linux-kernel - [PATCH] mm: add more BUILD_BUG_ONs to gfp

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Message-Id: <20220726230241.3770532-1-pcc@google.com>
Date:   Tue, 26 Jul 2022 16:02:41 -0700
From:   Peter Collingbourne <pcc@...gle.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Peter Collingbourne <pcc@...gle.com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] mm: add more BUILD_BUG_ONs to gfp_migratetype()

gfp_migratetype() also expects GFP_RECLAIMABLE and
GFP_MOVABLE|GFP_RECLAIMABLE to be shiftable into MIGRATE_* enum values,
so add some more BUILD_BUG_ONs to reflect this assumption.

Link: https://linux-review.googlesource.com/id/Iae64e2182f75c3aca776a486b71a72571d66d83e
Signed-off-by: Peter Collingbourne <pcc@...gle.com>
---
 include/linux/gfp.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index f314be58fa77..ea6cb9399152 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -18,6 +18,9 @@ static inline int gfp_migratetype(const gfp_t gfp_flags)
 	VM_WARN_ON((gfp_flags & GFP_MOVABLE_MASK) == GFP_MOVABLE_MASK);
 	BUILD_BUG_ON((1UL << GFP_MOVABLE_SHIFT) != ___GFP_MOVABLE);
 	BUILD_BUG_ON((___GFP_MOVABLE >> GFP_MOVABLE_SHIFT) != MIGRATE_MOVABLE);
+	BUILD_BUG_ON((___GFP_RECLAIMABLE >> GFP_MOVABLE_SHIFT) != MIGRATE_RECLAIMABLE);
+	BUILD_BUG_ON(((___GFP_MOVABLE | ___GFP_RECLAIMABLE) >>
+		      GFP_MOVABLE_SHIFT) != MIGRATE_HIGHATOMIC);
 
 	if (unlikely(page_group_by_mobility_disabled))
 		return MIGRATE_UNMOVABLE;
-- 
2.37.1.455.g008518b4e5-goog