[PATCH] mm, oom: fix oom_unkillable_task for memcg OOMs
From: Shakeel Butt
Date: Mon Jun 17 2019 - 12:04:59 EST
Currently oom_unkillable_task() checks mems_allowed even for memcg OOMs
which does not make sense as memcg OOMs can not be triggered due to
numa constraints. Fixing that.
Also if memcg is given, oom_unkillable_task() will check the task's
memcg membership as well to detect oom killability. However all the
memcg related code paths leading to oom_unkillable_task(), other than
dump_tasks(), come through mem_cgroup_scan_tasks() which traverses
tasks through memcgs. Once dump_tasks() is converted to use
mem_cgroup_scan_tasks(), there is no need to do memcg membership check
in oom_unkillable_task().
Signed-off-by: Shakeel Butt <shakeelb@xxxxxxxxxx>
---
fs/proc/base.c | 3 +-
include/linux/oom.h | 3 +-
mm/oom_kill.c | 100 +++++++++++++++++++++++++-------------------
3 files changed, 60 insertions(+), 46 deletions(-)
diff --git a/fs/proc/base.c b/fs/proc/base.c
index b8d5d100ed4a..69b0d1b6583d 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -532,8 +532,7 @@ static int proc_oom_score(struct seq_file *m, struct pid_namespace *ns,
unsigned long totalpages = totalram_pages() + total_swap_pages;
unsigned long points = 0;
- points = oom_badness(task, NULL, NULL, totalpages) *
- 1000 / totalpages;
+ points = oom_badness(task, NULL, totalpages) * 1000 / totalpages;
seq_printf(m, "%lu\n", points);
return 0;
diff --git a/include/linux/oom.h b/include/linux/oom.h
index d07992009265..39c42caa3231 100644
--- a/include/linux/oom.h
+++ b/include/linux/oom.h
@@ -108,8 +108,7 @@ static inline vm_fault_t check_stable_address_space(struct mm_struct *mm)
bool __oom_reap_task_mm(struct mm_struct *mm);
extern unsigned long oom_badness(struct task_struct *p,
- struct mem_cgroup *memcg, const nodemask_t *nodemask,
- unsigned long totalpages);
+ struct oom_control *oc, unsigned long totalpages);
extern bool out_of_memory(struct oom_control *oc);
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 05aaa1a5920b..47ded0e07e98 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -152,20 +152,25 @@ static inline bool is_memcg_oom(struct oom_control *oc)
}
/* return true if the task is not adequate as candidate victim task. */
-static bool oom_unkillable_task(struct task_struct *p,
- struct mem_cgroup *memcg, const nodemask_t *nodemask)
+static bool oom_unkillable_task(struct task_struct *p, struct oom_control *oc)
{
if (is_global_init(p))
return true;
if (p->flags & PF_KTHREAD)
return true;
+ if (!oc)
+ return false;
- /* When mem_cgroup_out_of_memory() and p is not member of the group */
- if (memcg && !task_in_mem_cgroup(p, memcg))
- return true;
+ /*
+ * For memcg OOM, we reach here through mem_cgroup_scan_tasks(), no
+ * need to check p's membership. Also the following checks are
+ * irrelevant to memcg OOMs.
+ */
+ if (is_memcg_oom(oc))
+ return false;
/* p may not have freeable memory in nodemask */
- if (!has_intersects_mems_allowed(p, nodemask))
+ if (!has_intersects_mems_allowed(p, oc->nodemask))
return true;
return false;
@@ -193,21 +198,20 @@ static bool is_dump_unreclaim_slabs(void)
/**
* oom_badness - heuristic function to determine which candidate task to kill
* @p: task struct of which task we should calculate
+ * @oc: pointer to struct oom_control
* @totalpages: total present RAM allowed for page allocation
- * @memcg: task's memory controller, if constrained
- * @nodemask: nodemask passed to page allocator for mempolicy ooms
*
* The heuristic for determining which task to kill is made to be as simple and
* predictable as possible. The goal is to return the highest value for the
* task consuming the most memory to avoid subsequent oom failures.
*/
-unsigned long oom_badness(struct task_struct *p, struct mem_cgroup *memcg,
- const nodemask_t *nodemask, unsigned long totalpages)
+unsigned long oom_badness(struct task_struct *p, struct oom_control *oc,
+ unsigned long totalpages)
{
long points;
long adj;
- if (oom_unkillable_task(p, memcg, nodemask))
+ if (oom_unkillable_task(p, oc))
return 0;
p = find_lock_task_mm(p);
@@ -318,7 +322,7 @@ static int oom_evaluate_task(struct task_struct *task, void *arg)
struct oom_control *oc = arg;
unsigned long points;
- if (oom_unkillable_task(task, NULL, oc->nodemask))
+ if (oom_unkillable_task(task, oc))
goto next;
/*
@@ -342,7 +346,7 @@ static int oom_evaluate_task(struct task_struct *task, void *arg)
goto select;
}
- points = oom_badness(task, NULL, oc->nodemask, oc->totalpages);
+ points = oom_badness(task, oc, oc->totalpages);
if (!points || points < oc->chosen_points)
goto next;
@@ -385,10 +389,38 @@ static void select_bad_process(struct oom_control *oc)
oc->chosen_points = oc->chosen_points * 1000 / oc->totalpages;
}
+static int dump_task(struct task_struct *p, void *arg)
+{
+ struct oom_control *oc = arg;
+ struct task_struct *task;
+
+ if (oom_unkillable_task(p, oc))
+ return 0;
+
+ task = find_lock_task_mm(p);
+ if (!task) {
+ /*
+ * This is a kthread or all of p's threads have already
+ * detached their mm's. There's no need to report
+ * them; they can't be oom killed anyway.
+ */
+ return 0;
+ }
+
+ pr_info("[%7d] %5d %5d %8lu %8lu %8ld %8lu %5hd %s\n",
+ task->pid, from_kuid(&init_user_ns, task_uid(task)),
+ task->tgid, task->mm->total_vm, get_mm_rss(task->mm),
+ mm_pgtables_bytes(task->mm),
+ get_mm_counter(task->mm, MM_SWAPENTS),
+ task->signal->oom_score_adj, task->comm);
+ task_unlock(task);
+
+ return 0;
+}
+
/**
* dump_tasks - dump current memory state of all system tasks
- * @memcg: current's memory controller, if constrained
- * @nodemask: nodemask passed to page allocator for mempolicy ooms
+ * @oc: pointer to struct oom_control
*
* Dumps the current memory state of all eligible tasks. Tasks not in the same
* memcg, not in the same cpuset, or bound to a disjoint set of mempolicy nodes
@@ -396,37 +428,21 @@ static void select_bad_process(struct oom_control *oc)
* State information includes task's pid, uid, tgid, vm size, rss,
* pgtables_bytes, swapents, oom_score_adj value, and name.
*/
-static void dump_tasks(struct mem_cgroup *memcg, const nodemask_t *nodemask)
+static void dump_tasks(struct oom_control *oc)
{
- struct task_struct *p;
- struct task_struct *task;
-
pr_info("Tasks state (memory values in pages):\n");
pr_info("[ pid ] uid tgid total_vm rss pgtables_bytes swapents oom_score_adj name\n");
- rcu_read_lock();
- for_each_process(p) {
- if (oom_unkillable_task(p, memcg, nodemask))
- continue;
- task = find_lock_task_mm(p);
- if (!task) {
- /*
- * This is a kthread or all of p's threads have already
- * detached their mm's. There's no need to report
- * them; they can't be oom killed anyway.
- */
- continue;
- }
+ if (is_memcg_oom(oc))
+ mem_cgroup_scan_tasks(oc->memcg, dump_task, oc);
+ else {
+ struct task_struct *p;
- pr_info("[%7d] %5d %5d %8lu %8lu %8ld %8lu %5hd %s\n",
- task->pid, from_kuid(&init_user_ns, task_uid(task)),
- task->tgid, task->mm->total_vm, get_mm_rss(task->mm),
- mm_pgtables_bytes(task->mm),
- get_mm_counter(task->mm, MM_SWAPENTS),
- task->signal->oom_score_adj, task->comm);
- task_unlock(task);
+ rcu_read_lock();
+ for_each_process(p)
+ dump_task(p, oc);
+ rcu_read_unlock();
}
- rcu_read_unlock();
}
static void dump_oom_summary(struct oom_control *oc, struct task_struct *victim)
@@ -458,7 +474,7 @@ static void dump_header(struct oom_control *oc, struct task_struct *p)
dump_unreclaimable_slab();
}
if (sysctl_oom_dump_tasks)
- dump_tasks(oc->memcg, oc->nodemask);
+ dump_tasks(oc);
if (p)
dump_oom_summary(oc, p);
}
@@ -1078,7 +1094,7 @@ bool out_of_memory(struct oom_control *oc)
check_panic_on_oom(oc, constraint);
if (!is_memcg_oom(oc) && sysctl_oom_kill_allocating_task &&
- current->mm && !oom_unkillable_task(current, NULL, oc->nodemask) &&
+ current->mm && !oom_unkillable_task(current, oc) &&
current->signal->oom_score_adj != OOM_SCORE_ADJ_MIN) {
get_task_struct(current);
oc->chosen = current;
--
2.22.0.410.gd8fdbe21b5-goog