Messages in this thread | | | Date | Thu, 06 Dec 2012 15:44:01 -0500 | From | Joseph Salisbury <> | Subject | Re: freezer: exec should clear PF_NOFREEZE along with PF_KTHREAD |
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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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