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McKenney" To: Naresh Kamboju Subject: Re: rcu-torture: Internal error: Oops: 96000006 Message-ID: <20210122153704.GG2743@paulmck-ThinkPad-P72> References: <20210121185521.GQ2743@paulmck-ThinkPad-P72> <20210121213110.GB23234@willie-the-truck> <20210121214314.GW2743@paulmck-ThinkPad-P72> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210122_103706_848089_EA6B7DF8 X-CRM114-Status: GOOD ( 22.09 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: paulmck@kernel.org Cc: Mark Rutland , Peter Zijlstra , Catalin Marinas , open list , lkft-triage@lists.linaro.org, rcu@vger.kernel.org, Linux-Next Mailing List , Steven Rostedt , Vincenzo Frascino , Will Deacon , Ingo Molnar , Linux ARM Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, Jan 22, 2021 at 03:21:07PM +0530, Naresh Kamboju wrote: > On Fri, 22 Jan 2021 at 03:13, Paul E. McKenney wrote: > > > > On Thu, Jan 21, 2021 at 09:31:10PM +0000, Will Deacon wrote: > > > On Thu, Jan 21, 2021 at 10:55:21AM -0800, Paul E. McKenney wrote: > > > > On Thu, Jan 21, 2021 at 10:37:21PM +0530, Naresh Kamboju wrote: > > > > > While running rcu-torture test on qemu_arm64 and arm64 Juno-r2 device > > > > > the following kernel crash noticed. This started happening from Linux next > > > > > next-20210111 tag to next-20210121. > > > > > > > > > > metadata: > > > > > git branch: master > > > > > git repo: https://gitlab.com/Linaro/lkft/mirrors/next/linux-next > > > > > git describe: next-20210111 > > > > > kernel-config: https://builds.tuxbuild.com/1muTTn7AfqcWvH5x2Alxifn7EUH/config > > > > > > > > > > output log: > > > > > > > > > > [ 621.538050] mem_dump_obj() slab test: rcu_torture_stats = > > > > > ffff0000c0a3ac40, &rhp = ffff800012debe40, rhp = ffff0000c8cba000, &z > > > > > = ffff8000091ab8e0 > > > > > [ 621.546662] mem_dump_obj(ZERO_SIZE_PTR): > > > > > [ 621.546696] Unable to handle kernel NULL pointer dereference at > > > > > virtual address 0000000000000008 > > > > > > [...] > > > > > > > Huh. I am relying on virt_addr_valid() rejecting NULL pointers and > > > > things like ZERO_SIZE_PTR, which is defined as ((void *)16). It looks > > > > like your configuration rejects NULL as an invalid virtual address, > > > > but does not reject ZERO_SIZE_PTR. Is this the intent, given that you > > > > are not allowed to dereference a ZERO_SIZE_PTR? > > > > > > > > Adding the ARM64 guys on CC for their thoughts. > > > > > > Spooky timing, there was a thread _today_ about that: > > > > > > https://lore.kernel.org/r/ecbc7651-82c4-6518-d4a9-dbdbdf833b5b@arm.com > > > > Very good, then my workaround (shown below for Naresh's ease of testing) > > is only a short-term workaround. Yay! ;-) > > Paul, thanks for your (short-term workaround) patch. > > I have applied your patch and tested rcu-torture test on qemu_arm64 and > the reported issues has been fixed. May I add your Tested-by? And before I forget again, good to see the rcutorture testing on a non-x86 platform! Thanx, Paul _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel