From 8bc719d3cab8414938f9ea6e33b58d8810d18068 Mon Sep 17 00:00:00 2001 From: Martin Schwidefsky Date: Mon, 25 Sep 2006 23:31:20 -0700 Subject: [PATCH] out of memory notifier Add a notifer chain to the out of memory killer. If one of the registered callbacks could release some memory, do not kill the process but return and retry the allocation that forced the oom killer to run. The purpose of the notifier is to add a safety net in the presence of memory ballooners. If the resource manager inflated the balloon to a size where memory allocations can not be satisfied anymore, it is better to deflate the balloon a bit instead of killing processes. The implementation for the s390 ballooner is included. [akpm@osdl.org: cleanups] Signed-off-by: Martin Schwidefsky Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/oom_kill.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) (limited to 'mm') diff --git a/mm/oom_kill.c b/mm/oom_kill.c index b9af136e5cfa..7d056843fa2d 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -21,6 +21,8 @@ #include #include #include +#include +#include int sysctl_panic_on_oom; /* #define DEBUG */ @@ -306,6 +308,20 @@ 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 * @@ -318,6 +334,12 @@ 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", -- cgit v1.2.2