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dc6c9a35b6
Dave noticed that unprivileged process can allocate significant amount of memory -- >500 MiB on x86_64 -- and stay unnoticed by oom-killer and memory cgroup. The trick is to allocate a lot of PMD page tables. Linux kernel doesn't account PMD tables to the process, only PTE. The use-cases below use few tricks to allocate a lot of PMD page tables while keeping VmRSS and VmPTE low. oom_score for the process will be 0. #include <errno.h> #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <sys/mman.h> #include <sys/prctl.h> #define PUD_SIZE (1UL << 30) #define PMD_SIZE (1UL << 21) #define NR_PUD 130000 int main(void) { char *addr = NULL; unsigned long i; prctl(PR_SET_THP_DISABLE); for (i = 0; i < NR_PUD ; i++) { addr = mmap(addr + PUD_SIZE, PUD_SIZE, PROT_WRITE|PROT_READ, MAP_ANONYMOUS|MAP_PRIVATE, -1, 0); if (addr == MAP_FAILED) { perror("mmap"); break; } *addr = 'x'; munmap(addr, PMD_SIZE); mmap(addr, PMD_SIZE, PROT_WRITE|PROT_READ, MAP_ANONYMOUS|MAP_PRIVATE|MAP_FIXED, -1, 0); if (addr == MAP_FAILED) perror("re-mmap"), exit(1); } printf("PID %d consumed %lu KiB in PMD page tables\n", getpid(), i * 4096 >> 10); return pause(); } The patch addresses the issue by account PMD tables to the process the same way we account PTE. The main place where PMD tables is accounted is __pmd_alloc() and free_pmd_range(). But there're few corner cases: - HugeTLB can share PMD page tables. The patch handles by accounting the table to all processes who share it. - x86 PAE pre-allocates few PMD tables on fork. - Architectures with FIRST_USER_ADDRESS > 0. We need to adjust sanity check on exit(2). Accounting only happens on configuration where PMD page table's level is present (PMD is not folded). As with nr_ptes we use per-mm counter. The counter value is used to calculate baseline for badness score by oom-killer. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reported-by: Dave Hansen <dave.hansen@linux.intel.com> Cc: Hugh Dickins <hughd@google.com> Reviewed-by: Cyrill Gorcunov <gorcunov@openvz.org> Cc: Pavel Emelyanov <xemul@openvz.org> Cc: David Rientjes <rientjes@google.com> Tested-by: Sedat Dilek <sedat.dilek@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
832 lines
23 KiB
C
832 lines
23 KiB
C
/*
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* linux/mm/oom_kill.c
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*
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* Copyright (C) 1998,2000 Rik van Riel
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* Thanks go out to Claus Fischer for some serious inspiration and
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* for goading me into coding this file...
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* Copyright (C) 2010 Google, Inc.
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* Rewritten by David Rientjes
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*
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* The routines in this file are used to kill a process when
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* we're seriously out of memory. This gets called from __alloc_pages()
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* in mm/page_alloc.c when we really run out of memory.
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*
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* Since we won't call these routines often (on a well-configured
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* machine) this file will double as a 'coding guide' and a signpost
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* for newbie kernel hackers. It features several pointers to major
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* kernel subsystems and hints as to where to find out what things do.
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*/
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#include <linux/oom.h>
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#include <linux/mm.h>
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#include <linux/err.h>
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#include <linux/gfp.h>
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#include <linux/sched.h>
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#include <linux/swap.h>
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#include <linux/timex.h>
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#include <linux/jiffies.h>
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#include <linux/cpuset.h>
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#include <linux/export.h>
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#include <linux/notifier.h>
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#include <linux/memcontrol.h>
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#include <linux/mempolicy.h>
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#include <linux/security.h>
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#include <linux/ptrace.h>
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#include <linux/freezer.h>
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#include <linux/ftrace.h>
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#include <linux/ratelimit.h>
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#define CREATE_TRACE_POINTS
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#include <trace/events/oom.h>
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int sysctl_panic_on_oom;
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int sysctl_oom_kill_allocating_task;
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int sysctl_oom_dump_tasks = 1;
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static DEFINE_SPINLOCK(zone_scan_lock);
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#ifdef CONFIG_NUMA
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/**
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* has_intersects_mems_allowed() - check task eligiblity for kill
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* @start: task struct of which task to consider
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* @mask: nodemask passed to page allocator for mempolicy ooms
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*
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* Task eligibility is determined by whether or not a candidate task, @tsk,
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* shares the same mempolicy nodes as current if it is bound by such a policy
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* and whether or not it has the same set of allowed cpuset nodes.
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*/
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static bool has_intersects_mems_allowed(struct task_struct *start,
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const nodemask_t *mask)
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{
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struct task_struct *tsk;
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bool ret = false;
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rcu_read_lock();
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for_each_thread(start, tsk) {
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if (mask) {
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/*
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* If this is a mempolicy constrained oom, tsk's
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* cpuset is irrelevant. Only return true if its
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* mempolicy intersects current, otherwise it may be
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* needlessly killed.
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*/
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ret = mempolicy_nodemask_intersects(tsk, mask);
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} else {
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/*
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* This is not a mempolicy constrained oom, so only
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* check the mems of tsk's cpuset.
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*/
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ret = cpuset_mems_allowed_intersects(current, tsk);
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}
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if (ret)
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break;
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}
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rcu_read_unlock();
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return ret;
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}
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#else
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static bool has_intersects_mems_allowed(struct task_struct *tsk,
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const nodemask_t *mask)
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{
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return true;
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}
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#endif /* CONFIG_NUMA */
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/*
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* The process p may have detached its own ->mm while exiting or through
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* use_mm(), but one or more of its subthreads may still have a valid
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* pointer. Return p, or any of its subthreads with a valid ->mm, with
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* task_lock() held.
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*/
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struct task_struct *find_lock_task_mm(struct task_struct *p)
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{
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struct task_struct *t;
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rcu_read_lock();
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for_each_thread(p, t) {
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task_lock(t);
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if (likely(t->mm))
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goto found;
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task_unlock(t);
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}
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t = NULL;
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found:
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rcu_read_unlock();
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return t;
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}
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/* return true if the task is not adequate as candidate victim task. */
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static bool oom_unkillable_task(struct task_struct *p,
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struct mem_cgroup *memcg, const nodemask_t *nodemask)
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{
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if (is_global_init(p))
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return true;
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if (p->flags & PF_KTHREAD)
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return true;
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/* When mem_cgroup_out_of_memory() and p is not member of the group */
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if (memcg && !task_in_mem_cgroup(p, memcg))
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return true;
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/* p may not have freeable memory in nodemask */
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if (!has_intersects_mems_allowed(p, nodemask))
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return true;
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return false;
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}
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/**
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* oom_badness - heuristic function to determine which candidate task to kill
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* @p: task struct of which task we should calculate
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* @totalpages: total present RAM allowed for page allocation
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*
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* The heuristic for determining which task to kill is made to be as simple and
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* predictable as possible. The goal is to return the highest value for the
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* task consuming the most memory to avoid subsequent oom failures.
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*/
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unsigned long oom_badness(struct task_struct *p, struct mem_cgroup *memcg,
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const nodemask_t *nodemask, unsigned long totalpages)
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{
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long points;
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long adj;
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if (oom_unkillable_task(p, memcg, nodemask))
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return 0;
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p = find_lock_task_mm(p);
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if (!p)
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return 0;
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adj = (long)p->signal->oom_score_adj;
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if (adj == OOM_SCORE_ADJ_MIN) {
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task_unlock(p);
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return 0;
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}
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/*
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* The baseline for the badness score is the proportion of RAM that each
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* task's rss, pagetable and swap space use.
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*/
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points = get_mm_rss(p->mm) + get_mm_counter(p->mm, MM_SWAPENTS) +
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atomic_long_read(&p->mm->nr_ptes) + mm_nr_pmds(p->mm);
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task_unlock(p);
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/*
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* Root processes get 3% bonus, just like the __vm_enough_memory()
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* implementation used by LSMs.
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*/
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if (has_capability_noaudit(p, CAP_SYS_ADMIN))
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points -= (points * 3) / 100;
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/* Normalize to oom_score_adj units */
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adj *= totalpages / 1000;
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points += adj;
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/*
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* Never return 0 for an eligible task regardless of the root bonus and
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* oom_score_adj (oom_score_adj can't be OOM_SCORE_ADJ_MIN here).
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*/
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return points > 0 ? points : 1;
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}
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/*
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* Determine the type of allocation constraint.
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*/
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#ifdef CONFIG_NUMA
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static enum oom_constraint constrained_alloc(struct zonelist *zonelist,
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gfp_t gfp_mask, nodemask_t *nodemask,
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unsigned long *totalpages)
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{
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struct zone *zone;
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struct zoneref *z;
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enum zone_type high_zoneidx = gfp_zone(gfp_mask);
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bool cpuset_limited = false;
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int nid;
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/* Default to all available memory */
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*totalpages = totalram_pages + total_swap_pages;
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if (!zonelist)
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return CONSTRAINT_NONE;
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/*
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* Reach here only when __GFP_NOFAIL is used. So, we should avoid
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* to kill current.We have to random task kill in this case.
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* Hopefully, CONSTRAINT_THISNODE...but no way to handle it, now.
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*/
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if (gfp_mask & __GFP_THISNODE)
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return CONSTRAINT_NONE;
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/*
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* This is not a __GFP_THISNODE allocation, so a truncated nodemask in
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* the page allocator means a mempolicy is in effect. Cpuset policy
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* is enforced in get_page_from_freelist().
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*/
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if (nodemask && !nodes_subset(node_states[N_MEMORY], *nodemask)) {
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*totalpages = total_swap_pages;
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for_each_node_mask(nid, *nodemask)
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*totalpages += node_spanned_pages(nid);
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return CONSTRAINT_MEMORY_POLICY;
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}
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/* Check this allocation failure is caused by cpuset's wall function */
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for_each_zone_zonelist_nodemask(zone, z, zonelist,
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high_zoneidx, nodemask)
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if (!cpuset_zone_allowed(zone, gfp_mask))
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cpuset_limited = true;
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if (cpuset_limited) {
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*totalpages = total_swap_pages;
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for_each_node_mask(nid, cpuset_current_mems_allowed)
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*totalpages += node_spanned_pages(nid);
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return CONSTRAINT_CPUSET;
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}
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return CONSTRAINT_NONE;
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}
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#else
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static enum oom_constraint constrained_alloc(struct zonelist *zonelist,
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gfp_t gfp_mask, nodemask_t *nodemask,
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unsigned long *totalpages)
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{
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*totalpages = totalram_pages + total_swap_pages;
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return CONSTRAINT_NONE;
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}
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#endif
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enum oom_scan_t oom_scan_process_thread(struct task_struct *task,
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unsigned long totalpages, const nodemask_t *nodemask,
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bool force_kill)
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{
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if (oom_unkillable_task(task, NULL, nodemask))
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return OOM_SCAN_CONTINUE;
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/*
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* This task already has access to memory reserves and is being killed.
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* Don't allow any other task to have access to the reserves.
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*/
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if (test_tsk_thread_flag(task, TIF_MEMDIE)) {
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if (!force_kill)
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return OOM_SCAN_ABORT;
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}
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if (!task->mm)
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return OOM_SCAN_CONTINUE;
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/*
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* If task is allocating a lot of memory and has been marked to be
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* killed first if it triggers an oom, then select it.
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*/
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if (oom_task_origin(task))
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return OOM_SCAN_SELECT;
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if (task_will_free_mem(task) && !force_kill)
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return OOM_SCAN_ABORT;
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return OOM_SCAN_OK;
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}
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/*
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* Simple selection loop. We chose the process with the highest
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* number of 'points'. Returns -1 on scan abort.
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*
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* (not docbooked, we don't want this one cluttering up the manual)
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*/
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static struct task_struct *select_bad_process(unsigned int *ppoints,
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unsigned long totalpages, const nodemask_t *nodemask,
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bool force_kill)
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{
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struct task_struct *g, *p;
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struct task_struct *chosen = NULL;
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unsigned long chosen_points = 0;
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rcu_read_lock();
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for_each_process_thread(g, p) {
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unsigned int points;
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switch (oom_scan_process_thread(p, totalpages, nodemask,
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force_kill)) {
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case OOM_SCAN_SELECT:
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chosen = p;
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chosen_points = ULONG_MAX;
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/* fall through */
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case OOM_SCAN_CONTINUE:
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continue;
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case OOM_SCAN_ABORT:
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rcu_read_unlock();
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return (struct task_struct *)(-1UL);
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case OOM_SCAN_OK:
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break;
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};
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points = oom_badness(p, NULL, nodemask, totalpages);
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if (!points || points < chosen_points)
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continue;
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/* Prefer thread group leaders for display purposes */
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if (points == chosen_points && thread_group_leader(chosen))
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continue;
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chosen = p;
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chosen_points = points;
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}
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if (chosen)
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get_task_struct(chosen);
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rcu_read_unlock();
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*ppoints = chosen_points * 1000 / totalpages;
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return chosen;
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}
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/**
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* dump_tasks - dump current memory state of all system tasks
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* @memcg: current's memory controller, if constrained
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* @nodemask: nodemask passed to page allocator for mempolicy ooms
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*
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* Dumps the current memory state of all eligible tasks. Tasks not in the same
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* memcg, not in the same cpuset, or bound to a disjoint set of mempolicy nodes
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* are not shown.
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* State information includes task's pid, uid, tgid, vm size, rss, nr_ptes,
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* swapents, oom_score_adj value, and name.
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*/
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static void dump_tasks(struct mem_cgroup *memcg, const nodemask_t *nodemask)
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{
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struct task_struct *p;
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struct task_struct *task;
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pr_info("[ pid ] uid tgid total_vm rss nr_ptes nr_pmds swapents oom_score_adj name\n");
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rcu_read_lock();
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for_each_process(p) {
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if (oom_unkillable_task(p, memcg, nodemask))
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continue;
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task = find_lock_task_mm(p);
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if (!task) {
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/*
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* This is a kthread or all of p's threads have already
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* detached their mm's. There's no need to report
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* them; they can't be oom killed anyway.
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*/
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continue;
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}
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pr_info("[%5d] %5d %5d %8lu %8lu %7ld %7ld %8lu %5hd %s\n",
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task->pid, from_kuid(&init_user_ns, task_uid(task)),
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task->tgid, task->mm->total_vm, get_mm_rss(task->mm),
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atomic_long_read(&task->mm->nr_ptes),
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mm_nr_pmds(task->mm),
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get_mm_counter(task->mm, MM_SWAPENTS),
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task->signal->oom_score_adj, task->comm);
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task_unlock(task);
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}
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rcu_read_unlock();
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}
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static void dump_header(struct task_struct *p, gfp_t gfp_mask, int order,
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struct mem_cgroup *memcg, const nodemask_t *nodemask)
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{
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task_lock(current);
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pr_warning("%s invoked oom-killer: gfp_mask=0x%x, order=%d, "
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"oom_score_adj=%hd\n",
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current->comm, gfp_mask, order,
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current->signal->oom_score_adj);
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cpuset_print_task_mems_allowed(current);
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task_unlock(current);
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dump_stack();
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if (memcg)
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mem_cgroup_print_oom_info(memcg, p);
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else
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show_mem(SHOW_MEM_FILTER_NODES);
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if (sysctl_oom_dump_tasks)
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dump_tasks(memcg, nodemask);
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}
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/*
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* Number of OOM victims in flight
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*/
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static atomic_t oom_victims = ATOMIC_INIT(0);
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static DECLARE_WAIT_QUEUE_HEAD(oom_victims_wait);
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bool oom_killer_disabled __read_mostly;
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static DECLARE_RWSEM(oom_sem);
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/**
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* mark_tsk_oom_victim - marks the given taks as OOM victim.
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* @tsk: task to mark
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*
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* Has to be called with oom_sem taken for read and never after
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* oom has been disabled already.
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*/
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void mark_tsk_oom_victim(struct task_struct *tsk)
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{
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WARN_ON(oom_killer_disabled);
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/* OOM killer might race with memcg OOM */
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if (test_and_set_tsk_thread_flag(tsk, TIF_MEMDIE))
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return;
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/*
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* Make sure that the task is woken up from uninterruptible sleep
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* if it is frozen because OOM killer wouldn't be able to free
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* any memory and livelock. freezing_slow_path will tell the freezer
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* that TIF_MEMDIE tasks should be ignored.
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*/
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__thaw_task(tsk);
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atomic_inc(&oom_victims);
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}
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/**
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* unmark_oom_victim - unmarks the current task as OOM victim.
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*
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* Wakes up all waiters in oom_killer_disable()
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*/
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void unmark_oom_victim(void)
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{
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if (!test_and_clear_thread_flag(TIF_MEMDIE))
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return;
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down_read(&oom_sem);
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/*
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* There is no need to signal the lasst oom_victim if there
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* is nobody who cares.
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*/
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if (!atomic_dec_return(&oom_victims) && oom_killer_disabled)
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wake_up_all(&oom_victims_wait);
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up_read(&oom_sem);
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}
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/**
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* oom_killer_disable - disable OOM killer
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*
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* Forces all page allocations to fail rather than trigger OOM killer.
|
|
* Will block and wait until all OOM victims are killed.
|
|
*
|
|
* The function cannot be called when there are runnable user tasks because
|
|
* the userspace would see unexpected allocation failures as a result. Any
|
|
* new usage of this function should be consulted with MM people.
|
|
*
|
|
* Returns true if successful and false if the OOM killer cannot be
|
|
* disabled.
|
|
*/
|
|
bool oom_killer_disable(void)
|
|
{
|
|
/*
|
|
* Make sure to not race with an ongoing OOM killer
|
|
* and that the current is not the victim.
|
|
*/
|
|
down_write(&oom_sem);
|
|
if (test_thread_flag(TIF_MEMDIE)) {
|
|
up_write(&oom_sem);
|
|
return false;
|
|
}
|
|
|
|
oom_killer_disabled = true;
|
|
up_write(&oom_sem);
|
|
|
|
wait_event(oom_victims_wait, !atomic_read(&oom_victims));
|
|
|
|
return true;
|
|
}
|
|
|
|
/**
|
|
* oom_killer_enable - enable OOM killer
|
|
*/
|
|
void oom_killer_enable(void)
|
|
{
|
|
down_write(&oom_sem);
|
|
oom_killer_disabled = false;
|
|
up_write(&oom_sem);
|
|
}
|
|
|
|
#define K(x) ((x) << (PAGE_SHIFT-10))
|
|
/*
|
|
* Must be called while holding a reference to p, which will be released upon
|
|
* returning.
|
|
*/
|
|
void oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
|
|
unsigned int points, unsigned long totalpages,
|
|
struct mem_cgroup *memcg, nodemask_t *nodemask,
|
|
const char *message)
|
|
{
|
|
struct task_struct *victim = p;
|
|
struct task_struct *child;
|
|
struct task_struct *t;
|
|
struct mm_struct *mm;
|
|
unsigned int victim_points = 0;
|
|
static DEFINE_RATELIMIT_STATE(oom_rs, DEFAULT_RATELIMIT_INTERVAL,
|
|
DEFAULT_RATELIMIT_BURST);
|
|
|
|
/*
|
|
* 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
|
|
*/
|
|
task_lock(p);
|
|
if (p->mm && task_will_free_mem(p)) {
|
|
mark_tsk_oom_victim(p);
|
|
task_unlock(p);
|
|
put_task_struct(p);
|
|
return;
|
|
}
|
|
task_unlock(p);
|
|
|
|
if (__ratelimit(&oom_rs))
|
|
dump_header(p, gfp_mask, order, memcg, nodemask);
|
|
|
|
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);
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
read_lock(&tasklist_lock);
|
|
for_each_thread(p, t) {
|
|
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, memcg, nodemask,
|
|
totalpages);
|
|
if (child_points > victim_points) {
|
|
put_task_struct(victim);
|
|
victim = child;
|
|
victim_points = child_points;
|
|
get_task_struct(victim);
|
|
}
|
|
}
|
|
}
|
|
read_unlock(&tasklist_lock);
|
|
|
|
p = find_lock_task_mm(victim);
|
|
if (!p) {
|
|
put_task_struct(victim);
|
|
return;
|
|
} else if (victim != p) {
|
|
get_task_struct(p);
|
|
put_task_struct(victim);
|
|
victim = p;
|
|
}
|
|
|
|
/* mm cannot safely be dereferenced after task_unlock(victim) */
|
|
mm = victim->mm;
|
|
mark_tsk_oom_victim(victim);
|
|
pr_err("Killed process %d (%s) total-vm:%lukB, anon-rss:%lukB, file-rss:%lukB\n",
|
|
task_pid_nr(victim), victim->comm, K(victim->mm->total_vm),
|
|
K(get_mm_counter(victim->mm, MM_ANONPAGES)),
|
|
K(get_mm_counter(victim->mm, MM_FILEPAGES)));
|
|
task_unlock(victim);
|
|
|
|
/*
|
|
* Kill all user processes sharing victim->mm in other thread groups, if
|
|
* any. They don't get access to memory reserves, though, to avoid
|
|
* depletion of all memory. This prevents mm->mmap_sem livelock when an
|
|
* oom killed thread 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.
|
|
*/
|
|
rcu_read_lock();
|
|
for_each_process(p)
|
|
if (p->mm == mm && !same_thread_group(p, victim) &&
|
|
!(p->flags & PF_KTHREAD)) {
|
|
if (p->signal->oom_score_adj == OOM_SCORE_ADJ_MIN)
|
|
continue;
|
|
|
|
task_lock(p); /* Protect ->comm from prctl() */
|
|
pr_err("Kill process %d (%s) sharing same memory\n",
|
|
task_pid_nr(p), p->comm);
|
|
task_unlock(p);
|
|
do_send_sig_info(SIGKILL, SEND_SIG_FORCED, p, true);
|
|
}
|
|
rcu_read_unlock();
|
|
|
|
do_send_sig_info(SIGKILL, SEND_SIG_FORCED, victim, true);
|
|
put_task_struct(victim);
|
|
}
|
|
#undef K
|
|
|
|
/*
|
|
* Determines whether the kernel must panic because of the panic_on_oom sysctl.
|
|
*/
|
|
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;
|
|
}
|
|
dump_header(NULL, gfp_mask, order, NULL, nodemask);
|
|
panic("Out of memory: %s panic_on_oom is enabled\n",
|
|
sysctl_panic_on_oom == 2 ? "compulsory" : "system-wide");
|
|
}
|
|
|
|
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.
|
|
*/
|
|
bool oom_zonelist_trylock(struct zonelist *zonelist, gfp_t gfp_mask)
|
|
{
|
|
struct zoneref *z;
|
|
struct zone *zone;
|
|
bool ret = true;
|
|
|
|
spin_lock(&zone_scan_lock);
|
|
for_each_zone_zonelist(zone, z, zonelist, gfp_zone(gfp_mask))
|
|
if (test_bit(ZONE_OOM_LOCKED, &zone->flags)) {
|
|
ret = false;
|
|
goto out;
|
|
}
|
|
|
|
/*
|
|
* Lock each zone in the zonelist under zone_scan_lock so a parallel
|
|
* call to oom_zonelist_trylock() doesn't succeed when it shouldn't.
|
|
*/
|
|
for_each_zone_zonelist(zone, z, zonelist, gfp_zone(gfp_mask))
|
|
set_bit(ZONE_OOM_LOCKED, &zone->flags);
|
|
|
|
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 oom_zonelist_unlock(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))
|
|
clear_bit(ZONE_OOM_LOCKED, &zone->flags);
|
|
spin_unlock(&zone_scan_lock);
|
|
}
|
|
|
|
/**
|
|
* __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
|
|
* @nodemask: nodemask passed to page allocator
|
|
* @force_kill: true if a task must be killed, even if others are exiting
|
|
*
|
|
* 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.
|
|
*/
|
|
static void __out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask,
|
|
int order, nodemask_t *nodemask, bool force_kill)
|
|
{
|
|
const nodemask_t *mpol_mask;
|
|
struct task_struct *p;
|
|
unsigned long totalpages;
|
|
unsigned long freed = 0;
|
|
unsigned int uninitialized_var(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 current has a pending SIGKILL or is exiting, then automatically
|
|
* select it. The goal is to allow it to allocate so that it may
|
|
* quickly exit and free its memory.
|
|
*
|
|
* But don't select if current has already released its mm and cleared
|
|
* TIF_MEMDIE flag at exit_mm(), otherwise an OOM livelock may occur.
|
|
*/
|
|
if (current->mm &&
|
|
(fatal_signal_pending(current) || task_will_free_mem(current))) {
|
|
mark_tsk_oom_victim(current);
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* Check if there were limitations on the allocation (only relevant for
|
|
* NUMA) that may require different handling.
|
|
*/
|
|
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);
|
|
|
|
if (sysctl_oom_kill_allocating_task && current->mm &&
|
|
!oom_unkillable_task(current, NULL, nodemask) &&
|
|
current->signal->oom_score_adj != OOM_SCORE_ADJ_MIN) {
|
|
get_task_struct(current);
|
|
oom_kill_process(current, gfp_mask, order, 0, totalpages, NULL,
|
|
nodemask,
|
|
"Out of memory (oom_kill_allocating_task)");
|
|
goto out;
|
|
}
|
|
|
|
p = select_bad_process(&points, totalpages, mpol_mask, force_kill);
|
|
/* Found nothing?!?! Either we hang forever, or we panic. */
|
|
if (!p) {
|
|
dump_header(NULL, gfp_mask, order, NULL, mpol_mask);
|
|
panic("Out of memory and no killable processes...\n");
|
|
}
|
|
if (p != (void *)-1UL) {
|
|
oom_kill_process(p, gfp_mask, order, points, totalpages, NULL,
|
|
nodemask, "Out of memory");
|
|
killed = 1;
|
|
}
|
|
out:
|
|
/*
|
|
* Give the killed threads a good chance of exiting before trying to
|
|
* allocate memory again.
|
|
*/
|
|
if (killed)
|
|
schedule_timeout_killable(1);
|
|
}
|
|
|
|
/**
|
|
* out_of_memory - tries to invoke OOM killer.
|
|
* @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
|
|
* @force_kill: true if a task must be killed, even if others are exiting
|
|
*
|
|
* invokes __out_of_memory if the OOM is not disabled by oom_killer_disable()
|
|
* when it returns false. Otherwise returns true.
|
|
*/
|
|
bool out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask,
|
|
int order, nodemask_t *nodemask, bool force_kill)
|
|
{
|
|
bool ret = false;
|
|
|
|
down_read(&oom_sem);
|
|
if (!oom_killer_disabled) {
|
|
__out_of_memory(zonelist, gfp_mask, order, nodemask, force_kill);
|
|
ret = true;
|
|
}
|
|
up_read(&oom_sem);
|
|
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* The pagefault handler calls here because it is out of memory, so kill a
|
|
* memory-hogging task. If any populated zone has ZONE_OOM_LOCKED set, a
|
|
* parallel oom killing is already in progress so do nothing.
|
|
*/
|
|
void pagefault_out_of_memory(void)
|
|
{
|
|
struct zonelist *zonelist;
|
|
|
|
down_read(&oom_sem);
|
|
if (mem_cgroup_oom_synchronize(true))
|
|
goto unlock;
|
|
|
|
zonelist = node_zonelist(first_memory_node, GFP_KERNEL);
|
|
if (oom_zonelist_trylock(zonelist, GFP_KERNEL)) {
|
|
if (!oom_killer_disabled)
|
|
__out_of_memory(NULL, 0, 0, NULL, false);
|
|
else
|
|
/*
|
|
* There shouldn't be any user tasks runable while the
|
|
* OOM killer is disabled so the current task has to
|
|
* be a racing OOM victim for which oom_killer_disable()
|
|
* is waiting for.
|
|
*/
|
|
WARN_ON(test_thread_flag(TIF_MEMDIE));
|
|
|
|
oom_zonelist_unlock(zonelist, GFP_KERNEL);
|
|
}
|
|
unlock:
|
|
up_read(&oom_sem);
|
|
}
|