Messages in this thread | | | Date | Mon, 24 Mar 2008 15:31:45 +0100 | From | Marcin Slusarz <> | Subject | Re: [PATCH 0/2] printk vs rq->lock and xtime lock |
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On Mon, Mar 24, 2008 at 01:24:24PM +0100, Peter Zijlstra wrote: > Hi Linus, > > As to the regression reported by Marcin; what happens is that we invoke > printk() while holding the xtime lock for writing. printk() will call > wake_up_klogd() which tries to enqueue klogd on some rq. > > The known deadlock here is calling printk() while holding rq->lock, which > would then try to recusively lock the rq again when trying to wake klogd. > > The new deadlock is due to task enqueues setting an hrtimer, which requires > reading the time, which will result in a live-lock when the printk() call- > site is holding the xtime lock for writing. > > Thomas would like to preserve the printk() information if possible, hence my > proposal of printk_nowakeup(). It will do everything printk() normally does, > except ommit to wake up of klogd. The call is explicitly not EXPORTed so that > its use is confined to core kernel code. > > Marcin, could you please test these two patches to confirm they do indeed > solve your issue as well?
I've successfully tested these patches. Thanks. Tested-by: Marcin Slusarz <marcin.slusarz@gmail.com>
Marcin
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