[PATCH] mm/mremap: fix BUILD_BUG_ON() error in get_extent

From: Arnd Bergmann <arnd@kernel.org>
To: Andrew Morton <akpm@linux-foundation.org>,
	Nathan Chancellor <natechancellor@gmail.com>,
	Nick Desaulniers <ndesaulniers@google.com>,
	"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
	Wei Yang <richard.weiyang@linux.alibaba.com>
Cc: Arnd Bergmann <arnd@arndb.de>, Vlastimil Babka <vbabka@suse.cz>,
	Dmitry Safonov <0x7f454c46@gmail.com>,
	Brian Geffon <bgeffon@google.com>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	clang-built-linux@googlegroups.com
Subject: [PATCH] mm/mremap: fix BUILD_BUG_ON() error in get_extent
Date: Wed, 30 Dec 2020 16:40:40 +0100	[thread overview]
Message-ID: <20201230154104.522605-1-arnd@kernel.org> (raw)

From: Arnd Bergmann <arnd@arndb.de>

clang cannt evaluate this function argument at compile time
when the function is not inlined, which leads to a link
time failure:

ld.lld: error: undefined symbol: __compiletime_assert_414
>>> referenced by mremap.c
>>>               mremap.o:(get_extent) in archive mm/built-in.a

Mark the function as __always_inline to avoid it.

Fixes: 9ad9718bfa41 ("mm/mremap: calculate extent in one place")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 mm/mremap.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/mm/mremap.c b/mm/mremap.c
index c5590afe7165..1cb464a07184 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -336,8 +336,9 @@ enum pgt_entry {
  * valid. Else returns a smaller extent bounded by the end of the source and
  * destination pgt_entry.
  */
-static unsigned long get_extent(enum pgt_entry entry, unsigned long old_addr,
-			unsigned long old_end, unsigned long new_addr)
+static __always_inline unsigned long get_extent(enum pgt_entry entry,
+			unsigned long old_addr, unsigned long old_end,
+			unsigned long new_addr)
 {
 	unsigned long next, extent, mask, size;
 
-- 
2.29.2

