android_kernel_xiaomi_sm8350/mm/oom_kill.c
David Rientjes 8123681022 oom: only oom kill exiting tasks with attached memory
When a task is chosen for oom kill and is found to be PF_EXITING,
__oom_kill_task() is called to elevate the task's timeslice and give it
access to memory reserves so that it may quickly exit.

This privilege is unnecessary, however, if the task has already detached
its mm.  Although its possible for the mm to become detached later since
task_lock() is not held, __oom_kill_task() will simply be a no-op in such
circumstances.

Subsequently, it is no longer necessary to warn about killing mm-less
tasks since it is a no-op.

Signed-off-by: David Rientjes <rientjes@google.com>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-06-16 19:47:45 -07:00

628 lines
16 KiB
C

/*
* linux/mm/oom_kill.c
*
* Copyright (C) 1998,2000 Rik van Riel
* Thanks go out to Claus Fischer for some serious inspiration and
* for goading me into coding this file...
*
* The routines in this file are used to kill a process when
* we're seriously out of memory. This gets called from __alloc_pages()
* in mm/page_alloc.c when we really run out of memory.
*
* Since we won't call these routines often (on a well-configured
* machine) this file will double as a 'coding guide' and a signpost
* for newbie kernel hackers. It features several pointers to major
* kernel subsystems and hints as to where to find out what things do.
*/
#include <linux/oom.h>
#include <linux/mm.h>
#include <linux/err.h>
#include <linux/sched.h>
#include <linux/swap.h>
#include <linux/timex.h>
#include <linux/jiffies.h>
#include <linux/cpuset.h>
#include <linux/module.h>
#include <linux/notifier.h>
#include <linux/memcontrol.h>
#include <linux/security.h>
int sysctl_panic_on_oom;
int sysctl_oom_kill_allocating_task;
int sysctl_oom_dump_tasks;
static DEFINE_SPINLOCK(zone_scan_lock);
/* #define DEBUG */
/**
* badness - calculate a numeric value for how bad this task has been
* @p: task struct of which task we should calculate
* @uptime: current uptime in seconds
*
* The formula used is relatively simple and documented inline in the
* function. The main rationale is that we want to select a good task
* to kill when we run out of memory.
*
* Good in this context means that:
* 1) we lose the minimum amount of work done
* 2) we recover a large amount of memory
* 3) we don't kill anything innocent of eating tons of memory
* 4) we want to kill the minimum amount of processes (one)
* 5) we try to kill the process the user expects us to kill, this
* algorithm has been meticulously tuned to meet the principle
* of least surprise ... (be careful when you change it)
*/
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;
if (!mm) {
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.
*/
points = mm->total_vm;
/*
* After this unlock we can no longer dereference local variable `mm'
*/
task_unlock(p);
/*
* swapoff can easily use up all memory, so kill those first.
*/
if (p->flags & PF_SWAPOFF)
return ULONG_MAX;
/*
* Processes which fork a lot of child processes are likely
* a good choice. We add half the vmsize of the children if they
* have an own mm. This prevents forking servers to flood the
* machine with an endless amount of children. In case a single
* child is eating the vast majority of memory, adding only half
* to the parents will make the child our kill candidate of choice.
*/
list_for_each_entry(child, &p->children, sibling) {
task_lock(child);
if (child->mm != mm && child->mm)
points += child->mm->total_vm/2 + 1;
task_unlock(child);
}
/*
* CPU time is in tens of seconds and run time is in thousands
* of seconds. There is no particular reason for this other than
* that it turned out to work very well in practice.
*/
cpu_time = (cputime_to_jiffies(p->utime) + cputime_to_jiffies(p->stime))
>> (SHIFT_HZ + 3);
if (uptime >= p->start_time.tv_sec)
run_time = (uptime - p->start_time.tv_sec) >> 10;
else
run_time = 0;
if (cpu_time)
points /= int_sqrt(cpu_time);
if (run_time)
points /= int_sqrt(int_sqrt(run_time));
/*
* Niced processes are most likely less important, so double
* their badness points.
*/
if (task_nice(p) > 0)
points *= 2;
/*
* Superuser processes are usually more important, so we make it
* less likely that we kill those.
*/
if (has_capability_noaudit(p, CAP_SYS_ADMIN) ||
has_capability_noaudit(p, CAP_SYS_RESOURCE))
points /= 4;
/*
* We don't want to kill a process with direct hardware access.
* Not only could that mess up the hardware, but usually users
* tend to only have this flag set on applications they think
* of as important.
*/
if (has_capability_noaudit(p, CAP_SYS_RAWIO))
points /= 4;
/*
* If p's nodes don't overlap ours, it may still help to kill p
* because p may have allocated or otherwise mapped memory on
* this node before. However it will be less likely.
*/
if (!cpuset_mems_allowed_intersects(current, p))
points /= 8;
/*
* Adjust the score by oom_adj.
*/
if (oom_adj) {
if (oom_adj > 0) {
if (!points)
points = 1;
points <<= oom_adj;
} else
points >>= -(oom_adj);
}
#ifdef DEBUG
printk(KERN_DEBUG "OOMkill: task %d (%s) got %lu points\n",
p->pid, p->comm, points);
#endif
return points;
}
/*
* Determine the type of allocation constraint.
*/
static inline enum oom_constraint constrained_alloc(struct zonelist *zonelist,
gfp_t gfp_mask)
{
#ifdef CONFIG_NUMA
struct zone *zone;
struct zoneref *z;
enum zone_type high_zoneidx = gfp_zone(gfp_mask);
nodemask_t nodes = node_states[N_HIGH_MEMORY];
for_each_zone_zonelist(zone, z, zonelist, high_zoneidx)
if (cpuset_zone_allowed_softwall(zone, gfp_mask))
node_clear(zone_to_nid(zone), nodes);
else
return CONSTRAINT_CPUSET;
if (!nodes_empty(nodes))
return CONSTRAINT_MEMORY_POLICY;
#endif
return CONSTRAINT_NONE;
}
/*
* Simple selection loop. We chose the process with the highest
* number of 'points'. We expect the caller will lock the tasklist.
*
* (not docbooked, we don't want this one cluttering up the manual)
*/
static struct task_struct *select_bad_process(unsigned long *ppoints,
struct mem_cgroup *mem)
{
struct task_struct *g, *p;
struct task_struct *chosen = NULL;
struct timespec uptime;
*ppoints = 0;
do_posix_clock_monotonic_gettime(&uptime);
do_each_thread(g, p) {
unsigned long points;
/*
* skip kernel threads and tasks which have already released
* their mm.
*/
if (!p->mm)
continue;
/* skip the init task */
if (is_global_init(p))
continue;
if (mem && !task_in_mem_cgroup(p, mem))
continue;
/*
* This task already has access to memory reserves and is
* being killed. Don't allow any other task access to the
* memory reserve.
*
* Note: this may have a chance of deadlock if it gets
* blocked waiting for another task which itself is waiting
* for memory. Is there a better alternative?
*/
if (test_tsk_thread_flag(p, TIF_MEMDIE))
return ERR_PTR(-1UL);
/*
* This is in the process of releasing memory so wait for it
* to finish before killing some other task by mistake.
*
* However, if p is the current task, we allow the 'kill' to
* go ahead if it is exiting: this will simply set TIF_MEMDIE,
* which will allow it to gain access to memory reserves in
* the process of exiting and releasing its resources.
* Otherwise we could get an easy OOM deadlock.
*/
if (p->flags & PF_EXITING) {
if (p != current)
return ERR_PTR(-1UL);
chosen = p;
*ppoints = ULONG_MAX;
}
points = badness(p, uptime.tv_sec);
if (points > *ppoints) {
chosen = p;
*ppoints = points;
}
} while_each_thread(g, p);
return chosen;
}
/**
* dump_tasks - dump current memory state of all system tasks
* @mem: target memory controller
*
* Dumps the current memory state of all system tasks, excluding kernel threads.
* State information includes task's pid, uid, tgid, vm size, rss, cpu, oom_adj
* score, and name.
*
* If the actual is non-NULL, only tasks that are a member of the mem_cgroup are
* shown.
*
* Call with tasklist_lock read-locked.
*/
static void dump_tasks(const struct mem_cgroup *mem)
{
struct task_struct *g, *p;
printk(KERN_INFO "[ pid ] uid tgid total_vm rss cpu oom_adj "
"name\n");
do_each_thread(g, p) {
struct mm_struct *mm;
if (mem && !task_in_mem_cgroup(p, mem))
continue;
if (!thread_group_leader(p))
continue;
task_lock(p);
mm = p->mm;
if (!mm) {
/*
* total_vm and rss sizes do not exist for tasks with no
* mm so there's no need to report them; they can't be
* oom killed anyway.
*/
task_unlock(p);
continue;
}
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);
task_unlock(p);
} while_each_thread(g, p);
}
/*
* Send SIGKILL to the selected process irrespective of CAP_SYS_RAW_IO
* flag though it's unlikely that we select a process with CAP_SYS_RAW_IO
* set.
*/
static void __oom_kill_task(struct task_struct *p, int verbose)
{
if (is_global_init(p)) {
WARN_ON(1);
printk(KERN_WARNING "tried to kill init!\n");
return;
}
if (!p->mm)
return;
if (verbose)
printk(KERN_ERR "Killed process %d (%s)\n",
task_pid_nr(p), p->comm);
/*
* We give our sacrificial lamb high priority and access to
* all the memory it needs. That way it should be able to
* exit() and clear out its resources quickly...
*/
p->rt.time_slice = HZ;
set_tsk_thread_flag(p, TIF_MEMDIE);
force_sig(SIGKILL, p);
}
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);
return 1;
}
task_unlock(p);
__oom_kill_task(p, 1);
/*
* kill all processes that share the ->mm (i.e. all threads),
* but are in a different thread group. Don't let them have access
* to memory reserves though, otherwise we might deplete all memory.
*/
do_each_thread(g, q) {
if (q->mm == mm && !same_thread_group(q, p))
force_sig(SIGKILL, q);
} while_each_thread(g, q);
return 0;
}
static int oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
unsigned long points, struct mem_cgroup *mem,
const char *message)
{
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);
cpuset_print_task_mems_allowed(current);
task_unlock(current);
dump_stack();
mem_cgroup_print_oom_info(mem, current);
show_mem();
if (sysctl_oom_dump_tasks)
dump_tasks(mem);
}
/*
* 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)) {
__oom_kill_task(p, 0);
return 0;
}
printk(KERN_ERR "%s: kill process %d (%s) score %li or a child\n",
message, task_pid_nr(p), p->comm, points);
/* Try to kill a child first */
list_for_each_entry(c, &p->children, sibling) {
if (c->mm == p->mm)
continue;
if (!oom_kill_task(c))
return 0;
}
return oom_kill_task(p);
}
#ifdef CONFIG_CGROUP_MEM_RES_CTLR
void mem_cgroup_out_of_memory(struct mem_cgroup *mem, gfp_t gfp_mask)
{
unsigned long points = 0;
struct task_struct *p;
read_lock(&tasklist_lock);
retry:
p = select_bad_process(&points, mem);
if (PTR_ERR(p) == -1UL)
goto out;
if (!p)
p = current;
if (oom_kill_process(p, gfp_mask, 0, points, mem,
"Memory cgroup out of memory"))
goto retry;
out:
read_unlock(&tasklist_lock);
}
#endif
static BLOCKING_NOTIFIER_HEAD(oom_notify_list);
int register_oom_notifier(struct notifier_block *nb)
{
return blocking_notifier_chain_register(&oom_notify_list, nb);
}
EXPORT_SYMBOL_GPL(register_oom_notifier);
int unregister_oom_notifier(struct notifier_block *nb)
{
return blocking_notifier_chain_unregister(&oom_notify_list, nb);
}
EXPORT_SYMBOL_GPL(unregister_oom_notifier);
/*
* Try to acquire the OOM killer lock for the zones in zonelist. Returns zero
* if a parallel OOM killing is already taking place that includes a zone in
* the zonelist. Otherwise, locks all zones in the zonelist and returns 1.
*/
int try_set_zone_oom(struct zonelist *zonelist, gfp_t gfp_mask)
{
struct zoneref *z;
struct zone *zone;
int ret = 1;
spin_lock(&zone_scan_lock);
for_each_zone_zonelist(zone, z, zonelist, gfp_zone(gfp_mask)) {
if (zone_is_oom_locked(zone)) {
ret = 0;
goto out;
}
}
for_each_zone_zonelist(zone, z, zonelist, gfp_zone(gfp_mask)) {
/*
* Lock each zone in the zonelist under zone_scan_lock so a
* parallel invocation of try_set_zone_oom() doesn't succeed
* when it shouldn't.
*/
zone_set_flag(zone, ZONE_OOM_LOCKED);
}
out:
spin_unlock(&zone_scan_lock);
return ret;
}
/*
* Clears the ZONE_OOM_LOCKED flag for all zones in the zonelist so that failed
* allocation attempts with zonelists containing them may now recall the OOM
* killer, if necessary.
*/
void clear_zonelist_oom(struct zonelist *zonelist, gfp_t gfp_mask)
{
struct zoneref *z;
struct zone *zone;
spin_lock(&zone_scan_lock);
for_each_zone_zonelist(zone, z, zonelist, gfp_zone(gfp_mask)) {
zone_clear_flag(zone, ZONE_OOM_LOCKED);
}
spin_unlock(&zone_scan_lock);
}
/*
* Must be called with tasklist_lock held for read.
*/
static void __out_of_memory(gfp_t gfp_mask, int order)
{
struct task_struct *p;
unsigned long points;
if (sysctl_oom_kill_allocating_task)
if (!oom_kill_process(current, gfp_mask, order, 0, NULL,
"Out of memory (oom_kill_allocating_task)"))
return;
retry:
/*
* Rambo mode: Shoot down a process and hope it solves whatever
* issues we may have.
*/
p = select_bad_process(&points, NULL);
if (PTR_ERR(p) == -1UL)
return;
/* Found nothing?!?! Either we hang forever, or we panic. */
if (!p) {
read_unlock(&tasklist_lock);
panic("Out of memory and no killable processes...\n");
}
if (oom_kill_process(p, gfp_mask, order, points, NULL,
"Out of memory"))
goto retry;
}
/*
* pagefault handler calls into here because it is out of memory but
* doesn't know exactly how or why.
*/
void pagefault_out_of_memory(void)
{
unsigned long freed = 0;
blocking_notifier_call_chain(&oom_notify_list, 0, &freed);
if (freed > 0)
/* Got some memory back in the last second. */
return;
/*
* If this is from memcg, oom-killer is already invoked.
* and not worth to go system-wide-oom.
*/
if (mem_cgroup_oom_called(current))
goto rest_and_return;
if (sysctl_panic_on_oom)
panic("out of memory from page fault. panic_on_oom is selected.\n");
read_lock(&tasklist_lock);
__out_of_memory(0, 0); /* unknown gfp_mask and order */
read_unlock(&tasklist_lock);
/*
* Give "p" a good chance of killing itself before we
* retry to allocate memory.
*/
rest_and_return:
if (!test_thread_flag(TIF_MEMDIE))
schedule_timeout_uninterruptible(1);
}
/**
* out_of_memory - kill the "best" process when we run out of memory
* @zonelist: zonelist pointer
* @gfp_mask: memory allocation flags
* @order: amount of memory being requested as a power of 2
*
* If we run out of memory, we have the choice between either
* killing a random task (bad), letting the system crash (worse)
* OR try to be smart about which process to kill. Note that we
* don't have to be perfect here, we just have to be good.
*/
void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask, int order)
{
unsigned long freed = 0;
enum oom_constraint constraint;
blocking_notifier_call_chain(&oom_notify_list, 0, &freed);
if (freed > 0)
/* Got some memory back in the last second. */
return;
if (sysctl_panic_on_oom == 2)
panic("out of memory. Compulsory panic_on_oom is selected.\n");
/*
* Check if there were limitations on the allocation (only relevant for
* NUMA) that may require different handling.
*/
constraint = constrained_alloc(zonelist, gfp_mask);
read_lock(&tasklist_lock);
switch (constraint) {
case CONSTRAINT_MEMORY_POLICY:
oom_kill_process(current, gfp_mask, order, 0, NULL,
"No available memory (MPOL_BIND)");
break;
case CONSTRAINT_NONE:
if (sysctl_panic_on_oom)
panic("out of memory. panic_on_oom is selected\n");
/* Fall-through */
case CONSTRAINT_CPUSET:
__out_of_memory(gfp_mask, order);
break;
}
read_unlock(&tasklist_lock);
/*
* Give "p" a good chance of killing itself before we
* retry to allocate memory unless "p" is current
*/
if (!test_thread_flag(TIF_MEMDIE))
schedule_timeout_uninterruptible(1);
}