diff options
Diffstat (limited to 'mm/oom_kill.c')
| -rw-r--r-- | mm/oom_kill.c | 76 |
1 files changed, 53 insertions, 23 deletions
diff --git a/mm/oom_kill.c b/mm/oom_kill.c index 1ecc0bcaecc5..d13a33918fa2 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -118,6 +118,15 @@ found: return t; } +/* + * order == -1 means the oom kill is required by sysrq, otherwise only + * for display purposes. + */ +static inline bool is_sysrq_oom(struct oom_control *oc) +{ + return oc->order == -1; +} + /* return true if the task is not adequate as candidate victim task. */ static bool oom_unkillable_task(struct task_struct *p, struct mem_cgroup *memcg, const nodemask_t *nodemask) @@ -265,7 +274,7 @@ enum oom_scan_t oom_scan_process_thread(struct oom_control *oc, * Don't allow any other task to have access to the reserves. */ if (test_tsk_thread_flag(task, TIF_MEMDIE)) { - if (oc->order != -1) + if (!is_sysrq_oom(oc)) return OOM_SCAN_ABORT; } if (!task->mm) @@ -278,7 +287,7 @@ enum oom_scan_t oom_scan_process_thread(struct oom_control *oc, if (oom_task_origin(task)) return OOM_SCAN_SELECT; - if (task_will_free_mem(task) && oc->order != -1) + if (task_will_free_mem(task) && !is_sysrq_oom(oc)) return OOM_SCAN_ABORT; return OOM_SCAN_OK; @@ -377,13 +386,11 @@ static void dump_tasks(struct mem_cgroup *memcg, const nodemask_t *nodemask) static void dump_header(struct oom_control *oc, struct task_struct *p, struct mem_cgroup *memcg) { - task_lock(current); pr_warning("%s invoked oom-killer: gfp_mask=0x%x, order=%d, " "oom_score_adj=%hd\n", current->comm, oc->gfp_mask, oc->order, current->signal->oom_score_adj); - cpuset_print_task_mems_allowed(current); - task_unlock(current); + cpuset_print_current_mems_allowed(); dump_stack(); if (memcg) mem_cgroup_print_oom_info(memcg, p); @@ -476,6 +483,24 @@ void oom_killer_enable(void) oom_killer_disabled = false; } +/* + * task->mm can be NULL if the task is the exited group leader. So to + * determine whether the task is using a particular mm, we examine all the + * task's threads: if one of those is using this mm then this task was also + * using it. + */ +static bool process_shares_mm(struct task_struct *p, struct mm_struct *mm) +{ + struct task_struct *t; + + for_each_thread(p, t) { + struct mm_struct *t_mm = READ_ONCE(t->mm); + if (t_mm) + return t_mm == mm; + } + return false; +} + #define K(x) ((x) << (PAGE_SHIFT-10)) /* * Must be called while holding a reference to p, which will be released upon @@ -509,10 +534,8 @@ void oom_kill_process(struct oom_control *oc, struct task_struct *p, if (__ratelimit(&oom_rs)) dump_header(oc, p, memcg); - task_lock(p); pr_err("%s: Kill process %d (%s) score %u 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, @@ -525,7 +548,7 @@ void oom_kill_process(struct oom_control *oc, struct task_struct *p, list_for_each_entry(child, &t->children, sibling) { unsigned int child_points; - if (child->mm == p->mm) + if (process_shares_mm(child, p->mm)) continue; /* * oom_badness() returns 0 if the thread is unkillable @@ -552,8 +575,15 @@ void oom_kill_process(struct oom_control *oc, struct task_struct *p, victim = p; } - /* mm cannot safely be dereferenced after task_unlock(victim) */ + /* Get a reference to safely compare mm after task_unlock(victim) */ mm = victim->mm; + atomic_inc(&mm->mm_count); + /* + * We should send SIGKILL before setting TIF_MEMDIE in order to prevent + * the OOM victim from depleting the memory reserves from the user + * space under its control. + */ + do_send_sig_info(SIGKILL, SEND_SIG_FORCED, victim, true); mark_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), @@ -571,21 +601,21 @@ void oom_kill_process(struct oom_control *oc, struct task_struct *p, * 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; + for_each_process(p) { + if (!process_shares_mm(p, mm)) + continue; + if (same_thread_group(p, victim)) + continue; + if (unlikely(p->flags & PF_KTHREAD)) + continue; + 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); - } + do_send_sig_info(SIGKILL, SEND_SIG_FORCED, p, true); + } rcu_read_unlock(); - do_send_sig_info(SIGKILL, SEND_SIG_FORCED, victim, true); + mmdrop(mm); put_task_struct(victim); } #undef K @@ -608,7 +638,7 @@ void check_panic_on_oom(struct oom_control *oc, enum oom_constraint constraint, return; } /* Do not panic for oom kills triggered by sysrq */ - if (oc->order == -1) + if (is_sysrq_oom(oc)) return; dump_header(oc, NULL, memcg); panic("Out of memory: %s panic_on_oom is enabled\n", @@ -688,7 +718,7 @@ bool out_of_memory(struct oom_control *oc) p = select_bad_process(oc, &points, totalpages); /* Found nothing?!?! Either we hang forever, or we panic. */ - if (!p && oc->order != -1) { + if (!p && !is_sysrq_oom(oc)) { dump_header(oc, NULL, NULL); panic("Out of memory and no killable processes...\n"); } |