From: "Rafael J. Wysocki" <email@example.com> To: Sudeep Holla <firstname.lastname@example.org>, Viresh Kumar <email@example.com> Cc: "Rafael J. Wysocki" <firstname.lastname@example.org>, Linux PM <email@example.com>, Linux ACPI <firstname.lastname@example.org>, LKML <email@example.com>, Dmitry Osipenko <firstname.lastname@example.org> Subject: Re: [RFT][PATCH 0/3] cpufreq / PM: QoS: Introduce frequency QoS and use it in cpufreq Date: Thu, 17 Oct 2019 18:34:28 +0200 [thread overview] Message-ID: <CAJZ5v0ixS8ZS93Fgj8XGUMGcLdAy+Fgwp5z3QirccNSiiwLtDA@mail.gmail.com> (raw) In-Reply-To: <20191017095942.GF8978@bogus> On Thu, Oct 17, 2019 at 12:00 PM Sudeep Holla <email@example.com> wrote: > > On Thu, Oct 17, 2019 at 03:27:25PM +0530, Viresh Kumar wrote: > > On 16-10-19, 15:23, Sudeep Holla wrote: > > > Thanks for the spinning these patches so quickly. > > > > > > I did give it a spin, but unfortunately it doesn't fix the bug I reported. > > > So I looked at my bug report in detail and looks like the cpufreq_driver > > > variable is set to NULL at that point and it fails to dereference it > > > while trying to execute: > > > ret = cpufreq_driver->verify(new_policy); > > > (Hint verify is at offset 0x1c/28) > > > > > > So I suspect some race as this platform with bL switcher tries to > > > unregister and re-register the cpufreq driver during the boot. > > > > > > I need to spend more time on this as reverting the initial PM QoS patch > > > to cpufreq.c makes the issue disappear. I guess you mean commit 67d874c3b2c6 ("cpufreq: Register notifiers with the PM QoS framework")? That would make sense, because it added the cpufreq_notifier_min() and cpufreq_notifier_max() that trigger handle_update() via schedule_work(). [BTW, Viresh, it looks like cpufreq_set_policy() should still ensure that the new min is less than the new max, because the QoS doesn't do that.] > > Is this easily reproducible ? cpufreq_driver == NULL shouldn't be the case, it > > get updated only once while registering/unregistering cpufreq drivers. That is > > the last thing which can go wrong from my point of view :) > > > > Yes, if I boot my TC2 with bL switcher enabled, it always crashes on boot. It does look like handle_update() races with cpufreq_unregister_driver() and cpufreq_remove_dev (called from there indirectly) does look racy.
next prev parent reply other threads:[~2019-10-17 16:34 UTC|newest] Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-10-16 10:37 Rafael J. Wysocki 2019-10-16 10:41 ` [RFT][PATCH 1/3] PM: QoS: Introduce frequency QoS Rafael J. Wysocki 2019-10-17 9:41 ` Viresh Kumar 2019-10-17 14:16 ` Rafael J. Wysocki 2019-10-18 5:41 ` Viresh Kumar 2019-10-24 19:01 ` Leonard Crestez 2019-10-24 19:34 ` Leonard Crestez 2019-11-17 7:34 ` Doug Smythies 2019-11-17 16:13 ` Doug Smythies 2019-11-19 14:35 ` Doug Smythies 2019-11-19 19:17 ` Rafael J. Wysocki 2019-11-19 22:13 ` Rafael J. Wysocki 2019-11-20 6:55 ` Doug Smythies 2019-11-20 9:08 ` Rafael J. Wysocki 2019-10-16 10:47 ` [RFT][PATCH 2/3] cpufreq: Use per-policy " Rafael J. Wysocki 2019-10-16 18:01 ` Dmitry Osipenko 2019-10-17 21:29 ` Dmitry Osipenko 2019-10-18 9:29 ` Viresh Kumar 2019-10-18 15:31 ` Dmitry Osipenko 2019-10-16 10:47 ` [RFT][PATCH 3/3] PM: QoS: Drop frequency QoS types from device PM QoS Rafael J. Wysocki 2019-10-16 14:23 ` [RFT][PATCH 0/3] cpufreq / PM: QoS: Introduce frequency QoS and use it in cpufreq Sudeep Holla 2019-10-17 9:57 ` Viresh Kumar 2019-10-17 9:59 ` Sudeep Holla 2019-10-17 16:34 ` Rafael J. Wysocki [this message] 2019-10-17 16:42 ` Sudeep Holla 2019-10-18 5:44 ` Viresh Kumar 2019-10-18 8:24 ` Rafael J. Wysocki 2019-10-18 8:27 ` Viresh Kumar 2019-10-18 8:30 ` Rafael J. Wysocki 2019-10-18 9:24 ` Viresh Kumar 2019-10-18 9:26 ` Rafael J. Wysocki 2019-10-18 9:28 ` Viresh Kumar 2019-10-17 17:14 ` Sudeep Holla 2019-10-17 9:46 ` Viresh Kumar
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