Subject: linux-next: build failure after merge of the mm-nonmm-unstable tree

From: Thierry Reding <[email-masked]>
Date: Wed, 29 Apr 2026 11:10:18 +0200

Hi all,

After merging the mm-nonmm-unstable tree, today's linux-next build
(arm64 defconfig) failed like this:

    In file included from /srv/kbuild/next/linux.git/arch/arm64/include/asm/fixmap.h:118,
                     from /srv/kbuild/next/linux.git/arch/arm64/include/asm/pgtable.h:36,
                     from /srv/kbuild/next/linux.git/include/linux/pgtable.h:6,
                     from /srv/kbuild/next/linux.git/arch/arm64/include/asm/io.h:12,
                     from /srv/kbuild/next/linux.git/include/linux/io.h:12,
                     from /srv/kbuild/next/linux.git/include/acpi/acpi_io.h:5,
                     from /srv/kbuild/next/linux.git/include/linux/acpi.h:40,
                     from /srv/kbuild/next/linux.git/include/acpi/apei.h:9,
                     from /srv/kbuild/next/linux.git/include/acpi/ghes.h:5,
                     from /srv/kbuild/next/linux.git/include/linux/arm_sdei.h:8,
                     from /srv/kbuild/next/linux.git/arch/arm64/kernel/asm-offsets.c:11:
    /srv/kbuild/next/linux.git/include/asm-generic/fixmap.h: In function 'set_fixmap_nocache':
    /srv/kbuild/next/linux.git/include/asm-generic/fixmap.h:54:29: error: 'PAGE_KERNEL_NOCACHE' undeclared (first use in this function); did you mean 'PAGE_KERNEL_ROX'?
       54 | #define FIXMAP_PAGE_NOCACHE PAGE_KERNEL_NOCACHE
          |                             ^~~~~~~~~~~~~~~~~~~
    /srv/kbuild/next/linux.git/include/asm-generic/fixmap.h:93:33: note: in expansion of macro 'FIXMAP_PAGE_NOCACHE'
       93 |         __set_fixmap(idx, phys, FIXMAP_PAGE_NOCACHE);
          |                                 ^~~~~~~~~~~~~~~~~~~
    /srv/kbuild/next/linux.git/include/asm-generic/fixmap.h:54:29: note: each undeclared identifier is reported only once for each function it appears in
       54 | #define FIXMAP_PAGE_NOCACHE PAGE_KERNEL_NOCACHE
          |                             ^~~~~~~~~~~~~~~~~~~
    /srv/kbuild/next/linux.git/include/asm-generic/fixmap.h:93:33: note: in expansion of macro 'FIXMAP_PAGE_NOCACHE'
       93 |         __set_fixmap(idx, phys, FIXMAP_PAGE_NOCACHE);
          |                                 ^~~~~~~~~~~~~~~~~~~
    /srv/kbuild/next/linux.git/include/asm-generic/fixmap.h: In function 'set_fixmap_offset_nocache':
    /srv/kbuild/next/linux.git/include/asm-generic/fixmap.h:54:29: error: 'PAGE_KERNEL_NOCACHE' undeclared (first use in this function); did you mean 'PAGE_KERNEL_ROX'?
       54 | #define FIXMAP_PAGE_NOCACHE PAGE_KERNEL_NOCACHE
          |                             ^~~~~~~~~~~~~~~~~~~
    /srv/kbuild/next/linux.git/include/asm-generic/fixmap.h:99:40: note: in expansion of macro 'FIXMAP_PAGE_NOCACHE'
       99 |         __set_fixmap_offset(idx, phys, FIXMAP_PAGE_NOCACHE);
          |                                        ^~~~~~~~~~~~~~~~~~~

Caused by commit

    dd4bbc6d8e3a ("include/asm-generic/fixmap.h: reimplement nasty macros in C")

I've reverted this patch in linux-next for now.

Thanks,
Thierry