On 2011-02-28 10:51, Vivek Goyal wrote: > o Dominik Klein reported a system hang issue while doing some blkio throttling > testing. > > https://lkml.org/lkml/2011/2/24/173 > > o Some tracing revealed that CFQ was not dispatching any more jobs as queue > unplug was not happening. And queue unplug was not happening because unplug > work was not being called as there was one throttling work on same cpu > which as not finished yet. And throttling work had not finished as it > was tyring to dispatch a bio to CFQ but all the request descriptors were > consume to it was put to sleep. > > o So basically it is a cyclic dependecny between CFQ unplug work and throtl > dispatch work. Tejun suggested that use separate workqueue for such cases.. > > o This patch uses a separate workqueue for throttle related work and does not > rely on kblockd workqueue anymore.
Not good, that's definitely a bug. I'll queue this up for 2.6.38. -- Jens Axboe _______________________________________________ stable mailing list [email protected] http://linux.kernel.org/mailman/listinfo/stable
