Cpuset hardwall flag: add a mem_hardwall flag to cpusets
This flag provides the hardwalling properties of mem_exclusive, without
enforcing the exclusivity. Either mem_hardwall or mem_exclusive is sufficient
to prevent GFP_KERNEL allocations from passing outside the cpuset's assigned
nodes.
Signed-off-by: Paul Menage <menage@google.com>
Acked-by: Paul Jackson <pj@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index fe5407c..8da627d 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -127,6 +127,7 @@
typedef enum {
CS_CPU_EXCLUSIVE,
CS_MEM_EXCLUSIVE,
+ CS_MEM_HARDWALL,
CS_MEMORY_MIGRATE,
CS_SCHED_LOAD_BALANCE,
CS_SPREAD_PAGE,
@@ -144,6 +145,11 @@
return test_bit(CS_MEM_EXCLUSIVE, &cs->flags);
}
+static inline int is_mem_hardwall(const struct cpuset *cs)
+{
+ return test_bit(CS_MEM_HARDWALL, &cs->flags);
+}
+
static inline int is_sched_load_balance(const struct cpuset *cs)
{
return test_bit(CS_SCHED_LOAD_BALANCE, &cs->flags);
@@ -1042,12 +1048,9 @@
/*
* update_flag - read a 0 or a 1 in a file and update associated flag
- * bit: the bit to update (CS_CPU_EXCLUSIVE, CS_MEM_EXCLUSIVE,
- * CS_SCHED_LOAD_BALANCE,
- * CS_NOTIFY_ON_RELEASE, CS_MEMORY_MIGRATE,
- * CS_SPREAD_PAGE, CS_SPREAD_SLAB)
- * cs: the cpuset to update
- * buf: the buffer where we read the 0 or 1
+ * bit: the bit to update (see cpuset_flagbits_t)
+ * cs: the cpuset to update
+ * turning_on: whether the flag is being set or cleared
*
* Call with cgroup_mutex held.
*/
@@ -1228,6 +1231,7 @@
FILE_MEMLIST,
FILE_CPU_EXCLUSIVE,
FILE_MEM_EXCLUSIVE,
+ FILE_MEM_HARDWALL,
FILE_SCHED_LOAD_BALANCE,
FILE_SCHED_RELAX_DOMAIN_LEVEL,
FILE_MEMORY_PRESSURE_ENABLED,
@@ -1313,6 +1317,9 @@
case FILE_MEM_EXCLUSIVE:
retval = update_flag(CS_MEM_EXCLUSIVE, cs, val);
break;
+ case FILE_MEM_HARDWALL:
+ retval = update_flag(CS_MEM_HARDWALL, cs, val);
+ break;
case FILE_SCHED_LOAD_BALANCE:
retval = update_flag(CS_SCHED_LOAD_BALANCE, cs, val);
break;
@@ -1423,6 +1430,8 @@
return is_cpu_exclusive(cs);
case FILE_MEM_EXCLUSIVE:
return is_mem_exclusive(cs);
+ case FILE_MEM_HARDWALL:
+ return is_mem_hardwall(cs);
case FILE_SCHED_LOAD_BALANCE:
return is_sched_load_balance(cs);
case FILE_MEMORY_MIGRATE:
@@ -1475,6 +1484,13 @@
},
{
+ .name = "mem_hardwall",
+ .read_u64 = cpuset_read_u64,
+ .write_u64 = cpuset_write_u64,
+ .private = FILE_MEM_HARDWALL,
+ },
+
+ {
.name = "sched_load_balance",
.read_u64 = cpuset_read_u64,
.write_u64 = cpuset_write_u64,
@@ -1963,14 +1979,14 @@
}
/*
- * nearest_exclusive_ancestor() - Returns the nearest mem_exclusive
- * ancestor to the specified cpuset. Call holding callback_mutex.
- * If no ancestor is mem_exclusive (an unusual configuration), then
- * returns the root cpuset.
+ * nearest_hardwall_ancestor() - Returns the nearest mem_exclusive or
+ * mem_hardwall ancestor to the specified cpuset. Call holding
+ * callback_mutex. If no ancestor is mem_exclusive or mem_hardwall
+ * (an unusual configuration), then returns the root cpuset.
*/
-static const struct cpuset *nearest_exclusive_ancestor(const struct cpuset *cs)
+static const struct cpuset *nearest_hardwall_ancestor(const struct cpuset *cs)
{
- while (!is_mem_exclusive(cs) && cs->parent)
+ while (!(is_mem_exclusive(cs) || is_mem_hardwall(cs)) && cs->parent)
cs = cs->parent;
return cs;
}
@@ -1984,7 +2000,7 @@
* __GFP_THISNODE is set, yes, we can always allocate. If zone
* z's node is in our tasks mems_allowed, yes. If it's not a
* __GFP_HARDWALL request and this zone's nodes is in the nearest
- * mem_exclusive cpuset ancestor to this tasks cpuset, yes.
+ * hardwalled cpuset ancestor to this tasks cpuset, yes.
* If the task has been OOM killed and has access to memory reserves
* as specified by the TIF_MEMDIE flag, yes.
* Otherwise, no.
@@ -2007,7 +2023,7 @@
* and do not allow allocations outside the current tasks cpuset
* unless the task has been OOM killed as is marked TIF_MEMDIE.
* GFP_KERNEL allocations are not so marked, so can escape to the
- * nearest enclosing mem_exclusive ancestor cpuset.
+ * nearest enclosing hardwalled ancestor cpuset.
*
* Scanning up parent cpusets requires callback_mutex. The
* __alloc_pages() routine only calls here with __GFP_HARDWALL bit
@@ -2030,7 +2046,7 @@
* in_interrupt - any node ok (current task context irrelevant)
* GFP_ATOMIC - any node ok
* TIF_MEMDIE - any node ok
- * GFP_KERNEL - any node in enclosing mem_exclusive cpuset ok
+ * GFP_KERNEL - any node in enclosing hardwalled cpuset ok
* GFP_USER - only nodes in current tasks mems allowed ok.
*
* Rule:
@@ -2067,7 +2083,7 @@
mutex_lock(&callback_mutex);
task_lock(current);
- cs = nearest_exclusive_ancestor(task_cs(current));
+ cs = nearest_hardwall_ancestor(task_cs(current));
task_unlock(current);
allowed = node_isset(node, cs->mems_allowed);