forked from luck/tmp_suning_uos_patched
88db5e1489
HP nx6125/nx6325/... machines have a _GPE handler with an infinite loop sending Notify() events to different ACPI subsystems. Notify handler in ACPI driver is a C-routine, which may call ACPI interpreter again to get access to some ACPI variables (acpi_evaluate_xxx). On these HP machines such an evaluation changes state of some variable and lets the loop above break. In the current ACPI implementation Notify requests are being deferred to the same kacpid workqueue on which the above GPE handler with infinite loop is executing. Thus we have a deadlock -- loop will continue to spin, sending notify events, and at the same time preventing these notify events from being run on a workqueue. All notify events are deferred, thus we see increase in memory consumption noticed by author of the thread. Also as GPE handling is bloked, machines overheat. Eventually by external poll of the same acpi_evaluate, kacpid is released and all the queued notify events are free to run, thus 100% cpu utilization by kacpid for several seconds or more. To prevent all these horrors it's needed to not put notify events to kacpid workqueue by either executing them immediately or putting them on some other thread. It's dangerous to execute notify events in place, as it will put several ACPI interpreter stacks on top of each other (at least 4 in case of nx6125), thus causing kernel stack overflow. First attempt to create a new thread was done by Peter Wainwright He created a bunch of threads, which were stealing work from a kacpid workqueue. This patch appeared in 2.6.15 kernel shipped with Ubuntu 6.06 LTS. Second attempt was done by me, I created a new thread for each Notify event. This worked OK on HP nx machines, but broke Linus' Compaq n620c, by producing threads with a speed what they stopped the machine completely. Thus this patch was reverted from 18-rc2 as I remember. I re-made the patch to create second workqueue just for notify events, thus hopping it will not break Linus' machine. Patch was tested on the same HP nx machines in #5534 and #7122, but I did not received reply from Linus on a test patch sent to him. Patch went to 19-rc and was rejected with much fanfare again. There was 4th patch, which inserted schedule_timeout(1) into deferred execution of kacpid, if we had any notify requests pending, but Linus decided that it was too complex (involved either changes to workqueue to see if it's empty or atomic inc/dec). Now you see last variant which adds yield() to every GPE execution. http://bugzilla.kernel.org/show_bug.cgi?id=5534 http://bugzilla.kernel.org/show_bug.cgi?id=8385 Signed-off-by: Alexey Starikovskiy <alexey.y.starikovskiy@intel.com> Signed-off-by: Len Brown <len.brown@intel.com> |
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| acorn | ||
| acpi | ||
| amba | ||
| ata | ||
| atm | ||
| auxdisplay | ||
| base | ||
| block | ||
| bluetooth | ||
| cdrom | ||
| char | ||
| clocksource | ||
| connector | ||
| cpufreq | ||
| crypto | ||
| dio | ||
| dma | ||
| edac | ||
| eisa | ||
| fc4 | ||
| firmware | ||
| hid | ||
| hwmon | ||
| i2c | ||
| ide | ||
| ieee1394 | ||
| infiniband | ||
| input | ||
| isdn | ||
| kvm | ||
| leds | ||
| macintosh | ||
| mca | ||
| md | ||
| media | ||
| message | ||
| mfd | ||
| misc | ||
| mmc | ||
| mtd | ||
| net | ||
| nubus | ||
| oprofile | ||
| parisc | ||
| parport | ||
| pci | ||
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| pnp | ||
| ps3 | ||
| rapidio | ||
| rtc | ||
| s390 | ||
| sbus | ||
| scsi | ||
| serial | ||
| sh | ||
| sn | ||
| spi | ||
| tc | ||
| telephony | ||
| usb | ||
| video | ||
| w1 | ||
| zorro | ||
| Kconfig | ||
| Makefile | ||