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@xxxxxxxxxxxxxx>
Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx>
---
include/linux/oom.h | 1 +
mm/oom_kill.c | 53 +++++++++++++++++++++++++++-----------------------
2 files changed, 30 insertions(+), 24 deletions(-)
diff --git a/include/linux/oom.h b/include/linux/oom.h
--- a/include/linux/oom.h
+++ b/include/linux/oom.h
@@ -22,6 +22,7 @@ enum oom_constraint {
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
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -505,17 +505,40 @@ static int oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
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;
@@ -616,8 +639,8 @@ retry:
/* 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");
}
@@ -639,9 +662,7 @@ void pagefault_out_of_memory(void)
/* 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);
@@ -688,29 +709,13 @@ void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask,
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);
--
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