From: Paul Jackson <[email protected]>
Properly check return value of kmalloc'd dynamic sched domain
cpumasks, and fallback to a non-kmalloc'd default (one large
sched domain) if kmalloc fails.
Signed-off-by: Paul Jackson <[email protected]>
---
This fix applies to and goes anywhere after the patch:
cpuset-sched_load_balance-flag.patch
kernel/cpuset.c | 4 +++-
kernel/sched.c | 25 ++++++++++++++++++++++---
2 files changed, 25 insertions(+), 4 deletions(-)
--- 2.6.23-mm1.orig/kernel/cpuset.c 2007-10-16 19:00:34.009537656 -0700
+++ 2.6.23-mm1/kernel/cpuset.c 2007-10-16 23:21:08.036687381 -0700
@@ -587,6 +587,8 @@ static void rebuild_sched_domains(void)
if (is_sched_load_balance(&top_cpuset)) {
ndoms = 1;
doms = kmalloc(sizeof(cpumask_t), GFP_KERNEL);
+ if (!doms)
+ goto rebuild;
*doms = top_cpuset.cpus_allowed;
goto rebuild;
}
@@ -640,7 +642,7 @@ restart:
/* Convert <csn, csa> to <ndoms, doms> */
doms = kmalloc(ndoms * sizeof(cpumask_t), GFP_KERNEL);
if (!doms)
- goto done;
+ goto rebuild;
for (nslot = 0, i = 0; i < csn; i++) {
struct cpuset *a = csa[i];
--- 2.6.23-mm1.orig/kernel/sched.c 2007-10-16 18:55:35.325048140 -0700
+++ 2.6.23-mm1/kernel/sched.c 2007-10-16 23:28:30.635328289 -0700
@@ -6209,6 +6209,13 @@ static cpumask_t *doms_cur; /* current s
static int ndoms_cur; /* number of sched domains in 'doms_cur' */
/*
+ * Special case: If a kmalloc of a doms_cur partition (array of
+ * cpumask_t) fails, then fallback to a single sched domain,
+ * as determined by the single cpumask_t fallback_doms.
+ */
+static cpumask_t fallback_doms;
+
+/*
* Set up scheduler domains and groups. Callers must hold the hotplug lock.
* For now this just excludes isolated cpus, but could be used to
* exclude other special cases in the future.
@@ -6217,6 +6224,8 @@ static int arch_init_sched_domains(const
{
ndoms_cur = 1;
doms_cur = kmalloc(sizeof(cpumask_t), GFP_KERNEL);
+ if (!doms_cur)
+ doms_cur = &fallback_doms;
cpus_andnot(*doms_cur, *cpu_map, cpu_isolated_map);
return build_sched_domains(doms_cur);
@@ -6254,8 +6263,11 @@ static void detach_destroy_domains(const
* current 'doms_cur' domains and in the new 'doms_new', we can leave
* it as it is.
*
- * The passed in 'doms_new' must be kmalloc'd, and this routine takes
- * ownership of it and will kfree it when done with it.
+ * The passed in 'doms_new' should be kmalloc'd. This routine takes
+ * ownership of it and will kfree it when done with it. If the caller
+ * failed the kmalloc call, then it can pass in doms_new == NULL,
+ * and partition_sched_domains() will fallback to the single partition
+ * 'fallback_doms'.
*
* Call with hotplug lock held
*/
@@ -6263,6 +6275,12 @@ void partition_sched_domains(int ndoms_n
{
int i, j;
+ if (doms_new == NULL) {
+ ndoms_new = 1;
+ doms_new = &fallback_doms;
+ cpus_andnot(doms_new[0], cpu_online_map, cpu_isolated_map);
+ }
+
/* Destroy deleted domains */
for (i = 0; i < ndoms_cur; i++) {
for (j = 0; j < ndoms_new; j++) {
@@ -6288,7 +6306,8 @@ match2:
}
/* Remember the new sched domains */
- kfree(doms_cur);
+ if (doms_cur != &fallback_doms)
+ kfree(doms_cur);
doms_cur = doms_new;
ndoms_cur = ndoms_new;
}
--
I won't rest till it's the best ...
Programmer, Linux Scalability
Paul Jackson <[email protected]> 1.650.933.1373
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