diff options
authorMina Almasry <>2021-11-19 16:43:43 -0800
committerLinus Torvalds <>2021-11-20 10:35:54 -0800
commitcc30042df6fcc82ea18acf0dace831503e60a0b7 (patch)
parentafe041c2d0febd83698b8b0164e6b3b1dfae0b66 (diff)
hugetlb, userfaultfd: fix reservation restore on userfaultfd error
Currently in the is_continue case in hugetlb_mcopy_atomic_pte(), if we bail out using "goto out_release_unlock;" in the cases where idx >= size, or !huge_pte_none(), the code will detect that new_pagecache_page == false, and so call restore_reserve_on_error(). In this case I see restore_reserve_on_error() delete the reservation, and the following call to remove_inode_hugepages() will increment h->resv_hugepages causing a 100% reproducible leak. We should treat the is_continue case similar to adding a page into the pagecache and set new_pagecache_page to true, to indicate that there is no reservation to restore on the error path, and we need not call restore_reserve_on_error(). Rename new_pagecache_page to page_in_pagecache to make that clear. Link: Fixes: c7b1850dfb41 ("hugetlb: don't pass page cache pages to restore_reserve_on_error") Signed-off-by: Mina Almasry <> Reported-by: James Houghton <> Reviewed-by: Mike Kravetz <> Cc: Wei Xu <> Cc: <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
1 files changed, 4 insertions, 3 deletions
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 3a2479003ddf..f025d234522f 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -5736,13 +5736,14 @@ int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm,
int ret = -ENOMEM;
struct page *page;
int writable;
- bool new_pagecache_page = false;
+ bool page_in_pagecache = false;
if (is_continue) {
ret = -EFAULT;
page = find_lock_page(mapping, idx);
if (!page)
goto out;
+ page_in_pagecache = true;
} else if (!*pagep) {
/* If a page already exists, then it's UFFDIO_COPY for
* a non-missing case. Return -EEXIST.
@@ -5830,7 +5831,7 @@ int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm,
ret = huge_add_to_page_cache(page, mapping, idx);
if (ret)
goto out_release_nounlock;
- new_pagecache_page = true;
+ page_in_pagecache = true;
ptl = huge_pte_lockptr(h, dst_mm, dst_pte);
@@ -5894,7 +5895,7 @@ out_release_unlock:
if (vm_shared || is_continue)
- if (!new_pagecache_page)
+ if (!page_in_pagecache)
restore_reserve_on_error(h, dst_vma, dst_addr, page);
goto out;