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mm, oom: rename zonelist locking functions 

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@google.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
David Rientjes 2014-08-06 16:07:52 -07:00 committed by Linus Torvalds
parent 8d060bf490
commit e972a070e2
3 changed files with 18 additions and 22 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
include/linux/oom.h
View File

@ -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);

30
mm/oom_kill.c
View File

@ -559,28 +559,25 @@ 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);
@ -592,15 +589,14 @@ int try_set_zonelist_oom(struct zonelist *zonelist, gfp_t gfp_mask)
* 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);
}
@ -695,8 +691,8 @@ 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(NULL, 0, 0, NULL, false);
clear_zonelist_oom(zonelist, GFP_KERNEL);
oom_zonelist_unlock(zonelist, GFP_KERNEL);
}
}

6
mm/page_alloc.c
View File

@ -2246,8 +2246,8 @@ __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;
}
@ -2285,7 +2285,7 @@ __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;
}