X-Git-Url: http://ftp.safe.ca/?a=blobdiff_plain;f=mm%2Foom_kill.c;h=2e3ce3a928b97dd8eeb54b42fb6f363d15a6d2ae;hb=450efcfd2e1d941e302a8c89322fbfcef237be98;hp=b9af136e5cfa7c7e7a23cb40f25d60b11f9b11a5;hpb=36c8b586896f60cb91a4fd526233190b34316baf;p=safe%2Fjmp%2Flinux-2.6 diff --git a/mm/oom_kill.c b/mm/oom_kill.c index b9af136..2e3ce3a 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -15,12 +15,15 @@ * kernel subsystems and hints as to where to find out what things do. */ +#include #include #include #include #include #include #include +#include +#include int sysctl_panic_on_oom; /* #define DEBUG */ @@ -58,6 +61,12 @@ unsigned long badness(struct task_struct *p, unsigned long uptime) } /* + * swapoff can easily use up all memory, so kill those first. + */ + if (p->flags & PF_SWAPOFF) + return ULONG_MAX; + + /* * The memory size of the process is the basis for the badness. */ points = mm->total_vm; @@ -127,6 +136,14 @@ unsigned long badness(struct task_struct *p, unsigned long uptime) 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_excl_nodes_overlap(p)) + points /= 8; + + /* * Adjust the score by oomkilladj. */ if (p->oomkilladj) { @@ -161,8 +178,7 @@ static inline int constrained_alloc(struct zonelist *zonelist, gfp_t gfp_mask) for (z = zonelist->zones; *z; z++) if (cpuset_zone_allowed(*z, gfp_mask)) - node_clear((*z)->zone_pgdat->node_id, - nodes); + node_clear(zone_to_nid(*z), nodes); else return CONSTRAINT_CPUSET; @@ -189,27 +205,49 @@ static struct task_struct *select_bad_process(unsigned long *ppoints) do_posix_clock_monotonic_gettime(&uptime); do_each_thread(g, p) { unsigned long points; - int releasing; - /* skip the init task with pid == 1 */ - if (p->pid == 1) - continue; - if (p->oomkilladj == OOM_DISABLE) + /* + * skip kernel threads and tasks which have already released + * their mm. + */ + if (!p->mm) continue; - /* If p's nodes don't overlap ours, it won't help to kill p. */ - if (!cpuset_excl_nodes_overlap(p)) + /* skip the init task */ + if (is_init(p)) 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. */ - releasing = test_tsk_thread_flag(p, TIF_MEMDIE) || - p->flags & PF_EXITING; - if (releasing && !(p->flags & PF_DEAD)) - return ERR_PTR(-1UL); - if (p->flags & PF_SWAPOFF) - return p; + if (p->flags & PF_EXITING) { + if (p != current) + return ERR_PTR(-1UL); + + chosen = p; + *ppoints = ULONG_MAX; + } + + if (p->oomkilladj == OOM_DISABLE) + continue; points = badness(p, uptime.tv_sec); if (points > *ppoints || !chosen) { @@ -217,32 +255,33 @@ static struct task_struct *select_bad_process(unsigned long *ppoints) *ppoints = points; } } while_each_thread(g, p); + return chosen; } /** - * We must be careful though to never send SIGKILL a process with - * CAP_SYS_RAW_IO set, send SIGTERM instead (but it's unlikely that - * we select a process with CAP_SYS_RAW_IO set). + * 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, const char *message) { - if (p->pid == 1) { + if (is_init(p)) { WARN_ON(1); printk(KERN_WARNING "tried to kill init!\n"); return; } - task_lock(p); - if (!p->mm || p->mm == &init_mm) { + if (!p->mm) { WARN_ON(1); printk(KERN_WARNING "tried to kill an mm-less task!\n"); - task_unlock(p); return; } - task_unlock(p); - printk(KERN_ERR "%s: Killed process %d (%s).\n", + + if (message) { + printk(KERN_ERR "%s: Killed process %d (%s).\n", message, p->pid, p->comm); + } /* * We give our sacrificial lamb high priority and access to @@ -271,7 +310,7 @@ static int oom_kill_task(struct task_struct *p, const char *message) * However, this is of no concern to us. */ - if (mm == NULL || mm == &init_mm) + if (mm == NULL) return 1; __oom_kill_task(p, message); @@ -293,8 +332,17 @@ static int oom_kill_process(struct task_struct *p, unsigned long points, struct task_struct *c; struct list_head *tsk; - printk(KERN_ERR "Out of Memory: Kill process %d (%s) score %li and " - "children.\n", p->pid, p->comm, points); + /* + * 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, NULL); + return 0; + } + + printk(KERN_ERR "Out of Memory: Kill process %d (%s) score %li" + " and children.\n", p->pid, p->comm, points); /* Try to kill a child first */ list_for_each(tsk, &p->children) { c = list_entry(tsk, struct task_struct, sibling); @@ -306,6 +354,20 @@ static int oom_kill_process(struct task_struct *p, unsigned long points, return oom_kill_task(p, message); } +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); + /** * out_of_memory - kill the "best" process when we run out of memory * @@ -318,10 +380,17 @@ void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask, int order) { struct task_struct *p; unsigned long points = 0; + 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 (printk_ratelimit()) { - printk("oom-killer: gfp_mask=0x%x, order=%d\n", - gfp_mask, order); + printk(KERN_WARNING "%s invoked oom-killer: " + "gfp_mask=0x%x, order=%d, oomkilladj=%d\n", + current->comm, gfp_mask, order, current->oomkilladj); dump_stack(); show_mem(); }