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mm: revert "oom: move oom_adj value"

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The commit 2ff05b2b (oom: move oom_adj value) moveed the oom_adj value to
the mm_struct.  It was a very good first step for sanitize OOM.

However Paul Menage reported the commit makes regression to his job
scheduler.  Current OOM logic can kill OOM_DISABLED process.

Why? His program has the code of similar to the following.

	...
	set_oom_adj(OOM_DISABLE); /* The job scheduler never killed by oom */
	...
	if (vfork() == 0) {
		set_oom_adj(0); /* Invoked child can be killed */
		execve("foo-bar-cmd");
	}
	....

vfork() parent and child are shared the same mm_struct.  then above
set_oom_adj(0) doesn't only change oom_adj for vfork() child, it's also
change oom_adj for vfork() parent.  Then, vfork() parent (job scheduler)
lost OOM immune and it was killed.

Actually, fork-setting-exec idiom is very frequently used in userland program.
We must not break this assumption.

Then, this patch revert commit 2ff05b2b and related commit.

Reverted commit list
---------------------
- commit 2ff05b2b4e (oom: move oom_adj value from task_struct to mm_struct)
- commit 4d8b9135c3 (oom: avoid unnecessary mm locking and scanning for OOM_DISABLE)
- commit 8123681022 (oom: only oom kill exiting tasks with attached memory)
- commit 933b787b57 (mm: copy over oom_adj value at fork time)

Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Paul Menage <menage@google.com>
Cc: David Rientjes <rientjes@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Nick Piggin <npiggin@suse.de>
Cc: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
KOSAKI Motohiro
2009-08-18 14:11:10 -07:00
committed by Linus Torvalds
parent 89a4eb4b66
commit 0753ba01e1
6 changed files with 48 additions and 54 deletions
Download Patch File Download Diff File Expand all files Collapse all files

64
mm/oom_kill.c
View File

@ -58,7 +58,6 @@ unsigned long badness(struct task_struct *p, unsigned long uptime)
unsigned long points, cpu_time, run_time;
struct mm_struct *mm;
struct task_struct *child;
int oom_adj;
task_lock(p);
mm = p->mm;
@ -66,11 +65,6 @@ unsigned long badness(struct task_struct *p, unsigned long uptime)
task_unlock(p);
return 0;
}
oom_adj = mm->oom_adj;
if (oom_adj == OOM_DISABLE) {
task_unlock(p);
return 0;
}
/*
* The memory size of the process is the basis for the badness.
@ -154,15 +148,15 @@ unsigned long badness(struct task_struct *p, unsigned long uptime)
points /= 8;
/*
* Adjust the score by oom_adj.
* Adjust the score by oomkilladj.
*/
if (oom_adj) {
if (oom_adj > 0) {
if (p->oomkilladj) {
if (p->oomkilladj > 0) {
if (!points)
points = 1;
points <<= oom_adj;
points <<= p->oomkilladj;
} else
points >>= -(oom_adj);
points >>= -(p->oomkilladj);
}
#ifdef DEBUG
@ -257,8 +251,11 @@ static struct task_struct *select_bad_process(unsigned long *ppoints,
*ppoints = ULONG_MAX;
}
if (p->oomkilladj == OOM_DISABLE)
continue;
points = badness(p, uptime.tv_sec);
if (points > *ppoints) {
if (points > *ppoints || !chosen) {
chosen = p;
*ppoints = points;
}
@ -307,7 +304,8 @@ static void dump_tasks(const struct mem_cgroup *mem)
}
printk(KERN_INFO "[%5d] %5d %5d %8lu %8lu %3d %3d %s\n",
p->pid, __task_cred(p)->uid, p->tgid, mm->total_vm,
get_mm_rss(mm), (int)task_cpu(p), mm->oom_adj, p->comm);
get_mm_rss(mm), (int)task_cpu(p), p->oomkilladj,
p->comm);
task_unlock(p);
} while_each_thread(g, p);
}
@ -325,8 +323,11 @@ static void __oom_kill_task(struct task_struct *p, int verbose)
return;
}
if (!p->mm)
if (!p->mm) {
WARN_ON(1);
printk(KERN_WARNING "tried to kill an mm-less task!\n");
return;
}
if (verbose)
printk(KERN_ERR "Killed process %d (%s)\n",
@ -348,13 +349,28 @@ static int oom_kill_task(struct task_struct *p)
struct mm_struct *mm;
struct task_struct *g, *q;
task_lock(p);
mm = p->mm;
if (!mm || mm->oom_adj == OOM_DISABLE) {
task_unlock(p);
/* WARNING: mm may not be dereferenced since we did not obtain its
* value from get_task_mm(p). This is OK since all we need to do is
* compare mm to q->mm below.
*
* Furthermore, even if mm contains a non-NULL value, p->mm may
* change to NULL at any time since we do not hold task_lock(p).
* However, this is of no concern to us.
*/
if (mm == NULL)
return 1;
}
task_unlock(p);
/*
* Don't kill the process if any threads are set to OOM_DISABLE
*/
do_each_thread(g, q) {
if (q->mm == mm && q->oomkilladj == OOM_DISABLE)
return 1;
} while_each_thread(g, q);
__oom_kill_task(p, 1);
/*
@ -377,11 +393,10 @@ static int oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
struct task_struct *c;
if (printk_ratelimit()) {
task_lock(current);
printk(KERN_WARNING "%s invoked oom-killer: "
"gfp_mask=0x%x, order=%d, oom_adj=%d\n",
current->comm, gfp_mask, order,
current->mm ? current->mm->oom_adj : OOM_DISABLE);
"gfp_mask=0x%x, order=%d, oomkilladj=%d\n",
current->comm, gfp_mask, order, current->oomkilladj);
task_lock(current);
cpuset_print_task_mems_allowed(current);
task_unlock(current);
dump_stack();
@ -394,9 +409,8 @@ static int oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
/*
* If the task is already exiting, don't alarm the sysadmin or kill
* its children or threads, just set TIF_MEMDIE so it can die quickly
* if its mm is still attached.
*/
if (p->mm && (p->flags & PF_EXITING)) {
if (p->flags & PF_EXITING) {
__oom_kill_task(p, 0);
return 0;
}