The patch titled
oom: sacrifice child with highest badness score for parent fix
has been added to the -mm tree. Its filename is
oom-sacrifice-child-with-highest-badness-score-for-parent-fix.patch
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------------------------------------------------------
Subject: oom: sacrifice child with highest badness score for parent fix
From: David Rientjes <rientjes@xxxxxxxxxx>
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>
Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
Cc: Balbir Singh <balbir@xxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/oom_kill.c | 25 +++++++++++++++----------
1 file changed, 15 insertions(+), 10 deletions(-)
diff -puN mm/oom_kill.c~oom-sacrifice-child-with-highest-badness-score-for-parent-fix mm/oom_kill.c
--- a/mm/oom_kill.c~oom-sacrifice-child-with-highest-badness-score-for-parent-fix
+++ a/mm/oom_kill.c
@@ -437,7 +437,7 @@ static int oom_kill_process(struct task_
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;
@@ -459,22 +459,27 @@ static int oom_kill_process(struct task_
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);
_
Patches currently in -mm which might be from rientjes@xxxxxxxxxx are
avr32-invoke-oom-killer-from-page-fault.patch
oom-check-pf_kthread-instead-of-mm-to-skip-kthreads.patch
oom-pf_exiting-check-should-take-mm-into-account.patch
oom-introduce-find_lock_task_mm-to-fix-mm-false-positives.patch
oom-dump_tasks-use-find_lock_task_mm-too.patch
oom-improve-commentary-in-dump_tasks.patch
oom-dump_tasks-use-find_lock_task_mm-too-dump_tasks-use-find_lock_task_mm-too-fix.patch
oom-give-current-access-to-memory-reserves-if-it-has-been-killed.patch
oom-avoid-sending-exiting-tasks-a-sigkill.patch
oom-filter-tasks-not-sharing-the-same-cpuset.patch
oom-sacrifice-child-with-highest-badness-score-for-parent.patch
oom-sacrifice-child-with-highest-badness-score-for-parent-protect-dereferencing-of-tasks-comm.patch
oom-sacrifice-child-with-highest-badness-score-for-parent-fix.patch
oom-select-task-from-tasklist-for-mempolicy-ooms.patch
oom-select-task-from-tasklist-for-mempolicy-ooms-add-has_intersects_mems_allowed-uma-variant.patch
oom-select-task-from-tasklist-for-mempolicy-ooms-introduce-find_lock_task_mm-to-fix-mm-false-positives-fix.patch
oom-enable-oom-tasklist-dump-by-default.patch
oom-avoid-oom-killer-for-lowmem-allocations.patch
oom-extract-panic-helper-function.patch
oom-remove-special-handling-for-pagefault-ooms.patch
oom-move-sysctl-declarations-to-oomh.patch
oom-remove-unnecessary-code-and-cleanup.patch
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