A small patch to discuss, it's about killing an process in an out-of-memory
condition. First from the code I don't see any prohibition that it kills
init, if reaches maximum badness points, don't think thats something anybody
anytime wants. Sure for desktop systems this very unlikely to ever occur, but
for small embedded systems that could happen.
Second proposal is to give processes that are direct childs from init a
special bonus, normally that are those we don't want to get killed. They are
either important or get respawned eitherway creating an endless oom condition
loop when killing them.
A position to think about is to generally bonus processes from their distance
to init. The further down in the hirachy to more unlikely it is for the
process to be important.
Greetings, Axel
diff -ru linux-2.4.20-org/mm/oom_kill.c linux-2.4.20/mm/oom_kill.c
--- linux-2.4.20-org/mm/oom_kill.c Fri Nov 29 00:53:15 2002
+++ linux-2.4.20/mm/oom_kill.c Tue Feb 4 12:10:40 2003
@@ -62,6 +62,11 @@
if (!p->mm)
return 0;
/*
+ * Never kill init
+ */
+ if (p->pid == 1)
+ return 0:
+ /*
* The memory size of the process is the basis for the badness.
*/
points = p->mm->total_vm;
@@ -101,6 +106,15 @@
*/
if (cap_t(p->cap_effective) & CAP_TO_MASK(CAP_SYS_RAWIO))
points /= 4;
+
+ /*
+ * Give childs from init a bonus, they usually get respawned
+ * eitherway, killing them might not help to solve the out of memory
+ * condition in the long run.
+ */
+ if (p->p_pptr != NULL && p->p_pptr->pid == 1)
+ points /= 4;
+
#ifdef DEBUG
printk(KERN_DEBUG "OOMkill: task %d (%s) got %d points\n",
p->pid, p->comm, points);
On Tuesday 04 February 2003 06:32 am, Axel Kittenberger wrote:
> A small patch to discuss, it's about killing an process in an out-of-memory
> condition. First from the code I don't see any prohibition that it kills
> init, if reaches maximum badness points, don't think thats something
> anybody anytime wants. Sure for desktop systems this very unlikely to ever
> occur, but for small embedded systems that could happen.
ok.
> Second proposal is to give processes that are direct childs from init a
> special bonus, normally that are those we don't want to get killed. They
> are either important or get respawned eitherway creating an endless oom
> condition loop when killing them.
And what about processes that get reparented to init? These could be causing
the OOM. I didn't think that the p_ptr was null when reparenting happens.
--
-------------------------------------------------------------------------
Jesse I Pollard, II
Email: [email protected]
Any opinions expressed are solely my own.
> And what about processes that get reparented to init? These could be
> causing the OOM. I didn't think that the p_ptr was null when reparenting
> happens.
Okay good, should we use the "original parent" instead?
Yes, I'm not absolutly not sure if the != NULL expression is necessary, Don't
know enough about the task structering for this. I tried without and the
machine at least didn't crash, but just wanted to be safe.
On Tuesday 04 February 2003 08:13 am, Axel Kittenberger wrote:
> > And what about processes that get reparented to init? These could be
> > causing the OOM. I didn't think that the p_ptr was null when reparenting
> > happens.
>
> Okay good, should we use the "original parent" instead?
I'm not familiar enough with the reparenting to know. I'm not sure you can
tell the difference.
> Yes, I'm not absolutly not sure if the != NULL expression is necessary,
> Don't know enough about the task structering for this. I tried without and
> the machine at least didn't crash, but just wanted to be safe.
I was considering that a possible test for a reparented process since the
original parent doesn't necessarily exist anymore, though it would make
more sense to have that point to init, than point to anything else.
--
-------------------------------------------------------------------------
Jesse I Pollard, II
Email: [email protected]
Any opinions expressed are solely my own.