mm/hugetlb: fix missing call to restore_reserve_on_error()

When huge_add_to_page_cache() fails, the page is freed directly without
calling restore_reserve_on_error() to restore reserve for newly allocated
pages not in page cache.  Fix this by calling restore_reserve_on_error()
when huge_add_to_page_cache fails.

[linmiaohe@huawei.com: remove err == -EEXIST check and retry logic]
Link: https://lkml.kernel.org/r/20220823030209.57434-4-linmiaohe@huawei.com
Link: https://lkml.kernel.org/r/20220816130553.31406-4-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index ff991e5..8d52827 100644 (file)
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -5563,7 +5563,6 @@ static vm_fault_t hugetlb_no_page(struct mm_struct *mm,
        if (idx >= size)
                goto out;
 
-retry:
        new_page = false;
        page = find_lock_page(mapping, idx);
        if (!page) {
@@ -5603,9 +5602,15 @@ retry:
                if (vma->vm_flags & VM_MAYSHARE) {
                        int err = huge_add_to_page_cache(page, mapping, idx);
                        if (err) {
+                               /*
+                                * err can't be -EEXIST which implies someone
+                                * else consumed the reservation since hugetlb
+                                * fault mutex is held when add a hugetlb page
+                                * to the page cache. So it's safe to call
+                                * restore_reserve_on_error() here.
+                                */
+                               restore_reserve_on_error(h, vma, haddr, page);
                                put_page(page);
-                               if (err == -EEXIST)
-                                       goto retry;
                                goto out;
                        }
                        new_pagecache_page = true;