http://bugzilla.kernel.org/show_bug.cgi?id=13493 --- Comment #6 from Márton Németh <nm127@xxxxxxxxxxx> 2009-06-12 04:19:58 --- Created an attachment (id=21864) --> (http://bugzilla.kernel.org/attachment.cgi?id=21864) git bisect log I bisected this problem on an EeePC 901. The result is: b14893a62c73af0eca414cfed505b8c09efc613c is first bad commit commit b14893a62c73af0eca414cfed505b8c09efc613c Author: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxx> Date: Sun May 17 10:30:45 2009 -0400 [CPUFREQ] fix timer teardown in ondemand governor * Rafael J. Wysocki (rjw@xxxxxxx) wrote: > This message has been generated automatically as a part of a report > of regressions introduced between 2.6.28 and 2.6.29. > > The following bug entry is on the current list of known regressions > introduced between 2.6.28 and 2.6.29. Please verify if it still should > be listed and let me know (either way). > > > Bug-Entry : http://bugzilla.kernel.org/show_bug.cgi?id=13186 > Subject : cpufreq timer teardown problem > Submitter : Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxx> > Date : 2009-04-23 14:00 (24 days old) > References : http://marc.info/?l=linux-kernel&m=124049523515036&w=4 > Handled-By : Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxx> > Patch : http://patchwork.kernel.org/patch/19754/ > http://patchwork.kernel.org/patch/19753/ > (updated changelog) cpufreq fix timer teardown in ondemand governor The problem is that dbs_timer_exit() uses cancel_delayed_work() when it should use cancel_delayed_work_sync(). cancel_delayed_work() does not wait for the workqueue handler to exit. The ondemand governor does not seem to be affected because the "if (!dbs_info->enable)" check at the beginning of the workqueue handler returns immediately without rescheduling the work. The conservative governor in 2.6.30-rc has the same check as the ondemand governor, which makes things usually run smoothly. However, if the governor is quickly stopped and then started, this could lead to the following race : dbs_enable could be reenabled and multiple do_dbs_timer handlers would run. This is why a synchronized teardown is required. The following patch applies to, at least, 2.6.28.x, 2.6.29.1, 2.6.30-rc2. Depends on patch cpufreq: remove rwsem lock from CPUFREQ_GOV_STOP call Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxx> CC: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> CC: gregkh@xxxxxxx CC: stable@xxxxxxxxxx CC: cpufreq@xxxxxxxxxxxxxxx CC: Ingo Molnar <mingo@xxxxxxx> CC: rjw@xxxxxxx CC: Ben Slusky <sluskyb@xxxxxxxxxxxxxx> Signed-off-by: Dave Jones <davej@xxxxxxxxxx> :040000 040000 d7fb0f04e2d13be36ff8a5fba2e6bbcff4406996 482e48e8a15065bf48e28a98db06433ced382551 M drivers -- Configure bugmail: http://bugzilla.kernel.org/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are the assignee for the bug.-- To unsubscribe from this list: send the line "unsubscribe cpufreq" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
