minor nit that hugetlb_report_{,node_}meminfo() does not lock the
reading of nr_huge_pages, free_huge_pages, and friends so this is not an
atomic set of information put into the buffer. If /proc/meminfo is read
while the number of hugetlb pages is in flux it is possible to get
incorrect output such as:
HugePages_Total: 7
HugePages_Free: 8
HugePages_Rsvd: 0
Hugepagesize: 4096 kB
(test available at https://bugzilla.redhat.com/attachment.cgi?id=309864)
With the patch we beat on a number of boxes for hours with the above
test and saw no inconsistencies in the meminfo output.
Signed-off-by: Eric Paris <eparis@redhat.com>
---
mm/hugetlb.c | 12 ++++++++++--
1 files changed, 10 insertions(+), 2 deletions(-)
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index ab17127..fe074d1 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -687,7 +687,9 @@ int hugetlb_overcommit_handler(struct ctl_table *table, int write,
int hugetlb_report_meminfo(char *buf)
{
- return sprintf(buf,
+ int ret;
+ spin_lock(&hugetlb_lock);
+ ret = sprintf(buf,
"HugePages_Total: %5lu\n"
"HugePages_Free: %5lu\n"
"HugePages_Rsvd: %5lu\n"
@@ -698,17 +700,23 @@ int hugetlb_report_meminfo(char *buf)
resv_huge_pages,
surplus_huge_pages,
HPAGE_SIZE/1024);
+ spin_unlock(&hugetlb_lock);
+ return ret;
}
int hugetlb_report_node_meminfo(int nid, char *buf)
{
- return sprintf(buf,
+ int ret;
+ spin_lock(&hugetlb_lock);
+ ret = sprintf(buf,
"Node %d HugePages_Total: %5u\n"
"Node %d HugePages_Free: %5u\n"
"Node %d HugePages_Surp: %5u\n",
nid, nr_huge_pages_node[nid],
nid, free_huge_pages_node[nid],
nid, surplus_huge_pages_node[nid]);
+ spin_unlock(&hugetlb_lock);
+ return ret;
}
/* Return the number pages of memory we physically have, in PAGE_SIZE units. */
--
