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| author | Hugh Dickins <hugh@veritas.com> | 2009-04-16 22:55:29 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-04-16 23:41:24 +0200 |
| commit | 05f54c13cd0c33694eec39a265475c5d6cf223cf (patch) | |
| tree | f3bdff25fd2e7f405ec159bdabd9ef1166d1f22d /lib | |
| parent | Add block_write_full_page_endio for passing endio handler (diff) | |
| download | linux-05f54c13cd0c33694eec39a265475c5d6cf223cf.tar.xz linux-05f54c13cd0c33694eec39a265475c5d6cf223cf.zip | |
Revert "kobject: don't block for each kobject_uevent".
This reverts commit f520360d93cdc37de5d972dac4bf3bdef6a7f6a7.
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 <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>
Acked-by: Will Newton <will.newton@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/kobject_uevent.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/lib/kobject_uevent.c b/lib/kobject_uevent.c index 97a777ad4f59..dafeecf5b143 100644 --- a/lib/kobject_uevent.c +++ b/lib/kobject_uevent.c @@ -258,7 +258,7 @@ int kobject_uevent_env(struct kobject *kobj, enum kobject_action action, goto exit; retval = call_usermodehelper(argv[0], argv, - env->envp, UMH_NO_WAIT); + env->envp, UMH_WAIT_EXEC); } exit: |