On 12/06/2012 07:42 AM, Oleg Nesterov wrote:
Hi,
(add lkml)
On 12/06, Ben Hutchings wrote:
On Wed, 2012-12-05 at 14:13 -0500, Joseph Salisbury wrote:
Hi Oleg,
A bug was opened against the Ubuntu kernel[0]. It was found that
reverting commit b40a79591ca918e7b91b0d9b6abd5d00f2e88c19 resolved this
bug, and allowed suspend/resume to work properly.
I see that you are the author of this patch, so I wanted to run it by
you. I was thinking of requesting a revert for 3.2 stable, but I wanted
to get your feedback first.
Thanks,
Joe
[0] https://bugs.launchpad.net/ubuntu/+source/v86d/+bug/1080530
If I understand this rightly:
1. Suspend is aborted because the v86d usermodehelper cannot be frozen.
2. Before this fix, usermodehelpers could inherit PF_NOFREEZE (what
could possibly go wrong with that?!), which is why this didn't
previously happen.
Yes, try_to_freeze_tasks() ignores PF_NOFREEZE tasks
3. However, usermodehelpers are supposed to be disabled while the
freezer is running. Why is this one still running?
__usermodehelper_disable() doesn't try to kill/stop/whatever the already
spawned tasks...
The question is, why v86d refuses to freeze? It sleeps in TASK_INTERRUPTIBLE.
Oh... I seem to understand. This is 3.2 kernel, it also has PF_FREEZER_NOSIG.
which should be cleared along with PF_NOFREEZE.
This flag was removed upstream, but the older kernel need the fix. Could
you test the patch below?
Oleg.
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1084,7 +1084,7 @@ int flush_old_exec(struct linux_binprm *
set_fs(USER_DS);
current->flags &=
- ~(PF_RANDOMIZE | PF_FORKNOEXEC | PF_KTHREAD | PF_NOFREEZE);
+ ~(PF_RANDOMIZE | PF_FORKNOEXEC | PF_KTHREAD | PF_NOFREEZE |
PF_FREEZER_NOSIG);
flush_thread();
current->personality &= ~bprm->per_clear;
Hi Oleg,
A couple of people have tested your patch and report if fixes the
suspend/resume bug[0]. Thanks for the quick fix! Will you be
requesting this patch in the stable kernels?
Thanks again,
Joe
[0] https://bugs.launchpad.net/bugs/1080530
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