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Thu, 09 Jun 2022 15:16:51 -0700 (PDT) Date: Thu, 9 Jun 2022 22:16:47 +0000 In-Reply-To: Message-Id: <20220609221647.lqxljj4wlb6mcuvr@google.com> Mime-Version: 1.0 References: <20220609191221.rv3lqbhipnvvzt67@google.com> Subject: Re: [next] arm64: boot failed - next-20220606 From: Shakeel Butt To: Roman Gushchin Cc: Naresh Kamboju , Linux-Next Mailing List , open list , regressions@lists.linux.dev, lkft-triage@lists.linaro.org, Linux ARM , linux-mm , Stephen Rothwell , Andrew Morton , Ard Biesheuvel , Arnd Bergmann , Catalin Marinas , Raghuram Thammiraju , Mark Brown , Will Deacon , Vasily Averin , Qian Cai X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220609_151658_115887_A3EC853E X-CRM114-Status: GOOD ( 19.11 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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 Thu, Jun 09, 2022 at 03:05:08PM -0700, Roman Gushchin wrote: > On Thu, Jun 09, 2022 at 07:12:21PM +0000, Shakeel Butt wrote: > > On Thu, Jun 09, 2022 at 10:56:09AM -0700, Roman Gushchin wrote: > > > On Thu, Jun 09, 2022 at 10:47:35AM -0700, Shakeel Butt wrote: > > > > On Thu, Jun 9, 2022 at 10:27 AM Roman Gushchin wrote: > > > > > > > > > [...] > > > > > +struct mem_cgroup *mem_cgroup_from_obj(void *p) > > > > > +{ > > > > > + struct folio *folio; > > > > > + > > > > > + if (mem_cgroup_disabled()) > > > > > + return NULL; > > > > > + > > > > > + if (unlikely(is_vmalloc_addr(p))) > > > > > + folio = page_folio(vmalloc_to_page(p)); > > > > > > > > Do we need to check for NULL from vmalloc_to_page(p)? > > > > > > Idk, can it realistically return NULL after is_vmalloc_addr() returned true? > > > I would be surprised, but maybe I'm missing something. > > > > is_vmalloc_addr() is simply checking the range and some buggy caller can > > provide an unmapped address within the range. Maybe VM_BUG_ON() should > > be good enough (though no strong opinion either way). > > No strong opinion here as well, but I think we don't have to be too defensive > here. Actually we'll know anyway, unlikely a null pointer dereference will be > unnoticed. And it's not different to calling mem_cgroup_from_obj() with some > random invalid address now. > Sounds good. You can add my ack when you send the official version of the patch. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel