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[54.240.9.99]) by mx.google.com with ESMTPS id q27si2560254qkn.246.2019.04.08.08.15.12 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Mon, 08 Apr 2019 08:15:12 -0700 (PDT) Received-SPF: pass (google.com: domain of 01000169fd847a25-5933cc1e-a520-416a-b634-84b3e7ce9960-000000@amazonses.com designates 54.240.9.99 as permitted sender) client-ip=54.240.9.99; Authentication-Results: mx.google.com; dkim=pass header.i=@amazonses.com header.s=6gbrjpgwjskckoa6a5zn6fwqkn67xbtw header.b=GvgiXh2j; spf=pass (google.com: domain of 01000169fd847a25-5933cc1e-a520-416a-b634-84b3e7ce9960-000000@amazonses.com designates 54.240.9.99 as permitted sender) smtp.mailfrom=01000169fd847a25-5933cc1e-a520-416a-b634-84b3e7ce9960-000000@amazonses.com DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/simple; s=6gbrjpgwjskckoa6a5zn6fwqkn67xbtw; d=amazonses.com; t=1554736511; h=Date:From:To:cc:Subject:In-Reply-To:Message-ID:References:MIME-Version:Content-Type:Feedback-ID; bh=lNudCzZ4w2s8/H8+lpBX7L/o8a8N/r9Gfx4wno1thXs=; b=GvgiXh2jwzAKEcSIvSEHZ7wXwO53kEXUrIQ32sBEP9JQ5xZuwvt2G2bVkMYkRab/ s8KivUTDhpY3S/pzO5O2k7tEkQI0ZyRGpdsqWx71a9wJfL775CkbpHGn71j6vP8XsjD q7weJEid6EUbqwZjDvHiR2VVskTLBYw+21QKoko0= Date: Mon, 8 Apr 2019 15:15:11 +0000 From: Christopher Lameter X-X-Sender: cl@nuc-kabylake To: Linus Torvalds cc: Qian Cai , Andrew Morton , penberg@kernel.org, David Rientjes , iamjoonsoo.kim@lge.com, Tejun Heo , Linux-MM , Linux List Kernel Mailing Subject: Re: [PATCH] slab: fix a crash by reading /proc/slab_allocators In-Reply-To: Message-ID: <01000169fd847a25-5933cc1e-a520-416a-b634-84b3e7ce9960-000000@email.amazonses.com> References: <20190406225901.35465-1-cai@lca.pw> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-SES-Outgoing: 2019.04.08-54.240.9.99 Feedback-ID: 1.us-east-1.fQZZZ0Xtj2+TD7V5apTT/NrT6QKuPgzCT/IC7XYgDKI=:AmazonSES 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 Sun, 7 Apr 2019, Linus Torvalds wrote: > 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. This is only occurring with specially build kernels so that memory leaks can be investigated. The same is done with other tools (kasan and friends) today I guess and also the SLUB debugging tools are much more user friendly. So this means that some esoteric debugging feature of SLAB was broken.