diff options
| -rw-r--r-- | mm/oom_kill.c | 111 |
1 files changed, 65 insertions, 46 deletions
diff --git a/mm/oom_kill.c b/mm/oom_kill.c index e6c10640e56b..f8eba9651c0c 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -288,6 +288,59 @@ static enum oom_constraint constrained_alloc(struct zonelist *zonelist, } #endif +enum oom_scan_t { + OOM_SCAN_OK, /* scan thread and find its badness */ + OOM_SCAN_CONTINUE, /* do not consider thread for oom kill */ + OOM_SCAN_ABORT, /* abort the iteration and return */ + OOM_SCAN_SELECT, /* always select this thread first */ +}; + +static enum oom_scan_t oom_scan_process_thread(struct task_struct *task, + struct mem_cgroup *memcg, unsigned long totalpages, + const nodemask_t *nodemask, bool force_kill) +{ + if (task->exit_state) + return OOM_SCAN_CONTINUE; + if (oom_unkillable_task(task, memcg, nodemask)) + return OOM_SCAN_CONTINUE; + + /* + * This task already has access to memory reserves and is being killed. + * Don't allow any other task to have access to the reserves. + */ + if (test_tsk_thread_flag(task, TIF_MEMDIE)) { + if (unlikely(frozen(task))) + __thaw_task(task); + if (!force_kill) + return OOM_SCAN_ABORT; + } + if (!task->mm) + return OOM_SCAN_CONTINUE; + + if (task->flags & PF_EXITING) { + /* + * If task is current and is in the process of releasing memory, + * allow the "kill" to set TIF_MEMDIE, which will allow it to + * access memory reserves. Otherwise, it may stall forever. + * + * The iteration isn't broken here, however, in case other + * threads are found to have already been oom killed. + */ + if (task == current) + return OOM_SCAN_SELECT; + else if (!force_kill) { + /* + * If this task is not being ptraced on exit, then wait + * for it to finish before killing some other task + * unnecessarily. + */ + if (!(task->group_leader->ptrace & PT_TRACE_EXIT)) + return OOM_SCAN_ABORT; + } + } + return OOM_SCAN_OK; +} + /* * Simple selection loop. We chose the process with the highest * number of 'points'. We expect the caller will lock the tasklist. @@ -305,53 +358,19 @@ static struct task_struct *select_bad_process(unsigned int *ppoints, do_each_thread(g, p) { unsigned int points; - if (p->exit_state) - continue; - if (oom_unkillable_task(p, memcg, nodemask)) - 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)) { - if (unlikely(frozen(p))) - __thaw_task(p); - if (!force_kill) - return ERR_PTR(-1UL); - } - if (!p->mm) + switch (oom_scan_process_thread(p, memcg, totalpages, nodemask, + force_kill)) { + case OOM_SCAN_SELECT: + chosen = p; + chosen_points = ULONG_MAX; + /* fall through */ + case OOM_SCAN_CONTINUE: continue; - - if (p->flags & PF_EXITING) { - /* - * 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; - chosen_points = ULONG_MAX; - } else if (!force_kill) { - /* - * 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); - } - } - + case OOM_SCAN_ABORT: + return ERR_PTR(-1UL); + case OOM_SCAN_OK: + break; + }; points = oom_badness(p, memcg, nodemask, totalpages); if (points > chosen_points) { chosen = p; |