Commit 05f54c13 authored by Committed by Linus Torvalds
Revert "kobject: don't block for each kobject_uevent".
This reverts commit f520360d. 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. An alternative would be to keep the UMH_NO_WAIT, and complicate the code to allocate and free these resources correctly? but 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. Reported-by: Tetsuo Handa <email@example.com> Signed-off-by: Hugh Dickins <firstname.lastname@example.org> Acked-by: Greg Kroah-Hartman <email@example.com> Acked-by: Arjan van de Ven <firstname.lastname@example.org> Acked-by: Will Newton <email@example.com> Signed-off-by: Linus Torvalds <firstname.lastname@example.org>
Showing with 1 addition and 1 deletion