c7d8:94b]) by smtp.gmail.com with ESMTPSA id g4sm4832243pfm.115.2019.04.18.16.18.01 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 18 Apr 2019 16:18:02 -0700 (PDT) Subject: Re: [PATCH v4 1/2] mm: refactor __vunmap() to avoid duplicated call to find_vm_area() To: Andrew Morton , Matthew Wilcox Cc: Roman Gushchin , linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@fb.com, Johannes Weiner , Vlastimil Babka , Roman Gushchin , Christoph Hellwig , Joel Fernandes References: <20190417194002.12369-1-guro@fb.com> <20190417194002.12369-2-guro@fb.com> <20190417145827.8b1c83bf22de8ba514f157e3@linux-foundation.org> <20190418111834.GE7751@bombadil.infradead.org> <20190418152431.c583ef892a8028c662db3e6a@linux-foundation.org> From: Eric Dumazet Message-ID: <05c40b0b-3621-6c07-346b-478679949d92@gmail.com> Date: Thu, 18 Apr 2019 16:17:59 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20190418152431.c583ef892a8028c662db3e6a@linux-foundation.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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.