mm/hugetlb: add mempolicy check in the reservation routine

In the reservation routine, we only check whether the cpuset meets the
memory allocation requirements.  But we ignore the mempolicy of MPOL_BIND
case.  If someone mmap hugetlb succeeds, but the subsequent memory
allocation may fail due to mempolicy restrictions and receives the SIGBUS
signal.  This can be reproduced by the follow steps.

 1) Compile the test case.
    cd tools/testing/selftests/vm/
    gcc map_hugetlb.c -o map_hugetlb

 2) Pre-allocate huge pages. Suppose there are 2 numa nodes in the
    system. Each node will pre-allocate one huge page.
    echo 2 > /proc/sys/vm/nr_hugepages

 3) Run test case(mmap 4MB). We receive the SIGBUS signal.
    numactl --membind=3D0 ./map_hugetlb 4

With this patch applied, the mmap will fail in the step 3) and throw
"mmap: Cannot allocate memory".

[akpm@linux-foundation.org: include sched.h for `current']

Reported-by: Jianchao Guo <guojianchao@bytedance.com>
Suggested-by: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michel Lespinasse <walken@google.com>
Cc: Baoquan He <bhe@redhat.com>
Link: http://lkml.kernel.org/r/20200728034938.14993-1-songmuchun@bytedance.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 15 insertions, 1 deletions

diff --git a/include/linux/mempolicy.h b/include/linux/mempolicy.h
index ea9c15b60a96..5f1648c23e29 100644
--- a/include/linux/mempolicy.h
+++ b/include/linux/mempolicy.h
@@ -6,7 +6,7 @@
 #ifndef _LINUX_MEMPOLICY_H
 #define _LINUX_MEMPOLICY_H 1
 
-
+#include <linux/sched.h>
 #include <linux/mmzone.h>
 #include <linux/dax.h>
 #include <linux/slab.h>
@@ -152,6 +152,15 @@ extern int huge_node(struct vm_area_struct *vma,
 extern bool init_nodemask_of_mempolicy(nodemask_t *mask);
 extern bool mempolicy_nodemask_intersects(struct task_struct *tsk,
 				const nodemask_t *mask);
+extern nodemask_t *policy_nodemask(gfp_t gfp, struct mempolicy *policy);
+
+static inline nodemask_t *policy_nodemask_current(gfp_t gfp)
+{
+	struct mempolicy *mpol = get_task_policy(current);
+
+	return policy_nodemask(gfp, mpol);
+}
+
 extern unsigned int mempolicy_slab_node(void);
 
 extern enum zone_type policy_zone;
@@ -281,5 +290,10 @@ static inline int mpol_misplaced(struct page *page, struct vm_area_struct *vma,
 static inline void mpol_put_task_policy(struct task_struct *task)
 {
 }
+
+static inline nodemask_t *policy_nodemask_current(gfp_t gfp)
+{
+	return NULL;
+}
 #endif /* CONFIG_NUMA */
 #endif