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
e0c1326779cc ("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: 9bda131c6093 ("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>

diff --git a/mm/cma.c b/mm/cma.c
index 94b5da468a7d719e5144d33b06bcc7619c0fbcc9..15cc0ae76c8eb8829da71d2948133fdebf708b59 100644 (file)
--- a/mm/cma.c
+++ b/mm/cma.c
@@ -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);