mm: page_alloc: add __split_page()

Factor out the splitting of non-compound page from make_alloc_exact() and
split_page() into a new helper function __split_page().

While at it, convert the VM_BUG_ON_PAGE() into a VM_WARN_ON_PAGE().

Link: https://lkml.kernel.org/r/20260109093136.1491549-3-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Muchun Song <muchun.song@linux.dev>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Jane Chu <jane.chu@oracle.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
Cc: Mark Brown <broonie@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/include/linux/mmdebug.h b/include/linux/mmdebug.h
index 14a45979cccc9a13d674709c5480b7e8c2977812..ab60ffba08f5fb3544df9b5519f084d23c2db7f1 100644 (file)
--- a/include/linux/mmdebug.h
+++ b/include/linux/mmdebug.h
@@ -47,6 +47,15 @@ void vma_iter_dump_tree(const struct vma_iterator *vmi);
                        BUG();                                          \
                }                                                       \
        } while (0)
+#define VM_WARN_ON_PAGE(cond, page)            ({                      \
+       int __ret_warn = !!(cond);                                      \
+                                                                       \
+       if (unlikely(__ret_warn)) {                                     \
+               dump_page(page, "VM_WARN_ON_PAGE(" __stringify(cond)")");\
+               WARN_ON(1);                                             \
+       }                                                               \
+       unlikely(__ret_warn);                                           \
+})
 #define VM_WARN_ON_ONCE_PAGE(cond, page)       ({                      \
        static bool __section(".data..once") __warned;                  \
        int __ret_warn_once = !!(cond);                                 \
@@ -122,6 +131,7 @@ void vma_iter_dump_tree(const struct vma_iterator *vmi);
 #define VM_BUG_ON_MM(cond, mm) VM_BUG_ON(cond)
 #define VM_WARN_ON(cond) BUILD_BUG_ON_INVALID(cond)
 #define VM_WARN_ON_ONCE(cond) BUILD_BUG_ON_INVALID(cond)
+#define VM_WARN_ON_PAGE(cond, page)  BUILD_BUG_ON_INVALID(cond)
 #define VM_WARN_ON_ONCE_PAGE(cond, page)  BUILD_BUG_ON_INVALID(cond)
 #define VM_WARN_ON_FOLIO(cond, folio)  BUILD_BUG_ON_INVALID(cond)
 #define VM_WARN_ON_ONCE_FOLIO(cond, folio)  BUILD_BUG_ON_INVALID(cond)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index c0b0485847692723d1e60e86e2e9ad52609d04a4..3b99296eda5bccc2fb5b81ee26cf58ecea89bffd 100644 (file)
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3107,6 +3107,15 @@ void free_unref_folios(struct folio_batch *folios)
        folio_batch_reinit(folios);
 }
 
+static void __split_page(struct page *page, unsigned int order)
+{
+       VM_WARN_ON_PAGE(PageCompound(page), page);
+
+       split_page_owner(page, order, 0);
+       pgalloc_tag_split(page_folio(page), order, 0);
+       split_page_memcg(page, order);
+}
+
 /*
  * split_page takes a non-compound higher-order page, and splits it into
  * n (1<<order) sub-pages: page[0..n]
@@ -3119,14 +3128,12 @@ void split_page(struct page *page, unsigned int order)
 {
        int i;
 
-       VM_BUG_ON_PAGE(PageCompound(page), page);
-       VM_BUG_ON_PAGE(!page_count(page), page);
+       VM_WARN_ON_PAGE(!page_count(page), page);
 
        for (i = 1; i < (1 << order); i++)
                set_page_refcounted(page + i);
-       split_page_owner(page, order, 0);
-       pgalloc_tag_split(page_folio(page), order, 0);
-       split_page_memcg(page, order);
+
+       __split_page(page, order);
 }
 EXPORT_SYMBOL_GPL(split_page);
 
@@ -5389,9 +5396,7 @@ static void *make_alloc_exact(unsigned long addr, unsigned int order,
                struct page *page = virt_to_page((void *)addr);
                struct page *last = page + nr;
 
-               split_page_owner(page, order, 0);
-               pgalloc_tag_split(page_folio(page), order, 0);
-               split_page_memcg(page, order);
+               __split_page(page, order);
                while (page < --last)
                        set_page_refcounted(last);