Commit 01315922 authored by Dave Peterson's avatar Dave Peterson Committed by Linus Torvalds
Browse files

[PATCH] mm: fix mm_struct reference counting bugs in mm/oom_kill.c



Fix oom_kill_task() so it doesn't call mmput() (which may sleep) while
holding tasklist_lock.
Signed-off-by: default avatarDavid S. Peterson <dsp@llnl.gov>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 97c2c9b8
......@@ -254,17 +254,24 @@ static void __oom_kill_task(task_t *p, const char *message)
force_sig(SIGKILL, p);
}
static struct mm_struct *oom_kill_task(task_t *p, const char *message)
static int oom_kill_task(task_t *p, const char *message)
{
struct mm_struct *mm = get_task_mm(p);
struct mm_struct *mm;
task_t * g, * q;
if (!mm)
return NULL;
if (mm == &init_mm) {
mmput(mm);
return NULL;
}
mm = p->mm;
/* 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 || mm == &init_mm)
return 1;
__oom_kill_task(p, message);
/*
......@@ -276,13 +283,12 @@ static struct mm_struct *oom_kill_task(task_t *p, const char *message)
__oom_kill_task(q, message);
while_each_thread(g, q);
return mm;
return 0;
}
static struct mm_struct *oom_kill_process(struct task_struct *p,
unsigned long points, const char *message)
static int oom_kill_process(struct task_struct *p, unsigned long points,
const char *message)
{
struct mm_struct *mm;
struct task_struct *c;
struct list_head *tsk;
......@@ -293,9 +299,8 @@ static struct mm_struct *oom_kill_process(struct task_struct *p,
c = list_entry(tsk, struct task_struct, sibling);
if (c->mm == p->mm)
continue;
mm = oom_kill_task(c, message);
if (mm)
return mm;
if (!oom_kill_task(c, message))
return 0;
}
return oom_kill_task(p, message);
}
......@@ -310,7 +315,6 @@ static struct mm_struct *oom_kill_process(struct task_struct *p,
*/
void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask, int order)
{
struct mm_struct *mm = NULL;
task_t *p;
unsigned long points = 0;
......@@ -330,12 +334,12 @@ void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask, int order)
*/
switch (constrained_alloc(zonelist, gfp_mask)) {
case CONSTRAINT_MEMORY_POLICY:
mm = oom_kill_process(current, points,
oom_kill_process(current, points,
"No available memory (MPOL_BIND)");
break;
case CONSTRAINT_CPUSET:
mm = oom_kill_process(current, points,
oom_kill_process(current, points,
"No available memory in cpuset");
break;
......@@ -357,8 +361,7 @@ retry:
panic("Out of memory and no killable processes...\n");
}
mm = oom_kill_process(p, points, "Out of memory");
if (!mm)
if (oom_kill_process(p, points, "Out of memory"))
goto retry;
break;
......@@ -367,8 +370,6 @@ retry:
out:
read_unlock(&tasklist_lock);
cpuset_unlock();
if (mm)
mmput(mm);
/*
* Give "p" a good chance of killing itself before we
......
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