Subject: linux-next: build failure after merge of the final tree

From: Mark Brown <[email-masked]>
Date: Wed, 28 Jan 2026 16:17:39 +0000

Hi all,

After merging the final tree, today's linux-next build (x86_64
allnoconfig) failed like this:

In file included from /tmp/next/build/mm/mm_init.c:29:
/tmp/next/build/include/linux/cma.h:68:13: warning: 'cma_skip_dt_default_reserved_mem' defined but not used [-Wunused-function]
   68 | static bool cma_skip_dt_default_reserved_mem(void)
      |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from /tmp/next/build/mm/show_mem.c:9:
/tmp/next/build/include/linux/cma.h:68:13: warning: 'cma_skip_dt_default_reserved_mem' defined but not used [-Wunused-function]
   68 | static bool cma_skip_dt_default_reserved_mem(void)
      |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Building: powerpc allnoconfig
In file included from /tmp/next/build/mm/mm_init.c:29:
/tmp/next/build/include/linux/cma.h:68:13: warning: 'cma_skip_dt_default_reserved_mem' defined but not used [-Wunused-function]
   68 | static bool cma_skip_dt_default_reserved_mem(void)
      |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from /tmp/next/build/mm/show_mem.c:9:
/tmp/next/build/include/linux/cma.h:68:13: warning: 'cma_skip_dt_default_reserved_mem' defined but not used [-Wunused-function]
   68 | static bool cma_skip_dt_default_reserved_mem(void)
      |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Building: powerpc64 allnoconfig
In file included from /tmp/next/build/mm/mm_init.c:29:
/tmp/next/build/include/linux/cma.h:68:13: warning: 'cma_skip_dt_default_reserved_mem' defined but not used [-Wunused-function]
   68 | static bool cma_skip_dt_default_reserved_mem(void)
      |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from /tmp/next/build/mm/show_mem.c:9:
/tmp/next/build/include/linux/cma.h:68:13: warning: 'cma_skip_dt_default_reserved_mem' defined but not used [-Wunused-function]
   68 | static bool cma_skip_dt_default_reserved_mem(void)
      |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Building: powerpc ppc44x_defconfig
In file included from /tmp/next/build/mm/mm_init.c:29:
/tmp/next/build/include/linux/cma.h:68:13: warning: 'cma_skip_dt_default_reserved_mem' defined but not used [-Wunused-function]
   68 | static bool cma_skip_dt_default_reserved_mem(void)
      |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from /tmp/next/build/mm/show_mem.c:9:
/tmp/next/build/include/linux/cma.h:68:13: warning: 'cma_skip_dt_default_reserved_mem' defined but not used [-Wunused-function]
   68 | static bool cma_skip_dt_default_reserved_mem(void)
      |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from /tmp/next/build/kernel/dma/pool.c:6:
/tmp/next/build/include/linux/cma.h:68:13: warning: 'cma_skip_dt_default_reserved_mem' defined but not used [-Wunused-function]
   68 | static bool cma_skip_dt_default_reserved_mem(void)
      |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/tmp/next/build/arch/powerpc/boot/dts/sam440ep.dts:266.22-287.5: Warning (interrupt_provider): /plb/pci@ec000000: '#interrupt-cells' found, but node is not an interrupt provider
Building: powerpc pseries_le_defconfig
In file included from /tmp/next/build/arch/powerpc/kvm/book3s_hv_builtin.c:15:
/tmp/next/build/include/linux/cma.h:68:13: error: 'cma_skip_dt_default_reserved_mem' defined but not used [-Werror=unused-function]
   68 | static bool cma_skip_dt_default_reserved_mem(void)
      |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors
make[5]: *** [/tmp/next/build/scripts/Makefile.build:287: arch/powerpc/kvm/book3s_hv_builtin.o] Error 1
make[5]: *** Waiting for unfinished jobs....
make[4]: *** [/tmp/next/build/scripts/Makefile.build:544: arch/powerpc/kvm] Error 2
make[4]: *** Waiting for unfinished jobs....
In file included from /tmp/next/build/mm/mm_init.c:29:
/tmp/next/build/include/linux/cma.h:68:13: warning: 'cma_skip_dt_default_reserved_mem' defined but not used [-Wunused-function]
   68 | static bool cma_skip_dt_default_reserved_mem(void)
      |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from /tmp/next/build/mm/show_mem.c:9:
/tmp/next/build/include/linux/cma.h:68:13: warning: 'cma_skip_dt_default_reserved_mem' defined but not used [-Wunused-function]
   68 | static bool cma_skip_dt_default_reserved_mem(void)
      |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from /tmp/next/build/arch/powerpc/kernel/fadump.c:25:
/tmp/next/build/include/linux/cma.h:68:13: error: 'cma_skip_dt_default_reserved_mem' defined but not used [-Werror=unused-function]
   68 | static bool cma_skip_dt_default_reserved_mem(void)
      |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors
make[5]: *** [/tmp/next/build/scripts/Makefile.build:287: arch/powerpc/kernel/fadump.o] Error 1
make[5]: *** Waiting for unfinished jobs....
make[4]: *** [/tmp/next/build/scripts/Makefile.build:544: arch/powerpc/kernel] Error 2
make[3]: *** [/tmp/next/build/scripts/Makefile.build:544: arch/powerpc] Error 2
make[3]: *** Waiting for unfinished jobs....
In file included from /tmp/next/build/mm/hugetlb.c:33:
/tmp/next/build/include/linux/cma.h:68:13: warning: 'cma_skip_dt_default_reserved_mem' defined but not used [-Wunused-function]
   68 | static bool cma_skip_dt_default_reserved_mem(void)
      |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from /tmp/next/build/mm/hugetlb_cma.c:4:
/tmp/next/build/include/linux/cma.h:68:13: warning: 'cma_skip_dt_default_reserved_mem' defined but not used [-Wunused-function]
   68 | static bool cma_skip_dt_default_reserved_mem(void)
      |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from /tmp/next/build/fs/proc/meminfo.c:18:
/tmp/next/build/include/linux/cma.h:68:13: warning: 'cma_skip_dt_default_reserved_mem' defined but not used [-Wunused-function]
   68 | static bool cma_skip_dt_default_reserved_mem(void)
      |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from /tmp/next/build/mm/cma.c:28:
/tmp/next/build/include/linux/cma.h:68:13: warning: 'cma_skip_dt_default_reserved_mem' defined but not used [-Wunused-function]
   68 | static bool cma_skip_dt_default_reserved_mem(void)
      |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from /tmp/next/build/kernel/crash_reserve.c:17:
/tmp/next/build/include/linux/cma.h:68:13: warning: 'cma_skip_dt_default_reserved_mem' defined but not used [-Wunused-function]
   68 | static bool cma_skip_dt_default_reserved_mem(void)

Caused by commit

  26332ae848f08 (of: reserved_mem: Allow reserved_mem framework detect "cma=" kernel param)

I have applied the patch below, which I will post as a submission.

From 51ca24819b2b7ab6ecb632f14cb5975563fe933f Mon Sep 17 00:00:00 2001
From: Mark Brown <[email-masked]>
Date: Wed, 28 Jan 2026 15:22:21 +0000
Subject: [PATCH] cma: Fix stub for cma_skip_dt_default_reserved_mem()

The stub for cma_skip_dt_default_reserved_mem() is not inlined so
triggers build warnings:

In file included from /tmp/next/build/fs/proc/meminfo.c:18:
/tmp/next/build/include/linux/cma.h:68:13: warning: 'cma_skip_dt_default_reserved_mem' defined but not used [-Wunused-function]
   68 | static bool cma_skip_dt_default_reserved_mem(void)
      |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

which are fatal with -Werror.

Fixes: 26332ae848f08 ("of: reserved_mem: Allow reserved_mem framework detect "cma=" kernel param")
Signed-off-by: Mark Brown <[email-masked]>
---
 include/linux/cma.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/cma.h b/include/linux/cma.h
index 0bf408360641b..d0793eaaadaa4 100644
--- a/include/linux/cma.h
+++ b/include/linux/cma.h
@@ -65,7 +65,7 @@ extern void cma_reserve_pages_on_error(struct cma *cma);
 #ifdef CONFIG_DMA_CMA
 extern bool cma_skip_dt_default_reserved_mem(void);
 #else
-static bool cma_skip_dt_default_reserved_mem(void)
+static inline bool cma_skip_dt_default_reserved_mem(void)
 {
 	return false;
 }
-- 
2.47.3