Messages in this thread | | | Date | Thu, 16 Apr 2009 22:36:52 +0100 | Subject | Re: Please revert kobject_uevent UMH_NO_WAIT | From | Will Newton <> |
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On Thu, Apr 16, 2009 at 10:30 PM, Arjan van de Ven <arjan@linux.intel.com> wrote: > Greg KH wrote: >> >> On Thu, Apr 16, 2009 at 09:55:29PM +0100, Hugh Dickins wrote: >>> >>> Please revert commit f520360d93cdc37de5d972dac4bf3bdef6a7f6a7 >>> "kobject: don't block for each kobject_uevent". >>> >>> Tetsuo Handa, running a kernel with CONFIG_DEBUG_PAGEALLOC=y >>> and CONFIG_UEVENT_HELPER_PATH=/sbin/hotplug, has been hitting RCU >>> detected CPU stalls: it's been spinning in the loop where do_execve() >>> counts up the args (but why wasn't fixup_exception working? dunno). >>> >>> The recent change, switching kobject_uevent_env() from UMH_WAIT_EXEC >>> to UMH_NO_WAIT, is broken: the exec uses args on the local stack here, >>> and an env which is kfreed as soon as call_usermodehelper() returns. >>> It very much needs to wait for the exec to be done. >>> >>> Or keep the UMH_NO_WAIT, and complicate the code to allocate and free >>> these resources correctly? No, as GregKH pointed out when making the >>> commit, CONFIG_UEVENT_HELPER_PATH="" is a much better optimization - >>> though some distros are still saying /sbin/hotplug in their .config, >>> yet with no such binary in their initrd or their root. >>> >>> Or... >>> >>> [PATCH] revert kobject_uevent UMH_NO_WAIT >>> >>> Reported-by: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp> >>> Signed-off-by: Hugh Dickins <hugh@veritas.com> >> >> Acked-by: Greg Kroah-Hartman <gregkh@suse.de> > > Acked-by: Arjan van de Ven <arjan@linux.intel.com> > as well > > not worth the hassle if this breaks too much
Acked-by: Will Newton <will.newton@gmail.com>
It's causing crashes for me too (reported 10 days ago).
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