Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
new file mode 100644
index 0000000..9595a0f
--- /dev/null
+++ b/mm/oom_kill.c
@@ -0,0 +1,292 @@
+/*
+ * linux/mm/oom_kill.c
+ *
+ * Copyright (C) 1998,2000 Rik van Riel
+ * Thanks go out to Claus Fischer for some serious inspiration and
+ * for goading me into coding this file...
+ *
+ * The routines in this file are used to kill a process when
+ * we're seriously out of memory. This gets called from kswapd()
+ * in linux/mm/vmscan.c when we really run out of memory.
+ *
+ * Since we won't call these routines often (on a well-configured
+ * machine) this file will double as a 'coding guide' and a signpost
+ * for newbie kernel hackers. It features several pointers to major
+ * kernel subsystems and hints as to where to find out what things do.
+ */
+
+#include <linux/mm.h>
+#include <linux/sched.h>
+#include <linux/swap.h>
+#include <linux/timex.h>
+#include <linux/jiffies.h>
+
+/* #define DEBUG */
+
+/**
+ * oom_badness - calculate a numeric value for how bad this task has been
+ * @p: task struct of which task we should calculate
+ * @p: current uptime in seconds
+ *
+ * The formula used is relatively simple and documented inline in the
+ * function. The main rationale is that we want to select a good task
+ * to kill when we run out of memory.
+ *
+ * Good in this context means that:
+ * 1) we lose the minimum amount of work done
+ * 2) we recover a large amount of memory
+ * 3) we don't kill anything innocent of eating tons of memory
+ * 4) we want to kill the minimum amount of processes (one)
+ * 5) we try to kill the process the user expects us to kill, this
+ * algorithm has been meticulously tuned to meet the principle
+ * of least surprise ... (be careful when you change it)
+ */
+
+unsigned long badness(struct task_struct *p, unsigned long uptime)
+{
+ unsigned long points, cpu_time, run_time, s;
+ struct list_head *tsk;
+
+ if (!p->mm)
+ return 0;
+
+ /*
+ * The memory size of the process is the basis for the badness.
+ */
+ points = p->mm->total_vm;
+
+ /*
+ * Processes which fork a lot of child processes are likely
+ * a good choice. We add the vmsize of the childs if they
+ * have an own mm. This prevents forking servers to flood the
+ * machine with an endless amount of childs
+ */
+ list_for_each(tsk, &p->children) {
+ struct task_struct *chld;
+ chld = list_entry(tsk, struct task_struct, sibling);
+ if (chld->mm != p->mm && chld->mm)
+ points += chld->mm->total_vm;
+ }
+
+ /*
+ * CPU time is in tens of seconds and run time is in thousands
+ * of seconds. There is no particular reason for this other than
+ * that it turned out to work very well in practice.
+ */
+ cpu_time = (cputime_to_jiffies(p->utime) + cputime_to_jiffies(p->stime))
+ >> (SHIFT_HZ + 3);
+
+ if (uptime >= p->start_time.tv_sec)
+ run_time = (uptime - p->start_time.tv_sec) >> 10;
+ else
+ run_time = 0;
+
+ s = int_sqrt(cpu_time);
+ if (s)
+ points /= s;
+ s = int_sqrt(int_sqrt(run_time));
+ if (s)
+ points /= s;
+
+ /*
+ * Niced processes are most likely less important, so double
+ * their badness points.
+ */
+ if (task_nice(p) > 0)
+ points *= 2;
+
+ /*
+ * Superuser processes are usually more important, so we make it
+ * less likely that we kill those.
+ */
+ if (cap_t(p->cap_effective) & CAP_TO_MASK(CAP_SYS_ADMIN) ||
+ p->uid == 0 || p->euid == 0)
+ points /= 4;
+
+ /*
+ * We don't want to kill a process with direct hardware access.
+ * Not only could that mess up the hardware, but usually users
+ * tend to only have this flag set on applications they think
+ * of as important.
+ */
+ if (cap_t(p->cap_effective) & CAP_TO_MASK(CAP_SYS_RAWIO))
+ points /= 4;
+
+ /*
+ * Adjust the score by oomkilladj.
+ */
+ if (p->oomkilladj) {
+ if (p->oomkilladj > 0)
+ points <<= p->oomkilladj;
+ else
+ points >>= -(p->oomkilladj);
+ }
+
+#ifdef DEBUG
+ printk(KERN_DEBUG "OOMkill: task %d (%s) got %d points\n",
+ p->pid, p->comm, points);
+#endif
+ return points;
+}
+
+/*
+ * Simple selection loop. We chose the process with the highest
+ * number of 'points'. We expect the caller will lock the tasklist.
+ *
+ * (not docbooked, we don't want this one cluttering up the manual)
+ */
+static struct task_struct * select_bad_process(void)
+{
+ unsigned long maxpoints = 0;
+ struct task_struct *g, *p;
+ struct task_struct *chosen = NULL;
+ struct timespec uptime;
+
+ do_posix_clock_monotonic_gettime(&uptime);
+ do_each_thread(g, p)
+ /* skip the init task with pid == 1 */
+ if (p->pid > 1) {
+ unsigned long points;
+
+ /*
+ * This is in the process of releasing memory so wait it
+ * to finish before killing some other task by mistake.
+ */
+ if ((unlikely(test_tsk_thread_flag(p, TIF_MEMDIE)) || (p->flags & PF_EXITING)) &&
+ !(p->flags & PF_DEAD))
+ return ERR_PTR(-1UL);
+ if (p->flags & PF_SWAPOFF)
+ return p;
+
+ points = badness(p, uptime.tv_sec);
+ if (points > maxpoints || !chosen) {
+ chosen = p;
+ maxpoints = 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).
+ */
+static void __oom_kill_task(task_t *p)
+{
+ if (p->pid == 1) {
+ WARN_ON(1);
+ printk(KERN_WARNING "tried to kill init!\n");
+ return;
+ }
+
+ task_lock(p);
+ if (!p->mm || p->mm == &init_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 "Out of Memory: Killed process %d (%s).\n", p->pid, p->comm);
+
+ /*
+ * We give our sacrificial lamb high priority and access to
+ * all the memory it needs. That way it should be able to
+ * exit() and clear out its resources quickly...
+ */
+ p->time_slice = HZ;
+ set_tsk_thread_flag(p, TIF_MEMDIE);
+
+ force_sig(SIGKILL, p);
+}
+
+static struct mm_struct *oom_kill_task(task_t *p)
+{
+ struct mm_struct *mm = get_task_mm(p);
+ task_t * g, * q;
+
+ if (!mm)
+ return NULL;
+ if (mm == &init_mm) {
+ mmput(mm);
+ return NULL;
+ }
+
+ __oom_kill_task(p);
+ /*
+ * kill all processes that share the ->mm (i.e. all threads),
+ * but are in a different thread group
+ */
+ do_each_thread(g, q)
+ if (q->mm == mm && q->tgid != p->tgid)
+ __oom_kill_task(q);
+ while_each_thread(g, q);
+
+ return mm;
+}
+
+static struct mm_struct *oom_kill_process(struct task_struct *p)
+{
+ struct mm_struct *mm;
+ struct task_struct *c;
+ struct list_head *tsk;
+
+ /* Try to kill a child first */
+ list_for_each(tsk, &p->children) {
+ c = list_entry(tsk, struct task_struct, sibling);
+ if (c->mm == p->mm)
+ continue;
+ mm = oom_kill_task(c);
+ if (mm)
+ return mm;
+ }
+ return oom_kill_task(p);
+}
+
+/**
+ * oom_kill - kill the "best" process when we run out of memory
+ *
+ * If we run out of memory, we have the choice between either
+ * killing a random task (bad), letting the system crash (worse)
+ * OR try to be smart about which process to kill. Note that we
+ * don't have to be perfect here, we just have to be good.
+ */
+void out_of_memory(unsigned int __nocast gfp_mask)
+{
+ struct mm_struct *mm = NULL;
+ task_t * p;
+
+ read_lock(&tasklist_lock);
+retry:
+ p = select_bad_process();
+
+ if (PTR_ERR(p) == -1UL)
+ goto out;
+
+ /* Found nothing?!?! Either we hang forever, or we panic. */
+ if (!p) {
+ read_unlock(&tasklist_lock);
+ show_free_areas();
+ panic("Out of memory and no killable processes...\n");
+ }
+
+ printk("oom-killer: gfp_mask=0x%x\n", gfp_mask);
+ show_free_areas();
+ mm = oom_kill_process(p);
+ if (!mm)
+ goto retry;
+
+ out:
+ read_unlock(&tasklist_lock);
+ if (mm)
+ mmput(mm);
+
+ /*
+ * Give "p" a good chance of killing itself before we
+ * retry to allocate memory.
+ */
+ __set_current_state(TASK_INTERRUPTIBLE);
+ schedule_timeout(1);
+}