[Devel] [PATCH RHEL7 COMMIT] sched: Fallback to 0-order allocations in sched_create_group()

[Konstantin Khorenko]

The commit is pushed to "branch-rh7-3.10.0-693.11.1.vz7.39.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-693.11.1.vz7.39.10
------>
commit 1200756076730c63d4f4a6ba2e1fbf33fc37c156
Author: Andrey Ryabinin <aryabinin at virtuozzo.com>
Date:   Thu Jan 11 17:39:35 2018 +0300

    sched: Fallback to 0-order allocations in sched_create_group()
    
    On large machines ->cpustat_last/->vcpustat arrays are large
    causing possibly failing high-order allocation:
    
           fio: page allocation failure: order:4, mode:0xc0d0
    
           Call Trace:
             dump_stack+0x19/0x1b
             warn_alloc_failed+0x110/0x180
              __alloc_pages_nodemask+0x7bf/0xc60
             alloc_pages_current+0x98/0x110
             kmalloc_order+0x18/0x40
             kmalloc_order_trace+0x26/0xa0
             __kmalloc+0x279/0x290
             sched_create_group+0xba/0x150
             sched_autogroup_create_attach+0x3f/0x1a0
             sys_setsid+0x73/0xc0
             system_call_fastpath+0x16/0x1b
    
    Use kvzalloc to fallback to vmalloc() and avoid failure if
    high order page is not available.
    
    https://jira.sw.ru/browse/PSBM-79891
    Fixes: 85fd6b2ff490 ("sched: Port cpustat related patches")
    
    Signed-off-by: Andrey Ryabinin <aryabinin at virtuozzo.com>
    Acked-by: Kirill Tkhai <ktkhai at virtuozzo.com>
---
 kernel/sched/core.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 75ef029b1595..6979f7d8ead7 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -8761,8 +8761,8 @@ static void free_sched_group(struct task_group *tg)
 	free_rt_sched_group(tg);
 	autogroup_free(tg);
 	free_percpu(tg->taskstats);
-	kfree(tg->cpustat_last);
-	kfree(tg->vcpustat);
+	kvfree(tg->cpustat_last);
+	kvfree(tg->vcpustat);
 	kfree(tg);
 }
 
@@ -8785,12 +8785,12 @@ struct task_group *sched_create_group(struct task_group *parent)
 	if (!tg->taskstats)
 		goto err;
 
-	tg->cpustat_last = kcalloc(nr_cpu_ids, sizeof(struct kernel_cpustat),
+	tg->cpustat_last = kvzalloc(nr_cpu_ids * sizeof(struct kernel_cpustat),
 				   GFP_KERNEL);
 	if (!tg->cpustat_last)
 		goto err;
 
-	tg->vcpustat = kcalloc(nr_cpu_ids, sizeof(struct kernel_cpustat),
+	tg->vcpustat = kvzalloc(nr_cpu_ids * sizeof(struct kernel_cpustat),
 			       GFP_KERNEL);
 	if (!tg->vcpustat)
 		goto err;