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[71.184.117.43]) by smtp.gmail.com with ESMTPSA id g12sm21105028qkk.85.2019.04.11.04.08.23 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 11 Apr 2019 04:08:24 -0700 (PDT) Subject: Re: [PATCH] slab: fix an infinite loop in leaks_show() To: Vlastimil Babka , akpm@linux-foundation.org Cc: cl@linux.com, penberg@kernel.org, rientjes@google.com, iamjoonsoo.kim@lge.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, "Tobin C. Harding" , Linus Torvalds , Michal Hocko References: <20190411032635.10325-1-cai@lca.pw> <43517646-a808-bccd-a05e-1b583fc411c7@suse.cz> From: Qian Cai Message-ID: <02049855-d37f-965e-12f7-f2549cae73ec@lca.pw> Date: Thu, 11 Apr 2019 07:08:23 -0400 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <43517646-a808-bccd-a05e-1b583fc411c7@suse.cz> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Bogosity: Ham, tests=bogofilter, spamicity=0.000001, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 4/11/19 4:20 AM, Vlastimil Babka wrote: > On 4/11/19 5:26 AM, Qian Cai wrote: >> "cat /proc/slab_allocators" could hang forever on SMP machines with >> kmemleak or object debugging enabled due to other CPUs running do_drain() >> will keep making kmemleak_object or debug_objects_cache dirty and unable >> to escape the first loop in leaks_show(), > > So what if we don't remove SLAB (yet?) but start removing the debugging > functionality that has been broken for years and nobody noticed. I think > Linus already mentioned that we remove at least the > /proc/slab_allocators file... In my experience, 2-year isn't that long for debugging features to be silently broken with SLAB where kmemleak is broken for more than 4-year there. See 92d1d07daad6 ("mm/slab.c: kmemleak no scan alien caches").