| Message ID | 20141021141159.GE9415@dhcp22.suse.cz (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
On Tuesday, October 21, 2014 04:11:59 PM Michal Hocko wrote: > On Tue 21-10-14 15:42:23, Rafael J. Wysocki wrote: > > On Tuesday, October 21, 2014 03:14:45 PM Michal Hocko wrote: > > > On Tue 21-10-14 14:09:27, Rafael J. Wysocki wrote: > > > [...] > > > > > @@ -131,12 +132,40 @@ int freeze_processes(void) > > > > > > > > > > printk("Freezing user space processes ... "); > > > > > pm_freezing = true; > > > > > + oom_kills_saved = oom_kills_count(); > > > > > error = try_to_freeze_tasks(true); > > > > > if (!error) { > > > > > - printk("done."); > > > > > __usermodehelper_set_disable_depth(UMH_DISABLED); > > > > > oom_killer_disable(); > > > > > + > > > > > + /* > > > > > + * There might have been an OOM kill while we were > > > > > + * freezing tasks and the killed task might be still > > > > > + * on the way out so we have to double check for race. > > > > > + */ > > > > > + if (oom_kills_count() != oom_kills_saved) { > > > > > + struct task_struct *g, *p; > > > > > + > > > > > + read_lock(&tasklist_lock); > > > > > + for_each_process_thread(g, p) { > > > > > + if (p == current || freezer_should_skip(p) || > > > > > + frozen(p)) > > > > > + continue; > > > > > + error = -EBUSY; > > > > > + goto out_loop; > > > > > + } > > > > > +out_loop: > > > > > > > > Well, it looks like this will work here too: > > > > > > > > for_each_process_thread(g, p) > > > > if (p != current && !frozen(p) && > > > > !freezer_should_skip(p)) { > > > > error = -EBUSY; > > > > break; > > > > } > > > > > > > > or I am helplessly misreading the code. > > > > > > break will not work because for_each_process_thread is a double loop. > > > > I see. In that case I'd do: > > > > for_each_process_thread(g, p) > > if (p != current && !frozen(p) && > > !freezer_should_skip(p)) { > > > > read_unlock(&tasklist_lock); > > > > __usermodehelper_set_disable_depth(UMH_ENABLED); > > printk("OOM in progress."); > > error = -EBUSY; > > goto done; > > } > > > > to avoid adding the new label that looks odd. > > OK, incremental diff on top. I will post the complete patch if you are > happier with this change Yes, I am. > --- > diff --git a/kernel/power/process.c b/kernel/power/process.c > index a397fa161d11..7a37cf3eb1a2 100644 > --- a/kernel/power/process.c > +++ b/kernel/power/process.c > @@ -108,6 +108,28 @@ static int try_to_freeze_tasks(bool user_only) > return todo ? -EBUSY : 0; > } > > +/* > + * Returns true if all freezable tasks (except for current) are frozen already > + */ > +static bool check_frozen_processes(void) > +{ > + struct task_struct *g, *p; > + bool ret = true; > + > + read_lock(&tasklist_lock); > + for_each_process_thread(g, p) { > + if (p != current && !freezer_should_skip(p) && > + !frozen(p)) { > + ret = false; > + goto done; > + } > + } > +done: > + read_unlock(&tasklist_lock); > + > + return ret; > +} > + > /** > * freeze_processes - Signal user space processes to enter the refrigerator. > * The current thread will not be frozen. The same process that calls > @@ -143,25 +165,12 @@ int freeze_processes(void) > * freezing tasks and the killed task might be still > * on the way out so we have to double check for race. > */ > - if (oom_kills_count() != oom_kills_saved) { > - struct task_struct *g, *p; > - > - read_lock(&tasklist_lock); > - for_each_process_thread(g, p) { > - if (p == current || freezer_should_skip(p) || > - frozen(p)) > - continue; > - error = -EBUSY; > - goto out_loop; > - } > -out_loop: > - read_unlock(&tasklist_lock); > - > - if (error) { > - __usermodehelper_set_disable_depth(UMH_ENABLED); > - printk("OOM in progress."); > - goto done; > - } > + if (oom_kills_count() != oom_kills_saved && > + !check_frozen_processes()) { > + __usermodehelper_set_disable_depth(UMH_ENABLED); > + printk("OOM in progress."); > + error = -EBUSY; > + goto done; > } > printk("done."); > } >
diff --git a/kernel/power/process.c b/kernel/power/process.c index a397fa161d11..7a37cf3eb1a2 100644 --- a/kernel/power/process.c +++ b/kernel/power/process.c @@ -108,6 +108,28 @@ static int try_to_freeze_tasks(bool user_only) return todo ? -EBUSY : 0; } +/* + * Returns true if all freezable tasks (except for current) are frozen already + */ +static bool check_frozen_processes(void) +{ + struct task_struct *g, *p; + bool ret = true; + + read_lock(&tasklist_lock); + for_each_process_thread(g, p) { + if (p != current && !freezer_should_skip(p) && + !frozen(p)) { + ret = false; + goto done; + } + } +done: + read_unlock(&tasklist_lock); + + return ret; +} + /** * freeze_processes - Signal user space processes to enter the refrigerator. * The current thread will not be frozen. The same process that calls @@ -143,25 +165,12 @@ int freeze_processes(void) * freezing tasks and the killed task might be still * on the way out so we have to double check for race. */ - if (oom_kills_count() != oom_kills_saved) { - struct task_struct *g, *p; - - read_lock(&tasklist_lock); - for_each_process_thread(g, p) { - if (p == current || freezer_should_skip(p) || - frozen(p)) - continue; - error = -EBUSY; - goto out_loop; - } -out_loop: - read_unlock(&tasklist_lock); - - if (error) { - __usermodehelper_set_disable_depth(UMH_ENABLED); - printk("OOM in progress."); - goto done; - } + if (oom_kills_count() != oom_kills_saved && + !check_frozen_processes()) { + __usermodehelper_set_disable_depth(UMH_ENABLED); + printk("OOM in progress."); + error = -EBUSY; + goto done; } printk("done."); }