[PATCH v2] mm/slub: clamp slab_min_order to MAX_PAGE_ORDER

[Sang-Heon Jeon <ekffu200098@gmail.com>]

setup_slub_max_order() clamps slab_max_order to MAX_PAGE_ORDER, but
setup_slub_min_order() has no such clamp.

The buddy allocator cannot allocate more than 2^MAX_PAGE_ORDER pages
at once, so slab_min_order above it makes no sense.

If slab_min_order is set above MAX_PAGE_ORDER, it can even panic at
boot or invoke undefined behavior in order_objects().

So clamp slab_min_order to MAX_PAGE_ORDER as well.

Fixes: 81819f0fc828 ("SLUB core")
Signed-off-by: Sang-Heon Jeon <ekffu200098@gmail.com>
---
Changes from v1 [1]
- Change fixes tag to 81819f0fc828 ("SLUB core")
- Remove stable tag

[1] https://lore.kernel.org/all/20261007163403.1643768-1-ekffu200098@gmail.com/#t
---
 mm/slub.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/mm/slub.c b/mm/slub.c
index 1559cbace469..8400df7c222e 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -8354,6 +8354,8 @@ static int __init setup_slub_min_order(const char *str, const struct kernel_para
 	if (ret)
 		return ret;
 
+	slub_min_order = min_t(unsigned int, slub_min_order, MAX_PAGE_ORDER);
+
 	if (slub_min_order > slub_max_order)
 		slub_max_order = slub_min_order;
 

base-commit: d755441b7672c74f29d1241ffdd2b067ecab1ca0
-- 
2.43.0