提交 05f54c13 编写于 作者: H Hugh Dickins 提交者: 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: NTetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Signed-off-by: NHugh Dickins <hugh@veritas.com>
Acked-by: NGreg Kroah-Hartman <gregkh@suse.de>
Acked-by: NArjan van de Ven <arjan@linux.intel.com>
Acked-by: NWill Newton <will.newton@gmail.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
上级 35c80d5f
...@@ -258,7 +258,7 @@ int kobject_uevent_env(struct kobject *kobj, enum kobject_action action, ...@@ -258,7 +258,7 @@ int kobject_uevent_env(struct kobject *kobj, enum kobject_action action,
goto exit; goto exit;
retval = call_usermodehelper(argv[0], argv, retval = call_usermodehelper(argv[0], argv,
env->envp, UMH_NO_WAIT); env->envp, UMH_WAIT_EXEC);
} }
exit: exit:
......
Markdown is supported
0% .
You are about to add 0 people to the discussion. Proceed with caution.
先完成此消息的编辑!
想要评论请 注册