Commit f4355d6b authored Feb 24, 2026 by Zi Yan Committed by Andrew Morton Mar 04, 2026

mm/cma: move put_page_testzero() out of VM_WARN_ON in cma_release()

When CONFIG_DEBUG_VM is not set, VM_WARN_ON is a NOP.  Putting any
statement with side effect inside it is incorrect.  Collect all
!put_page_testzero() results and check the sum using WARN instead after
the loop.  It restores the same check in free_contig_range() before commit
e0c13267 ("mm: page_alloc: add alloc_contig_frozen_{range,pages}()"),
the commit prior to the Fixes one.

Link: https://lkml.kernel.org/r/20260225031231.2352011-1-ziy@nvidia.com


Fixes: 9bda131c ("mm: cma: add cma_alloc_frozen{_compound}()")
Signed-off-by: Zi Yan <ziy@nvidia.com>
Reported-by: Ron Economos <re@w6rz.net>
Closes: https://lore.kernel.org/all/1b17c38f-30d3-4bb4-a7e1-e74b19ada885@w6rz.net/


Suggested-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Reviewed-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Debugged-by: David Hildenbrand (Arm) <david@kernel.org>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Tested-by: Ron Economos <re@w6rz.net>
Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

parent d210fdca

mm/cma.c

+4 −1

Original line number	Diff line number	Diff line
		@@ -1013,6 +1013,7 @@ bool cma_release(struct cma cma, const struct page pages,
		unsigned long count)
		{
		struct cma_memrange *cmr;
		unsigned long ret = 0;
		unsigned long i, pfn;

		cmr = find_cma_memrange(cma, pages, count);
		@@ -1021,7 +1022,9 @@ bool cma_release(struct cma cma, const struct page pages,

		pfn = page_to_pfn(pages);
		for (i = 0; i < count; i++, pfn++)
		VM_WARN_ON(!put_page_testzero(pfn_to_page(pfn)));
		ret += !put_page_testzero(pfn_to_page(pfn));

		WARN(ret, "%lu pages are still in use!\n", ret);

		__cma_release_frozen(cma, cmr, pages, count);