On Wed, 2010-02-17 at 01:36 -0800, David Rientjes wrote: > On Wed, 17 Feb 2010, Minchan Kim wrote: > > > diff --git a/mm/oom_kill.c b/mm/oom_kill.c > > index 3618be3..d5e3d70 100644 > > --- a/mm/oom_kill.c > > +++ b/mm/oom_kill.c > > @@ -32,6 +32,8 @@ int sysctl_panic_on_oom; > > int sysctl_oom_kill_allocating_task; > > int sysctl_oom_dump_tasks; > > static DEFINE_SPINLOCK(zone_scan_lock); > > + > > +unsigned int nr_memdie; /* count of TIF_MEMDIE processes */ > > /* #define DEBUG */ > > > > /* > > @@ -295,6 +297,8 @@ static struct task_struct > > *select_bad_process(unsigned long *ppoints, > > > > chosen = p; > > *ppoints = ULONG_MAX; > > + if (nr_memdie == 0) > > + break; > > } > > > > if (p->signal->oom_adj == OOM_DISABLE) > > Nack, finding a candidate task with TIF_MEMDIE set is not the only time we > return ERR_PTR(-1UL) from select_bad_process(): we also do it if any other > task other than current is PF_EXITING. Thus, we _must_ continue the > tasklist scan to avoid needlessly killing current simply because it was > the first PF_EXITING task in the tasklist. Okay. Sorry for missing PF_EXITING tasks. > > > @@ -403,8 +407,6 @@ static void __oom_kill_task(struct task_struct *p, > > int verbose) > > K(p->mm->total_vm), > > K(get_mm_counter(p->mm, MM_ANONPAGES)), > > K(get_mm_counter(p->mm, MM_FILEPAGES))); > > - task_unlock(p); > > - > > /* > > * We give our sacrificial lamb high priority and access to > > * all the memory it needs. That way it should be able to > > @@ -412,7 +414,11 @@ static void __oom_kill_task(struct task_struct > > *p, int verbose) > > */ > > p->rt.time_slice = HZ; > > set_tsk_thread_flag(p, TIF_MEMDIE); > > - > > + /* > > + * nr_memdie is protected by task_lock. > > + */ > > + nr_memdie++; > > + task_unlock(p); > > force_sig(SIGKILL, p); > > } > > > > task_lock() is a per-task entity, i.e. each task_struct has an alloc_lock > spinlock. This cannot protect a global variable. Yes. It was utterly dumb lock usage. Thanks for the quick reply. -- Kind regards, Minchan Kim -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>