From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sai Prakash Ranjan Subject: Re: Crash in msm serial on dragonboard with ftrace bootargs Date: Wed, 17 Oct 2018 17:08:09 +0530 Message-ID: <2a23cd74-7364-0fb7-3c7b-7be79a881073@codeaurora.org> References: <1cae8f10-55f5-20ce-9105-30af6f88bd6e@codeaurora.org> <20181016112928.4b52afb5@gandalf.local.home> <20181017101355.GA230639@joelaf.mtv.corp.google.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20181017101355.GA230639@joelaf.mtv.corp.google.com> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Joel Fernandes , Kees Cook Cc: Steven Rostedt , Stephen Boyd , Bjorn Andersson , Andy Gross , David Brown , Jiri Slaby , "Ivan T. Ivanov" , Geliang Tang , Greg Kroah-Hartman , Pramod Gurav , linux-arm-msm@vger.kernel.org, linux-soc@vger.kernel.org, "open list:SERIAL DRIVERS" , LKML , Rajendra Nayak , Vivek Gautam , Sibi Sankar List-Id: linux-arm-msm@vger.kernel.org On 10/17/2018 3:43 PM, Joel Fernandes wrote: > Hi Kees, > > On Tue, Oct 16, 2018 at 10:02:53AM -0700, Kees Cook wrote: >> On Tue, Oct 16, 2018 at 8:29 AM, Steven Rostedt wrote: >>> On Tue, 16 Oct 2018 17:08:25 +0530 >>> Sai Prakash Ranjan wrote: >>>> One more thing is for pstore dmesg-ramoops, I had to change >>>> late_initcall to postcore_initcall which brings the question as to why >>>> we changed to late_initcall? >>>> Simple git blame shows to support crypto compress api, but is it really >>>> helpful? A lot of boottime issues can be caught with pstore enabled at >>>> postcore_initcall rather than late_initcall, this backtrace >>>> is just one example. Is there any way we could change this? >>> >>> Does it break if the crypto is not initialized? Perhaps add a command >>> line flag to have it happen earlier: >>> >>> ramoops=earlyinit >>> >>> and add a postcore_initcall that checks if that flag is set, and if so, >>> it does the work then, and the late_initcall() will do nothing. >>> >>> That way, you can still have unmodified kernels use pstore when it >>> crashes at boot up. >> >> Even better, if we could find a way to make it work with a late >> initialization of compression (i.e. postcore_initcall() by default >> means anything caught would be uncompressed, but anything after >> late_initcall() would be compressed). I'd be very happy to review >> patches for that! > > What do you think about the (untested) patch below? It seems to me that it > should solve the issue of missing early crash dumps, but I have not tested it > yet. Sai, would you mind trying it out and let me know if you can see the > early crash dumps properly now? > > ----8<--- > From: "Joel Fernandes (Google)" > Subject: [RFC] pstore: allocate compression during late_initcall > > ramoop's pstore registration (using pstore_register) has to run during > late_initcall because crypto backend may not be ready during > postcore_initcall. This causes missing of dmesg crash dumps which could > have been caught by pstore. > > Instead, lets allow ramoops pstore registration earlier, and once crypto > is ready we can initialize the compression. > > Reported-by: Sai Prakash Ranjan > Signed-off-by: Joel Fernandes (Google) > --- > fs/pstore/platform.c | 13 +++++++++++++ > fs/pstore/ram.c | 2 +- > 2 files changed, 14 insertions(+), 1 deletion(-) > > diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c > index 15e99d5a681d..f09066db2d4d 100644 > --- a/fs/pstore/platform.c > +++ b/fs/pstore/platform.c > @@ -780,6 +780,19 @@ void __init pstore_choose_compression(void) > } > } > > +static int __init pstore_compression_late_init(void) > +{ > + /* > + * Check if any pstore backends registered earlier but did not allocate > + * for compression because crypto was not ready, if so then initialize > + * compression. > + */ > + if (psinfo && !tfm) > + allocate_buf_for_compression(); > + return 0; > +} > +late_initcall(pstore_compression_late_init); > + > module_param(compress, charp, 0444); > MODULE_PARM_DESC(compress, "Pstore compression to use"); > > diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c > index bbd1e357c23d..98e48d1a9776 100644 > --- a/fs/pstore/ram.c > +++ b/fs/pstore/ram.c > @@ -940,7 +940,7 @@ static int __init ramoops_init(void) > ramoops_register_dummy(); > return platform_driver_register(&ramoops_driver); > } > -late_initcall(ramoops_init); > +postcore_initcall(ramoops_init); > > static void __exit ramoops_exit(void) > { > Yes I could see the early crash dump. Also I tested with different compression (LZO) instead of deflate just to be sure and it works fine, thanks :) Tested-by: Sai Prakash Ranjan -- QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation