diff options
| -rw-r--r-- | mm/hugetlb.c | 31 |
1 files changed, 31 insertions, 0 deletions
diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 88e708be1f64..eb7180db3033 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -174,6 +174,17 @@ static int __init hugetlb_setup(char *s) } __setup("hugepages=", hugetlb_setup); +static unsigned int cpuset_mems_nr(unsigned int *array) +{ + int node; + unsigned int nr = 0; + + for_each_node_mask(node, cpuset_current_mems_allowed) + nr += array[node]; + + return nr; +} + #ifdef CONFIG_SYSCTL static void update_and_free_page(struct page *page) { @@ -819,6 +830,26 @@ int hugetlb_reserve_pages(struct inode *inode, long from, long to) chg = region_chg(&inode->i_mapping->private_list, from, to); if (chg < 0) return chg; + /* + * When cpuset is configured, it breaks the strict hugetlb page + * reservation as the accounting is done on a global variable. Such + * reservation is completely rubbish in the presence of cpuset because + * the reservation is not checked against page availability for the + * current cpuset. Application can still potentially OOM'ed by kernel + * with lack of free htlb page in cpuset that the task is in. + * Attempt to enforce strict accounting with cpuset is almost + * impossible (or too ugly) because cpuset is too fluid that + * task or memory node can be dynamically moved between cpusets. + * + * The change of semantics for shared hugetlb mapping with cpuset is + * undesirable. However, in order to preserve some of the semantics, + * we fall back to check against current free page availability as + * a best attempt and hopefully to minimize the impact of changing + * semantics that cpuset has. + */ + if (chg > cpuset_mems_nr(free_huge_pages_node)) + return -ENOMEM; + ret = hugetlb_acct_memory(chg); if (ret < 0) return ret; |