The patch titled
Subject: mm/hugetlb: initialize order with UINT_MAX in dissolve_free_huge_pages()
has been added to the -mm tree. Its filename is
mm-hugetlb-initialize-order-with-uint_max-in-dissolve_free_huge_pages.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-hugetlb-initialize-order-with-uint_max-in-dissolve_free_huge_pages.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-hugetlb-initialize-order-with-uint_max-in-dissolve_free_huge_pages.patch
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------------------------------------------------------
From: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Subject: mm/hugetlb: initialize order with UINT_MAX in dissolve_free_huge_pages()
Currently the initial value of order in dissolve_free_huge_page is 64 or
32, which leads to the following warning in static checker:
mm/hugetlb.c:1203 dissolve_free_huge_pages()
warn: potential right shift more than type allows '9,18,64'
This is a potential risk of infinite loop, because 1 << order (== 0)
is used in for-loop like this:
for (pfn =3D start_pfn; pfn < end_pfn; pfn +=3D 1 << order)
...
So this patch simply avoids the risk by initializing with UINT_MAX.
Fixes: c8721bbbdd36 ("mm: memory-hotplug: enable memory hotplug to handle hugepage")
Signed-off-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/hugetlb.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff -puN mm/hugetlb.c~mm-hugetlb-initialize-order-with-uint_max-in-dissolve_free_huge_pages mm/hugetlb.c
--- a/mm/hugetlb.c~mm-hugetlb-initialize-order-with-uint_max-in-dissolve_free_huge_pages
+++ a/mm/hugetlb.c
@@ -1188,7 +1188,7 @@ static void dissolve_free_huge_page(stru
*/
void dissolve_free_huge_pages(unsigned long start_pfn, unsigned long end_pfn)
{
- unsigned int order = 8 * sizeof(void *);
+ unsigned int order = UINT_MAX;
unsigned long pfn;
struct hstate *h;
@@ -1200,6 +1200,7 @@ void dissolve_free_huge_pages(unsigned l
if (order > huge_page_order(h))
order = huge_page_order(h);
VM_BUG_ON(!IS_ALIGNED(start_pfn, 1 << order));
+ VM_BUG_ON(order == UINT_MAX);
for (pfn = start_pfn; pfn < end_pfn; pfn += 1 << order)
dissolve_free_huge_page(pfn_to_page(pfn));
}
_
Patches currently in -mm which might be from n-horiguchi@xxxxxxxxxxxxx are
tools-vm-fix-page-flags-build.patch
mm-hwpoison-add-comment-describing-when-to-add-new-cases.patch
mm-hwpoison-remove-obsolete-notebook-todo-list.patch
memory-failure-export-page_type-and-action-result.patch
memory-failure-change-type-of-action_results-param-3-to-enum.patch
tracing-add-trace-event-for-memory-failure.patch
mm-memory-failure-split-thp-earlier-in-memory-error-handling.patch
mm-memory-failure-introduce-get_hwpoison_page-for-consistent-refcount-handling.patch
mm-soft-offline-dont-free-target-page-in-successful-page-migration.patch
mm-memory-failure-me_huge_page-does-nothing-for-thp.patch
mm-hugetlb-initialize-order-with-uint_max-in-dissolve_free_huge_pages.patch
page-flags-trivial-cleanup-for-pagetrans-helpers.patch
page-flags-introduce-page-flags-policies-wrt-compound-pages.patch
page-flags-define-pg_locked-behavior-on-compound-pages.patch
page-flags-define-behavior-of-fs-io-related-flags-on-compound-pages.patch
page-flags-define-behavior-of-lru-related-flags-on-compound-pages.patch
page-flags-define-behavior-slb-related-flags-on-compound-pages.patch
page-flags-define-behavior-of-xen-related-flags-on-compound-pages.patch
page-flags-define-pg_reserved-behavior-on-compound-pages.patch
page-flags-define-pg_swapbacked-behavior-on-compound-pages.patch
page-flags-define-pg_swapcache-behavior-on-compound-pages.patch
page-flags-define-pg_mlocked-behavior-on-compound-pages.patch
page-flags-define-pg_uncached-behavior-on-compound-pages.patch
page-flags-define-pg_uptodate-behavior-on-compound-pages.patch
page-flags-look-on-head-page-if-the-flag-is-encoded-in-page-mapping.patch
mm-sanitize-page-mapping-for-tail-pages.patch
do_shared_fault-check-that-mmap_sem-is-held.patch
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