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[209.85.167.44]) by smtp.gmail.com with ESMTPSA id q5sm5833786lfm.16.2019.04.07.22.35.51 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 07 Apr 2019 22:35:52 -0700 (PDT) Received: by mail-lf1-f44.google.com with SMTP id g7so8444621lfh.10 for ; Sun, 07 Apr 2019 22:35:51 -0700 (PDT) X-Received: by 2002:a19:f512:: with SMTP id j18mr9036020lfb.48.1554701750359; Sun, 07 Apr 2019 22:35:50 -0700 (PDT) MIME-Version: 1.0 References: <20190406225901.35465-1-cai@lca.pw> In-Reply-To: <20190406225901.35465-1-cai@lca.pw> From: Linus Torvalds Date: Sun, 7 Apr 2019 19:35:34 -1000 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH] slab: fix a crash by reading /proc/slab_allocators To: Qian Cai Cc: Andrew Morton , Christoph Lameter , penberg@kernel.org, David Rientjes , iamjoonsoo.kim@lge.com, Tejun Heo , Linux-MM , Linux List Kernel Mailing Content-Type: text/plain; charset="UTF-8" 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 Sat, Apr 6, 2019 at 12:59 PM Qian Cai wrote: > > The commit 510ded33e075 ("slab: implement slab_root_caches list") > changes the name of the list node within "struct kmem_cache" from > "list" to "root_caches_node", but leaks_show() still use the "list" > which causes a crash when reading /proc/slab_allocators. The patch does seem to be correct, and I have applied it. However, it does strike me that apparently this wasn't caught for two years. Which makes me wonder whether we should (once again) discuss just removing SLAB entirely, or at least removing the /proc/slab_allocators file. Apparently it has never been used in the last two years. At some point a "this can't have worked if anybody ever tried to use it" situation means that the code should likely be excised. Qian, how did you end up noticing and debugging this? Linus