* 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...
+ * Copyright (C) 2010 Google, Inc.
+ * Rewritten by David Rientjes
*
* The routines in this file are used to kill a process when
* we're seriously out of memory. This gets called from __alloc_pages()
#include <linux/oom.h>
#include <linux/mm.h>
#include <linux/err.h>
+#include <linux/gfp.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/export.h>
#include <linux/notifier.h>
#include <linux/memcontrol.h>
+#include <linux/mempolicy.h>
#include <linux/security.h>
+#include <linux/ptrace.h>
+#include <linux/freezer.h>
int sysctl_panic_on_oom;
int sysctl_oom_kill_allocating_task;
-int sysctl_oom_dump_tasks;
+int sysctl_oom_dump_tasks = 1;
static DEFINE_SPINLOCK(zone_scan_lock);
-/* #define DEBUG */
+
+/*
+ * compare_swap_oom_score_adj() - compare and swap current's oom_score_adj
+ * @old_val: old oom_score_adj for compare
+ * @new_val: new oom_score_adj for swap
+ *
+ * Sets the oom_score_adj value for current to @new_val iff its present value is
+ * @old_val. Usually used to reinstate a previous value to prevent racing with
+ * userspacing tuning the value in the interim.
+ */
+void compare_swap_oom_score_adj(int old_val, int new_val)
+{
+ struct sighand_struct *sighand = current->sighand;
+
+ spin_lock_irq(&sighand->siglock);
+ if (current->signal->oom_score_adj == old_val)
+ current->signal->oom_score_adj = new_val;
+ spin_unlock_irq(&sighand->siglock);
+}
/**
- * 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
+ * test_set_oom_score_adj() - set current's oom_score_adj and return old value
+ * @new_val: new oom_score_adj value
*
- * 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.
+ * Sets the oom_score_adj value for current to @new_val with proper
+ * synchronization and returns the old value. Usually used to temporarily
+ * set a value, save the old value in the caller, and then reinstate it later.
+ */
+int test_set_oom_score_adj(int new_val)
+{
+ struct sighand_struct *sighand = current->sighand;
+ int old_val;
+
+ spin_lock_irq(&sighand->siglock);
+ old_val = current->signal->oom_score_adj;
+ current->signal->oom_score_adj = new_val;
+ spin_unlock_irq(&sighand->siglock);
+
+ return old_val;
+}
+
+#ifdef CONFIG_NUMA
+/**
+ * has_intersects_mems_allowed() - check task eligiblity for kill
+ * @tsk: task struct of which task to consider
+ * @mask: nodemask passed to page allocator for mempolicy ooms
*
- * 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)
+ * Task eligibility is determined by whether or not a candidate task, @tsk,
+ * shares the same mempolicy nodes as current if it is bound by such a policy
+ * and whether or not it has the same set of allowed cpuset nodes.
*/
+static bool has_intersects_mems_allowed(struct task_struct *tsk,
+ const nodemask_t *mask)
+{
+ struct task_struct *start = tsk;
+
+ do {
+ if (mask) {
+ /*
+ * If this is a mempolicy constrained oom, tsk's
+ * cpuset is irrelevant. Only return true if its
+ * mempolicy intersects current, otherwise it may be
+ * needlessly killed.
+ */
+ if (mempolicy_nodemask_intersects(tsk, mask))
+ return true;
+ } else {
+ /*
+ * This is not a mempolicy constrained oom, so only
+ * check the mems of tsk's cpuset.
+ */
+ if (cpuset_mems_allowed_intersects(current, tsk))
+ return true;
+ }
+ } while_each_thread(start, tsk);
-unsigned long badness(struct task_struct *p, unsigned long uptime)
+ return false;
+}
+#else
+static bool has_intersects_mems_allowed(struct task_struct *tsk,
+ const nodemask_t *mask)
{
- unsigned long points, cpu_time, run_time;
- struct mm_struct *mm;
- struct task_struct *child;
+ return true;
+}
+#endif /* CONFIG_NUMA */
- task_lock(p);
- mm = p->mm;
- if (!mm) {
- task_unlock(p);
- return 0;
- }
+/*
+ * The process p may have detached its own ->mm while exiting or through
+ * use_mm(), but one or more of its subthreads may still have a valid
+ * pointer. Return p, or any of its subthreads with a valid ->mm, with
+ * task_lock() held.
+ */
+struct task_struct *find_lock_task_mm(struct task_struct *p)
+{
+ struct task_struct *t = p;
- /*
- * The memory size of the process is the basis for the badness.
- */
- points = mm->total_vm;
+ do {
+ task_lock(t);
+ if (likely(t->mm))
+ return t;
+ task_unlock(t);
+ } while_each_thread(p, t);
- /*
- * After this unlock we can no longer dereference local variable `mm'
- */
- task_unlock(p);
+ return NULL;
+}
- /*
- * swapoff can easily use up all memory, so kill those first.
- */
- if (p->flags & PF_SWAPOFF)
- return ULONG_MAX;
+/* return true if the task is not adequate as candidate victim task. */
+static bool oom_unkillable_task(struct task_struct *p,
+ const struct mem_cgroup *mem, const nodemask_t *nodemask)
+{
+ if (is_global_init(p))
+ return true;
+ if (p->flags & PF_KTHREAD)
+ return true;
- /*
- * 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);
- }
+ /* When mem_cgroup_out_of_memory() and p is not member of the group */
+ if (mem && !task_in_mem_cgroup(p, mem))
+ return true;
- /*
- * 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);
+ /* p may not have freeable memory in nodemask */
+ if (!has_intersects_mems_allowed(p, nodemask))
+ return true;
+
+ return false;
+}
+
+/**
+ * oom_badness - heuristic function to determine which candidate task to kill
+ * @p: task struct of which task we should calculate
+ * @totalpages: total present RAM allowed for page allocation
+ *
+ * The heuristic for determining which task to kill is made to be as simple and
+ * predictable as possible. The goal is to return the highest value for the
+ * task consuming the most memory to avoid subsequent oom failures.
+ */
+unsigned int oom_badness(struct task_struct *p, struct mem_cgroup *mem,
+ const nodemask_t *nodemask, unsigned long totalpages)
+{
+ long points;
- if (uptime >= p->start_time.tv_sec)
- run_time = (uptime - p->start_time.tv_sec) >> 10;
- else
- run_time = 0;
+ if (oom_unkillable_task(p, mem, nodemask))
+ return 0;
- if (cpu_time)
- points /= int_sqrt(cpu_time);
- if (run_time)
- points /= int_sqrt(int_sqrt(run_time));
+ p = find_lock_task_mm(p);
+ if (!p)
+ return 0;
+
+ if (p->signal->oom_score_adj == OOM_SCORE_ADJ_MIN) {
+ task_unlock(p);
+ return 0;
+ }
/*
- * Niced processes are most likely less important, so double
- * their badness points.
+ * The memory controller may have a limit of 0 bytes, so avoid a divide
+ * by zero, if necessary.
*/
- if (task_nice(p) > 0)
- points *= 2;
+ if (!totalpages)
+ totalpages = 1;
/*
- * Superuser processes are usually more important, so we make it
- * less likely that we kill those.
+ * The baseline for the badness score is the proportion of RAM that each
+ * task's rss, pagetable and swap space use.
*/
- if (has_capability_noaudit(p, CAP_SYS_ADMIN) ||
- has_capability_noaudit(p, CAP_SYS_RESOURCE))
- points /= 4;
+ points = get_mm_rss(p->mm) + p->mm->nr_ptes;
+ points += get_mm_counter(p->mm, MM_SWAPENTS);
+
+ points *= 1000;
+ points /= totalpages;
+ task_unlock(p);
/*
- * 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.
+ * Root processes get 3% bonus, just like the __vm_enough_memory()
+ * implementation used by LSMs.
*/
- if (has_capability_noaudit(p, CAP_SYS_RAWIO))
- points /= 4;
+ if (has_capability_noaudit(p, CAP_SYS_ADMIN))
+ points -= 30;
/*
- * 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.
+ * /proc/pid/oom_score_adj ranges from -1000 to +1000 such that it may
+ * either completely disable oom killing or always prefer a certain
+ * task.
*/
- if (!cpuset_mems_allowed_intersects(current, p))
- points /= 8;
+ points += p->signal->oom_score_adj;
/*
- * Adjust the score by oomkilladj.
+ * Never return 0 for an eligible task that may be killed since it's
+ * possible that no single user task uses more than 0.1% of memory and
+ * no single admin tasks uses more than 3.0%.
*/
- if (p->oomkilladj) {
- if (p->oomkilladj > 0) {
- if (!points)
- points = 1;
- points <<= p->oomkilladj;
- } else
- points >>= -(p->oomkilladj);
- }
-
-#ifdef DEBUG
- printk(KERN_DEBUG "OOMkill: task %d (%s) got %lu points\n",
- p->pid, p->comm, points);
-#endif
- return points;
+ if (points <= 0)
+ return 1;
+ return (points < 1000) ? points : 1000;
}
/*
* Determine the type of allocation constraint.
*/
-static inline enum oom_constraint constrained_alloc(struct zonelist *zonelist,
- gfp_t gfp_mask)
-{
#ifdef CONFIG_NUMA
+static enum oom_constraint constrained_alloc(struct zonelist *zonelist,
+ gfp_t gfp_mask, nodemask_t *nodemask,
+ unsigned long *totalpages)
+{
struct zone *zone;
struct zoneref *z;
enum zone_type high_zoneidx = gfp_zone(gfp_mask);
- nodemask_t nodes = node_states[N_HIGH_MEMORY];
+ bool cpuset_limited = false;
+ int nid;
- 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;
+ /* Default to all available memory */
+ *totalpages = totalram_pages + total_swap_pages;
- if (!nodes_empty(nodes))
+ if (!zonelist)
+ return CONSTRAINT_NONE;
+ /*
+ * Reach here only when __GFP_NOFAIL is used. So, we should avoid
+ * to kill current.We have to random task kill in this case.
+ * Hopefully, CONSTRAINT_THISNODE...but no way to handle it, now.
+ */
+ if (gfp_mask & __GFP_THISNODE)
+ return CONSTRAINT_NONE;
+
+ /*
+ * This is not a __GFP_THISNODE allocation, so a truncated nodemask in
+ * the page allocator means a mempolicy is in effect. Cpuset policy
+ * is enforced in get_page_from_freelist().
+ */
+ if (nodemask && !nodes_subset(node_states[N_HIGH_MEMORY], *nodemask)) {
+ *totalpages = total_swap_pages;
+ for_each_node_mask(nid, *nodemask)
+ *totalpages += node_spanned_pages(nid);
return CONSTRAINT_MEMORY_POLICY;
-#endif
+ }
+ /* Check this allocation failure is caused by cpuset's wall function */
+ for_each_zone_zonelist_nodemask(zone, z, zonelist,
+ high_zoneidx, nodemask)
+ if (!cpuset_zone_allowed_softwall(zone, gfp_mask))
+ cpuset_limited = true;
+
+ if (cpuset_limited) {
+ *totalpages = total_swap_pages;
+ for_each_node_mask(nid, cpuset_current_mems_allowed)
+ *totalpages += node_spanned_pages(nid);
+ return CONSTRAINT_CPUSET;
+ }
return CONSTRAINT_NONE;
}
+#else
+static enum oom_constraint constrained_alloc(struct zonelist *zonelist,
+ gfp_t gfp_mask, nodemask_t *nodemask,
+ unsigned long *totalpages)
+{
+ *totalpages = totalram_pages + total_swap_pages;
+ return CONSTRAINT_NONE;
+}
+#endif
/*
* Simple selection loop. We chose the process with the highest
*
* (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)
+static struct task_struct *select_bad_process(unsigned int *ppoints,
+ unsigned long totalpages, struct mem_cgroup *mem,
+ const nodemask_t *nodemask)
{
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;
+ unsigned int 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))
+ if (p->exit_state)
continue;
- if (mem && !task_in_mem_cgroup(p, mem))
+ if (oom_unkillable_task(p, mem, nodemask))
continue;
/*
* blocked waiting for another task which itself is waiting
* for memory. Is there a better alternative?
*/
- if (test_tsk_thread_flag(p, TIF_MEMDIE))
+ if (test_tsk_thread_flag(p, TIF_MEMDIE)) {
+ if (unlikely(frozen(p)))
+ thaw_process(p);
return ERR_PTR(-1UL);
+ }
+ if (!p->mm)
+ continue;
- /*
- * 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;
+ /*
+ * If p is the current task and is in the process of
+ * releasing memory, we allow the "kill" to set
+ * TIF_MEMDIE, which will allow it to gain access to
+ * memory reserves. Otherwise, it may stall forever.
+ *
+ * The loop isn't broken here, however, in case other
+ * threads are found to have already been oom killed.
+ */
+ if (p == current) {
+ chosen = p;
+ *ppoints = 1000;
+ } else {
+ /*
+ * If this task is not being ptraced on exit,
+ * then wait for it to finish before killing
+ * some other task unnecessarily.
+ */
+ if (!(p->group_leader->ptrace & PT_TRACE_EXIT))
+ return ERR_PTR(-1UL);
+ }
}
- if (p->oomkilladj == OOM_DISABLE)
- continue;
-
- points = badness(p, uptime.tv_sec);
- if (points > *ppoints || !chosen) {
+ points = oom_badness(p, mem, nodemask, totalpages);
+ if (points > *ppoints) {
chosen = p;
*ppoints = points;
}
/**
* dump_tasks - dump current memory state of all system tasks
- * @mem: target memory controller
+ * @mem: current's memory controller, if constrained
+ * @nodemask: nodemask passed to page allocator for mempolicy ooms
*
- * Dumps the current memory state of all system tasks, excluding kernel threads.
+ * Dumps the current memory state of all eligible tasks. Tasks not in the same
+ * memcg, not in the same cpuset, or bound to a disjoint set of mempolicy nodes
+ * are not shown.
* 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.
+ * value, oom_score_adj value, and name.
*
* Call with tasklist_lock read-locked.
*/
-static void dump_tasks(const struct mem_cgroup *mem)
+static void dump_tasks(const struct mem_cgroup *mem, const nodemask_t *nodemask)
{
- struct task_struct *g, *p;
+ struct task_struct *p;
+ struct task_struct *task;
- printk(KERN_INFO "[ pid ] uid tgid total_vm rss cpu oom_adj "
- "name\n");
- do_each_thread(g, p) {
- /*
- * total_vm and rss sizes do not exist for tasks with a
- * detached mm so there's no need to report them.
- */
- if (!p->mm)
+ pr_info("[ pid ] uid tgid total_vm rss cpu oom_adj oom_score_adj name\n");
+ for_each_process(p) {
+ if (oom_unkillable_task(p, mem, nodemask))
continue;
- if (mem && !task_in_mem_cgroup(p, mem))
- continue;
- if (!thread_group_leader(p))
+
+ task = find_lock_task_mm(p);
+ if (!task) {
+ /*
+ * This is a kthread or all of p's threads have already
+ * detached their mm's. There's no need to report
+ * them; they can't be oom killed anyway.
+ */
continue;
+ }
- task_lock(p);
- printk(KERN_INFO "[%5d] %5d %5d %8lu %8lu %3d %3d %s\n",
- p->pid, __task_cred(p)->uid, p->tgid,
- p->mm->total_vm, get_mm_rss(p->mm), (int)task_cpu(p),
- p->oomkilladj, p->comm);
- task_unlock(p);
- } while_each_thread(g, p);
+ pr_info("[%5d] %5d %5d %8lu %8lu %3u %3d %5d %s\n",
+ task->pid, task_uid(task), task->tgid,
+ task->mm->total_vm, get_mm_rss(task->mm),
+ task_cpu(task), task->signal->oom_adj,
+ task->signal->oom_score_adj, task->comm);
+ task_unlock(task);
+ }
}
-/*
- * 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)
+static void dump_header(struct task_struct *p, gfp_t gfp_mask, int order,
+ struct mem_cgroup *mem, const nodemask_t *nodemask)
{
- if (is_global_init(p)) {
- WARN_ON(1);
- printk(KERN_WARNING "tried to kill init!\n");
- return;
- }
-
- 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",
- 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);
+ task_lock(current);
+ pr_warning("%s invoked oom-killer: gfp_mask=0x%x, order=%d, "
+ "oom_adj=%d, oom_score_adj=%d\n",
+ current->comm, gfp_mask, order, current->signal->oom_adj,
+ current->signal->oom_score_adj);
+ cpuset_print_task_mems_allowed(current);
+ task_unlock(current);
+ dump_stack();
+ mem_cgroup_print_oom_info(mem, p);
+ show_mem(SHOW_MEM_FILTER_NODES);
+ if (sysctl_oom_dump_tasks)
+ dump_tasks(mem, nodemask);
}
-static int oom_kill_task(struct task_struct *p)
+#define K(x) ((x) << (PAGE_SHIFT-10))
+static int oom_kill_task(struct task_struct *p, struct mem_cgroup *mem)
{
+ struct task_struct *q;
struct mm_struct *mm;
- struct task_struct *g, *q;
-
- 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)
+ p = find_lock_task_mm(p);
+ if (!p)
return 1;
- /*
- * 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);
+ /* mm cannot be safely dereferenced after task_unlock(p) */
+ mm = p->mm;
- __oom_kill_task(p, 1);
+ pr_err("Killed process %d (%s) total-vm:%lukB, anon-rss:%lukB, file-rss:%lukB\n",
+ task_pid_nr(p), p->comm, K(p->mm->total_vm),
+ K(get_mm_counter(p->mm, MM_ANONPAGES)),
+ K(get_mm_counter(p->mm, MM_FILEPAGES)));
+ task_unlock(p);
/*
- * 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.
+ * Kill all user processes sharing p->mm in other thread groups, if any.
+ * They don't get access to memory reserves or a higher scheduler
+ * priority, though, to avoid depletion of all memory or task
+ * starvation. This prevents mm->mmap_sem livelock when an oom killed
+ * task cannot exit because it requires the semaphore and its contended
+ * by another thread trying to allocate memory itself. That thread will
+ * now get access to memory reserves since it has a pending fatal
+ * signal.
*/
- do_each_thread(g, q) {
- if (q->mm == mm && !same_thread_group(q, p))
+ for_each_process(q)
+ if (q->mm == mm && !same_thread_group(q, p) &&
+ !(q->flags & PF_KTHREAD)) {
+ if (q->signal->oom_score_adj == OOM_SCORE_ADJ_MIN)
+ continue;
+
+ task_lock(q); /* Protect ->comm from prctl() */
+ pr_err("Kill process %d (%s) sharing same memory\n",
+ task_pid_nr(q), q->comm);
+ task_unlock(q);
force_sig(SIGKILL, q);
- } while_each_thread(g, q);
+ }
+
+ set_tsk_thread_flag(p, TIF_MEMDIE);
+ force_sig(SIGKILL, p);
return 0;
}
+#undef K
static int oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
- unsigned long points, struct mem_cgroup *mem,
+ unsigned int points, unsigned long totalpages,
+ struct mem_cgroup *mem, nodemask_t *nodemask,
const char *message)
{
- struct task_struct *c;
-
- if (printk_ratelimit()) {
- printk(KERN_WARNING "%s invoked oom-killer: "
- "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();
- mem_cgroup_print_oom_info(mem, current);
- show_mem();
- if (sysctl_oom_dump_tasks)
- dump_tasks(mem);
- }
+ struct task_struct *victim = p;
+ struct task_struct *child;
+ struct task_struct *t = p;
+ unsigned int victim_points = 0;
+
+ if (printk_ratelimit())
+ dump_header(p, gfp_mask, order, mem, nodemask);
/*
* 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 (p->flags & PF_EXITING) {
- __oom_kill_task(p, 0);
+ set_tsk_thread_flag(p, TIF_MEMDIE);
return 0;
}
- printk(KERN_ERR "%s: kill process %d (%s) score %li or a child\n",
- message, task_pid_nr(p), p->comm, points);
+ task_lock(p);
+ pr_err("%s: Kill process %d (%s) score %d or sacrifice child\n",
+ message, task_pid_nr(p), p->comm, points);
+ task_unlock(p);
- /* 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;
+ /*
+ * If any of p's children has a different mm and is eligible for kill,
+ * the one with the highest oom_badness() score is sacrificed for its
+ * parent. This attempts to lose the minimal amount of work done while
+ * still freeing memory.
+ */
+ do {
+ list_for_each_entry(child, &t->children, sibling) {
+ unsigned int child_points;
+
+ if (child->mm == p->mm)
+ continue;
+ /*
+ * oom_badness() returns 0 if the thread is unkillable
+ */
+ child_points = oom_badness(child, mem, nodemask,
+ totalpages);
+ if (child_points > victim_points) {
+ victim = child;
+ victim_points = child_points;
+ }
+ }
+ } while_each_thread(p, t);
+
+ return oom_kill_task(victim, mem);
+}
+
+/*
+ * Determines whether the kernel must panic because of the panic_on_oom sysctl.
+ */
+static void check_panic_on_oom(enum oom_constraint constraint, gfp_t gfp_mask,
+ int order, const nodemask_t *nodemask)
+{
+ if (likely(!sysctl_panic_on_oom))
+ return;
+ if (sysctl_panic_on_oom != 2) {
+ /*
+ * panic_on_oom == 1 only affects CONSTRAINT_NONE, the kernel
+ * does not panic for cpuset, mempolicy, or memcg allocation
+ * failures.
+ */
+ if (constraint != CONSTRAINT_NONE)
+ return;
}
- return oom_kill_task(p);
+ read_lock(&tasklist_lock);
+ dump_header(NULL, gfp_mask, order, NULL, nodemask);
+ read_unlock(&tasklist_lock);
+ panic("Out of memory: %s panic_on_oom is enabled\n",
+ sysctl_panic_on_oom == 2 ? "compulsory" : "system-wide");
}
#ifdef CONFIG_CGROUP_MEM_RES_CTLR
void mem_cgroup_out_of_memory(struct mem_cgroup *mem, gfp_t gfp_mask)
{
- unsigned long points = 0;
+ unsigned long limit;
+ unsigned int points = 0;
struct task_struct *p;
+ /*
+ * If current has a pending SIGKILL, then automatically select it. The
+ * goal is to allow it to allocate so that it may quickly exit and free
+ * its memory.
+ */
+ if (fatal_signal_pending(current)) {
+ set_thread_flag(TIF_MEMDIE);
+ return;
+ }
+
+ check_panic_on_oom(CONSTRAINT_MEMCG, gfp_mask, 0, NULL);
+ limit = mem_cgroup_get_limit(mem) >> PAGE_SHIFT;
read_lock(&tasklist_lock);
retry:
- p = select_bad_process(&points, mem);
- if (PTR_ERR(p) == -1UL)
+ p = select_bad_process(&points, limit, mem, NULL);
+ if (!p || PTR_ERR(p) == -1UL)
goto out;
- if (!p)
- p = current;
-
- if (oom_kill_process(p, gfp_mask, 0, points, mem,
+ if (oom_kill_process(p, gfp_mask, 0, points, limit, mem, NULL,
"Memory cgroup out of memory"))
goto retry;
out:
* 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)
+int try_set_zonelist_oom(struct zonelist *zonelist, gfp_t gfp_mask)
{
struct zoneref *z;
struct zone *zone;
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
+ * parallel invocation of try_set_zonelist_oom() doesn't succeed
* when it shouldn't.
*/
zone_set_flag(zone, ZONE_OOM_LOCKED);
}
/*
- * Must be called with tasklist_lock held for read.
+ * Try to acquire the oom killer lock for all system zones. Returns zero if a
+ * parallel oom killing is taking place, otherwise locks all zones and returns
+ * non-zero.
*/
-static void __out_of_memory(gfp_t gfp_mask, int order)
+static int try_set_system_oom(void)
{
- if (sysctl_oom_kill_allocating_task) {
- oom_kill_process(current, gfp_mask, order, 0, NULL,
- "Out of memory (oom_kill_allocating_task)");
-
- } else {
- unsigned long points;
- struct task_struct *p;
-
-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;
+ struct zone *zone;
+ int ret = 1;
- /* Found nothing?!?! Either we hang forever, or we panic. */
- if (!p) {
- read_unlock(&tasklist_lock);
- panic("Out of memory and no killable processes...\n");
+ spin_lock(&zone_scan_lock);
+ for_each_populated_zone(zone)
+ if (zone_is_oom_locked(zone)) {
+ ret = 0;
+ goto out;
}
-
- if (oom_kill_process(p, gfp_mask, order, points, NULL,
- "Out of memory"))
- goto retry;
- }
+ for_each_populated_zone(zone)
+ zone_set_flag(zone, ZONE_OOM_LOCKED);
+out:
+ spin_unlock(&zone_scan_lock);
+ return ret;
}
/*
- * pagefault handler calls into here because it is out of memory but
- * doesn't know exactly how or why.
+ * Clears ZONE_OOM_LOCKED for all system zones so that failed allocation
+ * attempts or page faults may now recall the oom killer, if necessary.
*/
-void pagefault_out_of_memory(void)
+static void clear_system_oom(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);
+ struct zone *zone;
- /*
- * 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);
+ spin_lock(&zone_scan_lock);
+ for_each_populated_zone(zone)
+ zone_clear_flag(zone, ZONE_OOM_LOCKED);
+ spin_unlock(&zone_scan_lock);
}
/**
* @zonelist: zonelist pointer
* @gfp_mask: memory allocation flags
* @order: amount of memory being requested as a power of 2
+ * @nodemask: nodemask passed to page allocator
*
* 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)
+void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask,
+ int order, nodemask_t *nodemask)
{
+ const nodemask_t *mpol_mask;
+ struct task_struct *p;
+ unsigned long totalpages;
unsigned long freed = 0;
- enum oom_constraint constraint;
+ unsigned int points;
+ enum oom_constraint constraint = CONSTRAINT_NONE;
+ int killed = 0;
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");
+ /*
+ * If current has a pending SIGKILL, then automatically select it. The
+ * goal is to allow it to allocate so that it may quickly exit and free
+ * its memory.
+ */
+ if (fatal_signal_pending(current)) {
+ set_thread_flag(TIF_MEMDIE);
+ return;
+ }
/*
* Check if there were limitations on the allocation (only relevant for
* NUMA) that may require different handling.
*/
- constraint = constrained_alloc(zonelist, gfp_mask);
+ constraint = constrained_alloc(zonelist, gfp_mask, nodemask,
+ &totalpages);
+ mpol_mask = (constraint == CONSTRAINT_MEMORY_POLICY) ? nodemask : NULL;
+ check_panic_on_oom(constraint, gfp_mask, order, mpol_mask);
+
read_lock(&tasklist_lock);
+ if (sysctl_oom_kill_allocating_task &&
+ !oom_unkillable_task(current, NULL, nodemask) &&
+ current->mm) {
+ /*
+ * oom_kill_process() needs tasklist_lock held. If it returns
+ * non-zero, current could not be killed so we must fallback to
+ * the tasklist scan.
+ */
+ if (!oom_kill_process(current, gfp_mask, order, 0, totalpages,
+ NULL, nodemask,
+ "Out of memory (oom_kill_allocating_task)"))
+ goto out;
+ }
- 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;
+retry:
+ p = select_bad_process(&points, totalpages, NULL, mpol_mask);
+ if (PTR_ERR(p) == -1UL)
+ goto out;
+
+ /* Found nothing?!?! Either we hang forever, or we panic. */
+ if (!p) {
+ dump_header(NULL, gfp_mask, order, NULL, mpol_mask);
+ read_unlock(&tasklist_lock);
+ panic("Out of memory and no killable processes...\n");
}
+ if (oom_kill_process(p, gfp_mask, order, points, totalpages, NULL,
+ nodemask, "Out of memory"))
+ goto retry;
+ killed = 1;
+out:
read_unlock(&tasklist_lock);
/*
* Give "p" a good chance of killing itself before we
* retry to allocate memory unless "p" is current
*/
+ if (killed && !test_thread_flag(TIF_MEMDIE))
+ schedule_timeout_uninterruptible(1);
+}
+
+/*
+ * The pagefault handler calls here because it is out of memory, so kill a
+ * memory-hogging task. If a populated zone has ZONE_OOM_LOCKED set, a parallel
+ * oom killing is already in progress so do nothing. If a task is found with
+ * TIF_MEMDIE set, it has been killed so do nothing and allow it to exit.
+ */
+void pagefault_out_of_memory(void)
+{
+ if (try_set_system_oom()) {
+ out_of_memory(NULL, 0, 0, NULL);
+ clear_system_oom();
+ }
if (!test_thread_flag(TIF_MEMDIE))
schedule_timeout_uninterruptible(1);
}
projects / linux-flexiantxendom0.git / blobdiff