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[58.6.248.8]) by smtp.gmail.com with ESMTPSA id e15-20020a056a0000cf00b00574ab0e053bsm5068095pfj.187.2022.12.11.23.19.51 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 11 Dec 2022 23:19:52 -0800 (PST) Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Mon, 12 Dec 2022 17:19:48 +1000 Message-Id: Subject: Re: [Bug 214913] [xfstests generic/051] BUG: Kernel NULL pointer dereference on read at 0x00000108 NIP [c0000000000372e4] tm_cgpr_active+0x14/0x40 From: "Nicholas Piggin" To: , X-Mailer: aerc 0.13.0 References: In-Reply-To: X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Eric Biederman Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Mon Dec 12, 2022 at 3:57 PM AEST, wrote: > https://bugzilla.kernel.org/show_bug.cgi?id=3D214913 > > --- Comment #9 from Michael Ellerman (michael@ellerman.id.au) --- > I assume it's an io_uring IO worker. > > They're created via create_io_worker() -> create_io_thread(). > > They pass a non-NULL `args->fn` to copy_process() -> copy_thread(), so we= end > up in the "kernel thread" branch of the if, which sets p->thread.regs =3D= NULL. Hmm, you might be right. These things are created with the memory and thread / signal context shared with the userspace process. Still doesn't seem like they should be involved in core dumping though, pt_regs would have no meaning even if we did set something there. How best to catch these and filter them out of the core dump? Check for PF_IO_WORKER in the coredump gathering? Thanks, Nick