From 2e062600fe2beb07bf5fe1884d91d576a21ce714 Mon Sep 17 00:00:00 2001 From: will Date: Sat, 24 Jan 2015 17:32:45 +0000 Subject: [PATCH] Add vm.panic_on_oom sysctl, which enables those who would rather panic than kill a process, when the system runs out of memory. Defaults to off. Usually, this is most useful when the OOM condition is due to mismanagement of memory, on a system where the applications in question don't respond well to being killed. In theory, if the system is properly managed, it shouldn't be possible to hit this condition. If it does, the panic can be more desirable for some users (since it can be a good means of finding the root cause) rather than killing the largest process and continuing on its merry way. As kib@ mentions in the differential, there is also protect(1), which uses procctl(PROC_SPROTECT) to ensure that some processes are immune. However, a panic approach is still useful in some environments. This is primarily intended as a development/debugging tool. Differential Revision: D1627 Reviewed by: kib MFC after: 1 week --- sys/vm/vm_pageout.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/sys/vm/vm_pageout.c b/sys/vm/vm_pageout.c index c81290ca097d..ecc3dabfe70f 100644 --- a/sys/vm/vm_pageout.c +++ b/sys/vm/vm_pageout.c @@ -180,6 +180,12 @@ static int vm_swap_enabled = 1; static int vm_swap_idle_enabled = 0; #endif +static int vm_panic_on_oom = 0; + +SYSCTL_INT(_vm, OID_AUTO, panic_on_oom, + CTLFLAG_RWTUN, &vm_panic_on_oom, 0, + "panic on out of memory instead of killing the largest process"); + SYSCTL_INT(_vm, OID_AUTO, pageout_wakeup_thresh, CTLFLAG_RW, &vm_pageout_wakeup_thresh, 0, "free page threshold for waking up the pageout daemon"); @@ -1585,6 +1591,8 @@ vm_pageout_oom(int shortage) } sx_sunlock(&allproc_lock); if (bigproc != NULL) { + if (vm_panic_on_oom != 0) + panic("out of swap space"); PROC_LOCK(bigproc); killproc(bigproc, "out of swap space"); sched_nice(bigproc, PRIO_MIN);