From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sebastian Capella Subject: Re: [PATCH RFC v1 3/3] ARM hibernation / suspend-to-disk Date: Fri, 21 Feb 2014 20:37:14 -0800 Message-ID: <20140222043714.19852.67450@capellas-linux> References: <1392774729-3235-1-git-send-email-sebastian.capella@linaro.org> <1392774729-3235-4-git-send-email-sebastian.capella@linaro.org> <20140219161254.GB19343@e102568-lin.cambridge.arm.com> <20140219193315.3732.21819@capellas-linux> <20140220162754.GC15994@e102568-lin.cambridge.arm.com> <20140221183956.29890.80931@capellas-linux> <20140221235911.14777.13919@capellas-linux> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20140221235911.14777.13919@capellas-linux> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=m.gmane.org@lists.infradead.org To: Sebastian Capella , Lorenzo Pieralisi Cc: Len Brown , "linaro-kernel@lists.linaro.org" , Russell King , Jonathan Austin , "linux-pm@vger.kernel.org" , Will Deacon , Nicolas Pitre , "Rafael J. Wysocki" , "linux-kernel@vger.kernel.org" , Uwe Kleine-K?nig , Russ Dill , Pavel Machek , Catalin Marinas , Santosh Shilimkar , Stephen Boyd , "linux-arm-kernel@lists.infradead.org" List-Id: linux-pm@vger.kernel.org Quoting Sebastian Capella (2014-02-21 15:59:11) > - Cyril Chemparathy as his email is bouncing back to me. > > Quoting Sebastian Capella (2014-02-21 10:39:56) > > Quoting Lorenzo Pieralisi (2014-02-20 08:27:55) > > > > > > + cpu_switch_mm(idmap_pgd, &init_mm); > [ ... ] > > I can try removing it and seeing if there are side effects. > > FYI, It's definitely hanging with this removed, still looking. I see when we reach this call, the 1st level page table @ TTBR0 is located at different memory locations each run (expected). If we omit the cpu_switch_mm we're corrupting the page table causing the observed intermittent failures. I believe these match the corruption you expected. The reason this doesn't happen when I leave the call is that idmap_pgd is always at the same memory location. I expect this is because it's allocated during init. I've seen the same address 50/50 times for idmap_pgd. I don't think it is correct to rely on this behavior. Would it be appropriate to use the swapper_pg_dir directly in place of idmap_pgd? - I do not see any modification to the swapper_pg_dir contents in the code that would change from init time. - swapper_pg_dir is always at the same offset. Ideally we should have no issue with overwriting it with identical data. I've run a couple hundred test loops using swapper_pg_dir and so far there are no failures. Thanks, Sebastian From mboxrd@z Thu Jan 1 00:00:00 1970 From: sebastian.capella@linaro.org (Sebastian Capella) Date: Fri, 21 Feb 2014 20:37:14 -0800 Subject: [PATCH RFC v1 3/3] ARM hibernation / suspend-to-disk In-Reply-To: <20140221235911.14777.13919@capellas-linux> References: <1392774729-3235-1-git-send-email-sebastian.capella@linaro.org> <1392774729-3235-4-git-send-email-sebastian.capella@linaro.org> <20140219161254.GB19343@e102568-lin.cambridge.arm.com> <20140219193315.3732.21819@capellas-linux> <20140220162754.GC15994@e102568-lin.cambridge.arm.com> <20140221183956.29890.80931@capellas-linux> <20140221235911.14777.13919@capellas-linux> Message-ID: <20140222043714.19852.67450@capellas-linux> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Quoting Sebastian Capella (2014-02-21 15:59:11) > - Cyril Chemparathy as his email is bouncing back to me. > > Quoting Sebastian Capella (2014-02-21 10:39:56) > > Quoting Lorenzo Pieralisi (2014-02-20 08:27:55) > > > > > > + cpu_switch_mm(idmap_pgd, &init_mm); > [ ... ] > > I can try removing it and seeing if there are side effects. > > FYI, It's definitely hanging with this removed, still looking. I see when we reach this call, the 1st level page table @ TTBR0 is located at different memory locations each run (expected). If we omit the cpu_switch_mm we're corrupting the page table causing the observed intermittent failures. I believe these match the corruption you expected. The reason this doesn't happen when I leave the call is that idmap_pgd is always at the same memory location. I expect this is because it's allocated during init. I've seen the same address 50/50 times for idmap_pgd. I don't think it is correct to rely on this behavior. Would it be appropriate to use the swapper_pg_dir directly in place of idmap_pgd? - I do not see any modification to the swapper_pg_dir contents in the code that would change from init time. - swapper_pg_dir is always at the same offset. Ideally we should have no issue with overwriting it with identical data. I've run a couple hundred test loops using swapper_pg_dir and so far there are no failures. Thanks, Sebastian