linux-kernel - [PATCH 3.16 024/212] hv: allocate synic pages for all present CPUs

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Message-ID: <lsq.1496331795.741105553@decadent.org.uk>
Date:   Thu, 01 Jun 2017 16:43:15 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "K. Y. Srinivasan" <kys@...rosoft.com>,
        "Greg Kroah-Hartman" <gregkh@...uxfoundation.org>,
        "Vitaly Kuznetsov" <vkuznets@...hat.com>
Subject: [PATCH 3.16 024/212] hv: allocate synic pages for all present CPUs

3.16.44-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Vitaly Kuznetsov <vkuznets@...hat.com>

commit 421b8f20d3c381b215f988b42428f56fc3b82405 upstream.

It may happen that not all CPUs are online when we do hv_synic_alloc() and
in case more CPUs come online later we may try accessing these allocated
structures.

Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com>
Signed-off-by: K. Y. Srinivasan <kys@...rosoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/hv/hv.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/hv/hv.c
+++ b/drivers/hv/hv.c
@@ -264,7 +264,7 @@ int hv_synic_alloc(void)
 	size_t size = sizeof(struct tasklet_struct);
 	int cpu;
 
-	for_each_online_cpu(cpu) {
+	for_each_present_cpu(cpu) {
 		hv_context.event_dpc[cpu] = kmalloc(size, GFP_ATOMIC);
 		if (hv_context.event_dpc[cpu] == NULL) {
 			pr_err("Unable to allocate event dpc\n");
@@ -317,7 +317,7 @@ void hv_synic_free(void)
 {
 	int cpu;
 
-	for_each_online_cpu(cpu)
+	for_each_present_cpu(cpu)
 		hv_synic_free_cpu(cpu);
 }