1 files changed, 59 insertions, 70 deletions

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 7a0a73d2fcff..eeceeeb09019 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -35,7 +35,6 @@
 #include <linux/node.h>
 #include "internal.h"
 
-const unsigned long hugetlb_zero = 0, hugetlb_infinity = ~0UL;
 unsigned long hugepages_treat_as_movable;
 
 int hugetlb_max_hstate __read_mostly;
@@ -1089,6 +1088,9 @@ void dissolve_free_huge_pages(unsigned long start_pfn, unsigned long end_pfn)
         unsigned long pfn;
         struct hstate *h;
 
+        if (!hugepages_supported())
+                return;
+
         /* Set scan step to minimum hugepage size */
         for_each_hstate(h)
                 if (order > huge_page_order(h))
@@ -1734,21 +1736,13 @@ static ssize_t nr_hugepages_show_common(struct kobject *kobj,
         return sprintf(buf, "%lu\n", nr_huge_pages);
 }
 
-static ssize_t nr_hugepages_store_common(bool obey_mempolicy,
-                        struct kobject *kobj, struct kobj_attribute *attr,
-                        const char *buf, size_t len)
+static ssize_t __nr_hugepages_store_common(bool obey_mempolicy,
+                                           struct hstate *h, int nid,
+                                           unsigned long count, size_t len)
 {
         int err;
-        int nid;
-        unsigned long count;
-        struct hstate *h;
         NODEMASK_ALLOC(nodemask_t, nodes_allowed, GFP_KERNEL | __GFP_NORETRY);
 
-        err = kstrtoul(buf, 10, &count);
-        if (err)
-                goto out;
-
-        h = kobj_to_hstate(kobj, &nid);
         if (hstate_is_gigantic(h) && !gigantic_page_supported()) {
                 err = -EINVAL;
                 goto out;
@@ -1784,6 +1778,23 @@ out:
         return err;
 }
 
+static ssize_t nr_hugepages_store_common(bool obey_mempolicy,
+                                         struct kobject *kobj, const char *buf,
+                                         size_t len)
+{
+        struct hstate *h;
+        unsigned long count;
+        int nid;
+        int err;
+
+        err = kstrtoul(buf, 10, &count);
+        if (err)
+                return err;
+
+        h = kobj_to_hstate(kobj, &nid);
+        return __nr_hugepages_store_common(obey_mempolicy, h, nid, count, len);
+}
+
 static ssize_t nr_hugepages_show(struct kobject *kobj,
                                        struct kobj_attribute *attr, char *buf)
 {
@@ -1793,7 +1804,7 @@ static ssize_t nr_hugepages_show(struct kobject *kobj,
 static ssize_t nr_hugepages_store(struct kobject *kobj,
                struct kobj_attribute *attr, const char *buf, size_t len)
 {
-        return nr_hugepages_store_common(false, kobj, attr, buf, len);
+        return nr_hugepages_store_common(false, kobj, buf, len);
 }
 HSTATE_ATTR(nr_hugepages);
 
@@ -1812,7 +1823,7 @@ static ssize_t nr_hugepages_mempolicy_show(struct kobject *kobj,
 static ssize_t nr_hugepages_mempolicy_store(struct kobject *kobj,
                struct kobj_attribute *attr, const char *buf, size_t len)
 {
-        return nr_hugepages_store_common(true, kobj, attr, buf, len);
+        return nr_hugepages_store_common(true, kobj, buf, len);
 }
 HSTATE_ATTR(nr_hugepages_mempolicy);
 #endif
@@ -2248,36 +2259,21 @@ static int hugetlb_sysctl_handler_common(bool obey_mempolicy,
                          void __user *buffer, size_t *length, loff_t *ppos)
 {
         struct hstate *h = &default_hstate;
-        unsigned long tmp;
+        unsigned long tmp = h->max_huge_pages;
         int ret;
 
         if (!hugepages_supported())
                 return -ENOTSUPP;
 
-        tmp = h->max_huge_pages;
-
-        if (write && hstate_is_gigantic(h) && !gigantic_page_supported())
-                return -EINVAL;
-
         table->data = &tmp;
         table->maxlen = sizeof(unsigned long);
         ret = proc_doulongvec_minmax(table, write, buffer, length, ppos);
         if (ret)
                 goto out;
 
-        if (write) {
-                NODEMASK_ALLOC(nodemask_t, nodes_allowed,
-                                                GFP_KERNEL | __GFP_NORETRY);
-                if (!(obey_mempolicy &&
-                               init_nodemask_of_mempolicy(nodes_allowed))) {
-                        NODEMASK_FREE(nodes_allowed);
-                        nodes_allowed = &node_states[N_MEMORY];
-                }
-                h->max_huge_pages = set_max_huge_pages(h, tmp, nodes_allowed);
-
-                if (nodes_allowed != &node_states[N_MEMORY])
-                        NODEMASK_FREE(nodes_allowed);
-        }
+        if (write)
+                ret = __nr_hugepages_store_common(obey_mempolicy, h,
+                                                  NUMA_NO_NODE, tmp, *length);
 out:
         return ret;
 }
@@ -2754,8 +2750,8 @@ void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
  * from other VMAs and let the children be SIGKILLed if they are faulting the
  * same region.
  */
-static int unmap_ref_private(struct mm_struct *mm, struct vm_area_struct *vma,
-                                struct page *page, unsigned long address)
+static void unmap_ref_private(struct mm_struct *mm, struct vm_area_struct *vma,
+                              struct page *page, unsigned long address)
 {
         struct hstate *h = hstate_vma(vma);
         struct vm_area_struct *iter_vma;
@@ -2794,8 +2790,6 @@ static int unmap_ref_private(struct mm_struct *mm, struct vm_area_struct *vma,
                                              address + huge_page_size(h), page);
         }
         mutex_unlock(&mapping->i_mmap_mutex);
-
-        return 1;
 }
 
 /*
@@ -2810,7 +2804,7 @@ static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
 {
         struct hstate *h = hstate_vma(vma);
         struct page *old_page, *new_page;
-        int outside_reserve = 0;
+        int ret = 0, outside_reserve = 0;
         unsigned long mmun_start;       /* For mmu_notifiers */
         unsigned long mmun_end;         /* For mmu_notifiers */
 
@@ -2840,14 +2834,14 @@ retry_avoidcopy:
 
         page_cache_get(old_page);
 
-        /* Drop page table lock as buddy allocator may be called */
+        /*
+         * Drop page table lock as buddy allocator may be called. It will
+         * be acquired again before returning to the caller, as expected.
+         */
         spin_unlock(ptl);
         new_page = alloc_huge_page(vma, address, outside_reserve);
 
         if (IS_ERR(new_page)) {
-                long err = PTR_ERR(new_page);
-                page_cache_release(old_page);
-
                 /*
                  * If a process owning a MAP_PRIVATE mapping fails to COW,
                  * it is due to references held by a child and an insufficient
@@ -2856,29 +2850,25 @@ retry_avoidcopy:
                  * may get SIGKILLed if it later faults.
                  */
                 if (outside_reserve) {
+                        page_cache_release(old_page);
                         BUG_ON(huge_pte_none(pte));
-                        if (unmap_ref_private(mm, vma, old_page, address)) {
-                                BUG_ON(huge_pte_none(pte));
-                                spin_lock(ptl);
-                                ptep = huge_pte_offset(mm, address & huge_page_mask(h));
-                                if (likely(ptep &&
-                                           pte_same(huge_ptep_get(ptep), pte)))
-                                        goto retry_avoidcopy;
-                                /*
-                                 * race occurs while re-acquiring page table
-                                 * lock, and our job is done.
-                                 */
-                                return 0;
-                        }
-                        WARN_ON_ONCE(1);
+                        unmap_ref_private(mm, vma, old_page, address);
+                        BUG_ON(huge_pte_none(pte));
+                        spin_lock(ptl);
+                        ptep = huge_pte_offset(mm, address & huge_page_mask(h));
+                        if (likely(ptep &&
+                                   pte_same(huge_ptep_get(ptep), pte)))
+                                goto retry_avoidcopy;
+                        /*
+                         * race occurs while re-acquiring page table
+                         * lock, and our job is done.
+                         */
+                        return 0;
                 }
 
-                /* Caller expects lock to be held */
-                spin_lock(ptl);
-                if (err == -ENOMEM)
-                        return VM_FAULT_OOM;
-                else
-                        return VM_FAULT_SIGBUS;
+                ret = (PTR_ERR(new_page) == -ENOMEM) ?
+                        VM_FAULT_OOM : VM_FAULT_SIGBUS;
+                goto out_release_old;
         }
 
         /*
@@ -2886,11 +2876,8 @@ retry_avoidcopy:
          * anon_vma prepared.
          */
         if (unlikely(anon_vma_prepare(vma))) {
-                page_cache_release(new_page);
-                page_cache_release(old_page);
-                /* Caller expects lock to be held */
-                spin_lock(ptl);
-                return VM_FAULT_OOM;
+                ret = VM_FAULT_OOM;
+                goto out_release_all;
         }
 
         copy_user_huge_page(new_page, old_page, address, vma,
@@ -2900,6 +2887,7 @@ retry_avoidcopy:
         mmun_start = address & huge_page_mask(h);
         mmun_end = mmun_start + huge_page_size(h);
         mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
+
         /*
          * Retake the page table lock to check for racing updates
          * before the page tables are altered
@@ -2920,12 +2908,13 @@ retry_avoidcopy:
         }
         spin_unlock(ptl);
         mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
+out_release_all:
         page_cache_release(new_page);
+out_release_old:
         page_cache_release(old_page);
 
-        /* Caller expects lock to be held */
-        spin_lock(ptl);
-        return 0;
+        spin_lock(ptl); /* Caller expects lock to be held */
+        return ret;
 }
 
 /* Return the pagecache page at a given address within a VMA */