oom: extract panic helper function
There are various points in the oom killer where the kernel must determine
whether to panic or not. It's better to extract this to a helper function
to remove all the confusion as to its semantics.
Also fix a call to dump_header() where tasklist_lock is not read- locked,
as required.
There's no functional change with this patch.
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/oom.h b/include/linux/oom.h
index 5376623..3ae6d94 100644
--- a/include/linux/oom.h
+++ b/include/linux/oom.h
@@ -22,6 +22,7 @@
CONSTRAINT_NONE,
CONSTRAINT_CPUSET,
CONSTRAINT_MEMORY_POLICY,
+ CONSTRAINT_MEMCG,
};
extern int try_set_zone_oom(struct zonelist *zonelist, gfp_t gfp_flags);
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 01b5e01..fca886d 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -521,17 +521,40 @@
return oom_kill_task(victim);
}
+/*
+ * Determines whether the kernel must panic because of the panic_on_oom sysctl.
+ */
+static void check_panic_on_oom(enum oom_constraint constraint, gfp_t gfp_mask,
+ int order)
+{
+ if (likely(!sysctl_panic_on_oom))
+ return;
+ if (sysctl_panic_on_oom != 2) {
+ /*
+ * panic_on_oom == 1 only affects CONSTRAINT_NONE, the kernel
+ * does not panic for cpuset, mempolicy, or memcg allocation
+ * failures.
+ */
+ if (constraint != CONSTRAINT_NONE)
+ return;
+ }
+ read_lock(&tasklist_lock);
+ dump_header(NULL, gfp_mask, order, NULL);
+ read_unlock(&tasklist_lock);
+ panic("Out of memory: %s panic_on_oom is enabled\n",
+ sysctl_panic_on_oom == 2 ? "compulsory" : "system-wide");
+}
+
#ifdef CONFIG_CGROUP_MEM_RES_CTLR
void mem_cgroup_out_of_memory(struct mem_cgroup *mem, gfp_t gfp_mask)
{
unsigned long points = 0;
struct task_struct *p;
- if (sysctl_panic_on_oom == 2)
- panic("out of memory(memcg). panic_on_oom is selected.\n");
+ check_panic_on_oom(CONSTRAINT_MEMCG, gfp_mask, 0);
read_lock(&tasklist_lock);
retry:
- p = select_bad_process(&points, mem, CONSTRAINT_NONE, NULL);
+ p = select_bad_process(&points, mem, CONSTRAINT_MEMCG, NULL);
if (!p || PTR_ERR(p) == -1UL)
goto out;
@@ -632,8 +655,8 @@
/* Found nothing?!?! Either we hang forever, or we panic. */
if (!p) {
- read_unlock(&tasklist_lock);
dump_header(NULL, gfp_mask, order, NULL);
+ read_unlock(&tasklist_lock);
panic("Out of memory and no killable processes...\n");
}
@@ -655,9 +678,7 @@
/* Got some memory back in the last second. */
return;
- if (sysctl_panic_on_oom)
- panic("out of memory from page fault. panic_on_oom is selected.\n");
-
+ check_panic_on_oom(CONSTRAINT_NONE, 0, 0);
read_lock(&tasklist_lock);
/* unknown gfp_mask and order */
__out_of_memory(0, 0, CONSTRAINT_NONE, NULL);
@@ -704,29 +725,13 @@
return;
}
- if (sysctl_panic_on_oom == 2) {
- dump_header(NULL, gfp_mask, order, NULL);
- panic("out of memory. Compulsory panic_on_oom is selected.\n");
- }
-
/*
* Check if there were limitations on the allocation (only relevant for
* NUMA) that may require different handling.
*/
constraint = constrained_alloc(zonelist, gfp_mask, nodemask);
+ check_panic_on_oom(constraint, gfp_mask, order);
read_lock(&tasklist_lock);
- if (unlikely(sysctl_panic_on_oom)) {
- /*
- * panic_on_oom only affects CONSTRAINT_NONE, the kernel
- * should not panic for cpuset or mempolicy induced memory
- * failures.
- */
- if (constraint == CONSTRAINT_NONE) {
- dump_header(NULL, gfp_mask, order, NULL);
- read_unlock(&tasklist_lock);
- panic("Out of memory: panic_on_oom is enabled\n");
- }
- }
__out_of_memory(gfp_mask, order, constraint, nodemask);
read_unlock(&tasklist_lock);