Hi all, On 22.02.2011 02:43, Dave Hylands wrote:
Hi guys, There is a bug in the kernel workqueues. I observed it in 2.6.36.3 (it seems to have been introduced in 2.6.36 and is still in 2.6.37.1), One of my colleagues was investigating and contacted the author of the workqueue code (Tejun Heo). Tejun sent us the following patch: diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 11869fa..90a17ca 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -2047,6 +2047,15 @@ repeat: move_linked_works(work, scheduled,&n); process_scheduled_works(rescuer); + + /* + * Leave this gcwq. If keep_working() is %true, notify a + * regular worker; otherwise, we end up with 0 concurrency + * and stalling the execution. + */ + if (keep_working(gcwq)) + wake_up_worker(gcwq); + spin_unlock_irq(&gcwq->lock); } For us, this was causing card insertion events to not be processed. For us it was a race condition and depended on when the timer tick occured in relation to other processing, and since you're talking about PREEMPTION making a difference, I thought I would throw this out as maybe being relevant. Dave Hylands
unfortunately the cards didn't work with the patch. We tried updating from 2.6.37-rc8 to 2.6.38-rc5 and the timeout error still occurs. However the cards get detected after the error and seem to work fine: [ 2.456512] Waiting for root device /dev/mmcblk0p2... [ 4.803375] mmc0: error -110 whilst initialising SD card [ 5.201019] mmc0: new SD card at address aaaa [ 5.206665] mmcblk0: mmc0:aaaa SU02G 1.84 GiB [ 5.214477] mmcblk0: p1 p2 Regards, Johannes -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
