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[23.128.96.18]) by mx.google.com with ESMTP id w20si3976226pga.516.2021.10.20.09.01.58; Wed, 20 Oct 2021 09:02:19 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230501AbhJTQCc (ORCPT + 99 others); Wed, 20 Oct 2021 12:02:32 -0400 Received: from mail-ot1-f42.google.com ([209.85.210.42]:46841 "EHLO mail-ot1-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230372AbhJTQCa (ORCPT ); Wed, 20 Oct 2021 12:02:30 -0400 Received: by mail-ot1-f42.google.com with SMTP id x27-20020a9d459b000000b0055303520cc4so8740009ote.13; Wed, 20 Oct 2021 09:00:16 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=O8Vh3j/5jDTLXwbY1bkY5BeXtXCmKpCTYashNJhu/CY=; b=sEKjPHZ47Anvm+BR3aFCgVZ2/aQCq4YaOSKcKLgmXsDaVUFQlMSbe8EN2OA3O9afPa 0tus3qE2D4KDl/+wxWAnBcnIkZMqUkyqYXyxJZ5dFQJGODTvOQg6scc1ytKqBED+/u+t juNjIYsIPw+4AgvNyJOXX56JxW+umTxM1kqPcpbP3wNpwBbmE7BneqaW72scrwrvGgEs XUw/8pM/gtrkCzYxs30wCv7QpFl+4TImkLKcbg/PgtupcRd/BJp44O9pkLhymvTFJBfi z9kHfMuOGEpMW/vuxRNwyXH8vremtYhi5Coq3bvvquaSyCVMhfqfGTRFIvBBF8F7yHj2 v8Yg== X-Gm-Message-State: AOAM531OKgCXBbXkP1OXKL+Ioze78Qu4h/yBlSQ6or2S8pbTfKk6AQOX s78N+ouYoQxXiyKDtm8a5ervu/uEfj+pM09CKw8= X-Received: by 2002:a05:6830:90b:: with SMTP id v11mr53327ott.254.1634745615563; Wed, 20 Oct 2021 09:00:15 -0700 (PDT) MIME-Version: 1.0 References: <20211014075731.GB18719@xsang-OptiPlex-9020> <51c0a15f-1941-f161-dcec-a7a9acc726f2@gmail.com> <6755cf07-fa5a-cbb7-c076-57c162a08c99@gmail.com> <20aedfba-14e3-3677-d21a-b87610095445@gmail.com> <4300a3d4-76de-70c5-2a7b-c4d066ef5bc6@gmail.com> <8ebd1cad-fa35-8ad8-0be5-3dd3364196cb@gmail.com> In-Reply-To: <8ebd1cad-fa35-8ad8-0be5-3dd3364196cb@gmail.com> From: "Rafael J. Wysocki" Date: Wed, 20 Oct 2021 18:00:04 +0200 Message-ID: Subject: Re: [PM] bfcc1e67ff: kernel-selftests.breakpoints.step_after_suspend_test.fail To: Florian Fainelli Cc: "Rafael J. Wysocki" , "Rafael J. Wysocki" , LKML , Linux Memory Management List , lkp@lists.01.org, kbuild test robot , kernel test robot , Linux PM Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Oct 20, 2021 at 5:34 PM Florian Fainelli wrote: > > > > On 10/20/2021 6:49 AM, Rafael J. Wysocki wrote: > > On Tue, Oct 19, 2021 at 9:04 PM Florian Fainelli wrote: > >> > >> On 10/19/21 11:53 AM, Rafael J. Wysocki wrote: > >>> On 10/15/2021 9:40 PM, Florian Fainelli wrote: > >>>> On 10/15/21 11:45 AM, Rafael J. Wysocki wrote: > >>>>> On 10/14/2021 11:55 PM, Florian Fainelli wrote: > >>>>>> On 10/14/21 12:23 PM, Rafael J. Wysocki wrote: > >>>>>>> On 10/14/2021 6:26 PM, Florian Fainelli wrote: > >>>>>>>> On 10/14/21 12:57 AM, kernel test robot wrote: > >>>>>>>>> Greeting, > >>>>>>>>> > >>>>>>>>> FYI, we noticed the following commit (built with gcc-9): > >>>>>>>>> > >>>>>>>>> commit: bfcc1e67ff1e4aa8bfe2ca57f99390fc284c799d ("PM: sleep: Do not > >>>>>>>>> assume that "mem" is always present") > >>>>>>>>> https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git > >>>>>>>>> master > >>>>>>>>> > >>>>>>>>> > >>>>>>>>> in testcase: kernel-selftests > >>>>>>>>> version: kernel-selftests-x86_64-c8c9111a-1_20210929 > >>>>>>>>> with following parameters: > >>>>>>>>> > >>>>>>>>> group: group-00 > >>>>>>>>> ucode: 0x11 > >>>>>>>>> > >>>>>>>>> test-description: The kernel contains a set of "self tests" under > >>>>>>>>> the > >>>>>>>>> tools/testing/selftests/ directory. These are intended to be small > >>>>>>>>> unit tests to exercise individual code paths in the kernel. > >>>>>>>>> test-url: https://www.kernel.org/doc/Documentation/kselftest.txt > >>>>>>>>> > >>>>>>>>> > >>>>>>>>> on test machine: 288 threads 2 sockets Intel(R) Xeon Phi(TM) CPU > >>>>>>>>> 7295 > >>>>>>>>> @ 1.50GHz with 80G memory > >>>>>>>>> > >>>>>>>>> caused below changes (please refer to attached dmesg/kmsg for entire > >>>>>>>>> log/backtrace): > >>>>>>>>> > >>>>>>>>> > >>>>>>>>> > >>>>>>>>> > >>>>>>>>> If you fix the issue, kindly add following tag > >>>>>>>>> Reported-by: kernel test robot > >>>>>>>> Thanks for your report. Assuming that the code responsible for > >>>>>>>> registering the suspend operations is drivers/acpi/sleep.c for your > >>>>>>>> platform, and that acpi_sleep_suspend_setup() iterated over all > >>>>>>>> possible > >>>>>>>> sleep states, your platform must somehow be returning that > >>>>>>>> ACPI_STATE_S3 > >>>>>>>> is not a supported state somehow? > >>>>>>>> > >>>>>>>> Rafael have you ever encountered something like that? > >>>>>>> Yes, there are systems with ACPI that don't support S3. > >>>>>> OK and do you know what happens when we enter suspend with "mem" in > >>>>>> those cases? Do we immediately return because ultimately the firmware > >>>>>> does not support ACPI S3? > >>>>> "mem" should not be present in the list of available strings then, so it > >>>>> should be rejected right away. > >>>> Well yes, that was the purpose of the patch I submitted, but assuming > >>>> that we did provide "mem" as one of the possible standby modes even > >>>> though that was wrong (before patch), and the test was trying to enter > >>>> ACPI S3 standby, what would have happened, would the ACPI firmware honor > >>>> the request but return an error, or would it actually enter ACPI S3? > >>>> > >>>> In any case, I will change the test to check that this is a supported > >>>> standby mode before trying it. > >>> > >>> Unfortunately, I will need to revert bfcc1e67ff1e4aa8bfe2, because it > >>> breaks user space compatibility and that's got caught properly by the test. > >> > >> Reverting my commit will break powerpc and other ARM/ARM64 platforms > >> where mem is not supported (via PSCI), > > > > It won't break anything, although the things that didn't work before > > will still not work after it. > > > > And "mem" is always supported even if there are no suspend_ops at all, > > in which case it becomes an alternative way to trigger s2idle. > > > > So, on the affected systems, what's there in /sys/power/? Is > > mem_sleep present? If so, what's in it? > > With 4.9 which is what I used initially: > > # cat /sys/power/state > freeze standby > # cat /sys/power/ > pm_async pm_print_times pm_wakeup_irq wakeup_count > pm_freeze_timeout pm_test state > > With a newer kernel without my patch: > > # cat /sys/power/state > freeze standby mem > # cat /sys/power/mem_sleep > s2idle shallow [deep] OK, so the "deep" and "shallow" suspend variants appear to be supported. What's the problem with advertising "mem" then? > # cat /sys/power/ > mem_sleep pm_freeze_timeout pm_wakeup_irq wakeup_count > pm_async pm_print_times state > pm_debug_messages pm_test suspend_stats/ > > > > > >> I have a change pending for PSCI > >> that will actually check that SYSTEM_SUSPEND is supported before > >> unconditionally making use of it. > >> > >>> > >>> What happens is that "mem" is a "pointer" to a secondary list of > >>> possible states and that generally is "s2idle shallow deep" and if > >>> s2idle is the only available option, it will be just "s2idle". > >>> > >>> This list is there in /sys/power/mem_sleep. > >>> > >>> It was done this way, because some variants of user space expect "mem" > >>> to be always present and don't recognize "freeze" properly. > >>> > >>> Sorry for the confusion. > >> > >> So how do we all get our cookie here? Should we just slap an #ifndef > >> CONFIG_ACPI in order to allow platforms that do not have "mem" to not > >> have it? > > > > Certainly not. > > > > I've just hacked my test-bed system with ACPI so it does not register > > any suspend_ops at all and I have "freeze mem disk" in > > /sys/power/state and "s2idle" in /sys/power/mem_sleep. Writing "mem" > > to /sys/power/state causes s2idle to be carried out. > > > > Since this is the expected behavior, I'm not sure what the problem is. > > The problem is advertising "mem" in /sys/power/state when the state is > not actually supported by the platform firmware here, whether that > translates into the form of s2idle or not. It is not supported, and it > should not be there IMHO. Well, it is there, because some user space expects it to be there on systems supporting any kind of system-wide suspend, including s2idle. Like it or not. If it is not there, the utilities in question assume that system-wide suspend is not supported at all. >I was late to the game in identifying that, > but the 4.9 kernel makes sense to me. > > Similarly, if you take arch/powerpc/sysdev/fsl_pmc.c only > PM_SUSPEND_STANDBY is valid, so advertising mem would be wrong if we > don't look at what ->valid tells us. Again: "mem" appears in /sys/power/state if the system supports any kind of system-wide suspend (because of the expectations of user space mentioned above) and mem_sleep decides what it really means. And this is documented too (see Documentation/admin-guide/pm/sleep-states.html).