try_set_zonelist_oom() and clear_zonelist_oom() are not named properly to imply
that they require locking semantics to avoid out_of_memory() being reordered.
zone_scan_lock is required for both functions to ensure that there is proper
locking synchronization.
Rename try_set_zonelist_oom() to oom_zonelist_trylock() and rename
clear_zonelist_oom() to oom_zonelist_unlock() to imply there is proper locking
semantics.
At the same time, convert oom_zonelist_trylock() to return bool instead of int
since only success and failure are tested.
Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx>
---
include/linux/oom.h | 4 ++--
mm/oom_kill.c | 30 +++++++++++++-----------------
mm/page_alloc.c | 6 +++---
3 files changed, 18 insertions(+), 22 deletions(-)
diff --git a/include/linux/oom.h b/include/linux/oom.h
--- a/include/linux/oom.h
+++ b/include/linux/oom.h
@@ -55,8 +55,8 @@ extern void oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
struct mem_cgroup *memcg, nodemask_t *nodemask,
const char *message);
-extern int try_set_zonelist_oom(struct zonelist *zonelist, gfp_t gfp_flags);
-extern void clear_zonelist_oom(struct zonelist *zonelist, gfp_t gfp_flags);
+extern bool oom_zonelist_trylock(struct zonelist *zonelist, gfp_t gfp_flags);
+extern void oom_zonelist_unlock(struct zonelist *zonelist, gfp_t gfp_flags);
extern void check_panic_on_oom(enum oom_constraint constraint, gfp_t gfp_mask,
int order, const nodemask_t *nodemask);
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -557,28 +557,25 @@ EXPORT_SYMBOL_GPL(unregister_oom_notifier);
* if a parallel OOM killing is already taking place that includes a zone in
* the zonelist. Otherwise, locks all zones in the zonelist and returns 1.
*/
-int try_set_zonelist_oom(struct zonelist *zonelist, gfp_t gfp_mask)
+bool oom_zonelist_trylock(struct zonelist *zonelist, gfp_t gfp_mask)
{
struct zoneref *z;
struct zone *zone;
- int ret = 1;
+ bool ret = true;
spin_lock(&zone_scan_lock);
- for_each_zone_zonelist(zone, z, zonelist, gfp_zone(gfp_mask)) {
+ for_each_zone_zonelist(zone, z, zonelist, gfp_zone(gfp_mask))
if (zone_is_oom_locked(zone)) {
- ret = 0;
+ ret = false;
goto out;
}
- }
- for_each_zone_zonelist(zone, z, zonelist, gfp_zone(gfp_mask)) {
- /*
- * Lock each zone in the zonelist under zone_scan_lock so a
- * parallel invocation of try_set_zonelist_oom() doesn't succeed
- * when it shouldn't.
- */
+ /*
+ * Lock each zone in the zonelist under zone_scan_lock so a parallel
+ * call to oom_zonelist_trylock() doesn't succeed when it shouldn't.
+ */
+ for_each_zone_zonelist(zone, z, zonelist, gfp_zone(gfp_mask))
zone_set_flag(zone, ZONE_OOM_LOCKED);
- }
out:
spin_unlock(&zone_scan_lock);
@@ -590,15 +587,14 @@ out:
* allocation attempts with zonelists containing them may now recall the OOM
* killer, if necessary.
*/
-void clear_zonelist_oom(struct zonelist *zonelist, gfp_t gfp_mask)
+void oom_zonelist_unlock(struct zonelist *zonelist, gfp_t gfp_mask)
{
struct zoneref *z;
struct zone *zone;
spin_lock(&zone_scan_lock);
- for_each_zone_zonelist(zone, z, zonelist, gfp_zone(gfp_mask)) {
+ for_each_zone_zonelist(zone, z, zonelist, gfp_zone(gfp_mask))
zone_clear_flag(zone, ZONE_OOM_LOCKED);
- }
spin_unlock(&zone_scan_lock);
}
@@ -693,8 +689,8 @@ void pagefault_out_of_memory(void)
return;
zonelist = node_zonelist(first_memory_node, GFP_KERNEL);
- if (try_set_zonelist_oom(zonelist, GFP_KERNEL)) {
+ if (oom_zonelist_trylock(zonelist, GFP_KERNEL)) {
out_of_memory(zonelist, 0, 0, NULL, false);
- clear_zonelist_oom(zonelist, GFP_KERNEL);
+ oom_zonelist_unlock(zonelist, GFP_KERNEL);
}
}
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2201,8 +2201,8 @@ __alloc_pages_may_oom(gfp_t gfp_mask, unsigned int order,
{
struct page *page;
- /* Acquire the OOM killer lock for the zones in zonelist */
- if (!try_set_zonelist_oom(zonelist, gfp_mask)) {
+ /* Acquire the per-zone oom lock for each zone */
+ if (!oom_zonelist_trylock(zonelist, gfp_mask)) {
schedule_timeout_uninterruptible(1);
return NULL;
}
@@ -2240,7 +2240,7 @@ __alloc_pages_may_oom(gfp_t gfp_mask, unsigned int order,
out_of_memory(zonelist, gfp_mask, order, nodemask, false);
out:
- clear_zonelist_oom(zonelist, gfp_mask);
+ oom_zonelist_unlock(zonelist, gfp_mask);
return page;
}
--
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