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Thu, 21 Nov 2024 08:50:17 -0800 (PST) MIME-Version: 1.0 References: <20241120102325.3538-1-acarmina@redhat.com> <20241120102602.3e17f2d5@gandalf.local.home> <20241120164043.T1JuBALe@linutronix.de> In-Reply-To: <20241120164043.T1JuBALe@linutronix.de> From: Alessandro Carminati Date: Thu, 21 Nov 2024 17:50:06 +0100 Message-ID: Subject: Re: [PATCH] mm/kmemleak: Fix sleeping function called from invalid context in kmemleak_seq_show To: Sebastian Andrzej Siewior Cc: Steven Rostedt , Catalin Marinas , Andrew Morton , Clark Williams , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-rt-devel@lists.linux.dev, Thomas Weissschuh , Alessandro Carminati , Juri Lelli , Gabriele Paoloni , Eric Chanudet X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: ddiZBwnXf4rVdPd0lAmen23drmkVZq55KEe0GHySFKg_1732207818 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 452E340014 X-Stat-Signature: bht7uutuq5t4eznfma9codpexwj4cy1n X-Rspam-User: X-HE-Tag: 1732207780-298357 X-HE-Meta: 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 U4zi8qKQ iOVa8Izwkci41XmxcFI37x1WnJEnHc4ACscmYjoTIQ8ep/lrIcaiW0sdJ9GoFXS6MsCKCORW7Gw6V0YqbXuZ+eMpgiyB7VH6e0br9vOUEYIZDkuW2Lm+fvWh8cdJQyNwb5wFtZueXybfOuNyeEmkR5bSxvCPCZ/Rp5jVd9sxUJj7tVxxl4zed3yB89Ry6nLdbXOQDsJ5dCAYddQAkwieFL6Jrxex8XHcW+5V/ojnLNofvJpjIOt9RJ8Zjiyjfo30cPqazZZ2NHb9JJBmUanH0FSOdk7dQqdEcP/m4CRMqIS98tXHXUDAFuvk2H5TOGBYOzffyUnxPipECa6f8FEPkKtxHb4fI/SE/SSjljpoqeuYjFIdoSR1Cdo3CDg== 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: List-Subscribe: List-Unsubscribe: Hello Sebastian, On Wed, Nov 20, 2024 at 5:40=E2=80=AFPM Sebastian Andrzej Siewior wrote: > > On 2024-11-20 10:26:02 [-0500], Steven Rostedt wrote: > > The "%pK" dereferences a pointer and there's some SELinux hooks attache= d to > > that code. The problem is that the SELinux hooks take spinlocks. This w= ould > > not have been an issue if it wasn't for that "%pK" in the format. > > That is missing check and I think Thomas Weissschuh wanted to add it. So > we don't call into selinux. Your comment confuses me a bit, as I'm unsure what Thomas is actually working on. Am I correct in assuming he's addressing a fix in lib/vsprintf.c to ensure that sleeping functions aren't called, allowing these functions to work in any context? However, his mention of "This fix for kmemleak is still needed as the pointers in the kmemleak report are useful" adds to my confusion. Meanwhile, Steven suggests reworking SELinux to resolve the issue. Could you clarify what you mean by "So we don't call into selinux"? > > Sebastian > Thanks --=20 --- 172