Messages in this thread | | | Date | Thu, 16 Apr 2009 14:30:31 -0700 | From | Arjan van de Ven <> | Subject | Re: Please revert kobject_uevent UMH_NO_WAIT |
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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
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