Elaborate on the comment in oom_kill_process() so it's clear why a
killable child with a different mm is sacrificied for its parent.
At the same time, rename auto variable `c' to "child" and move "cpoints"
inside the list_for_each_entry() loop with a more descriptive name as
akpm suggests.
Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx>
---
mm/oom_kill.c | 25 +++++++++++++++----------
1 files changed, 15 insertions(+), 10 deletions(-)
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -440,7 +440,7 @@ static int oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
const char *message)
{
struct task_struct *victim = p;
- struct task_struct *c;
+ struct task_struct *child;
struct task_struct *t = p;
unsigned long victim_points = 0;
struct timespec uptime;
@@ -462,22 +462,27 @@ static int oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
message, task_pid_nr(p), p->comm, points);
task_unlock(p);
- /* Try to sacrifice the worst child first */
+ /*
+ * If any of p's children has a different mm and is eligible for kill,
+ * the one with the highest badness() score is sacrificed for its
+ * parent. This attempts to lose the minimal amount of work done while
+ * still freeing memory.
+ */
do_posix_clock_monotonic_gettime(&uptime);
do {
- unsigned long cpoints;
+ list_for_each_entry(child, &t->children, sibling) {
+ unsigned long child_points;
- list_for_each_entry(c, &t->children, sibling) {
- if (c->mm == p->mm)
+ if (child->mm == p->mm)
continue;
- if (mem && !task_in_mem_cgroup(c, mem))
+ if (mem && !task_in_mem_cgroup(child, mem))
continue;
/* badness() returns 0 if the thread is unkillable */
- cpoints = badness(c, uptime.tv_sec);
- if (cpoints > victim_points) {
- victim = c;
- victim_points = cpoints;
+ child_points = badness(child, uptime.tv_sec);
+ if (child_points > victim_points) {
+ victim = child;
+ victim_points = child_points;
}
}
} while_each_thread(p, t);
--
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