Re: [PATCH] mm: move phys_mem_access_prot_allowed to header

[Rosen Penev]

On Tue, May 5, 2026 at 10:48 PM Nathan Chancellor <nathan@xxxxxxxxxx> wrote:
>
> On Tue, May 05, 2026 at 11:22:13AM +0200, Arnd Bergmann wrote:
> > On Tue, May 5, 2026, at 10:54, Rosen Penev wrote:
> > > On Tue, May 5, 2026 at 1:29 AM Arnd Bergmann <arnd@xxxxxxxx> wrote:
> > >>
> > >> Does this happen with both ld.bfd and ld.lld? Which version of clang
> > >> and lld are you using?
> > > clang version 22.1.3
> > > Target: x86_64-pc-linux-gnu
> > > Thread model: posix
> > > InstalledDir: /usr/bin
> > >
> > > lld the same.
> >
> > Ok. I've tried to reproduce this with Nathan's llvm-22.1.3 build
> > from https://mirrors.edge.kernel.org/pub/tools/llvm/, but don't
> > see this problem on mips defconfig. Are you using a particular
> > configuration, or do you see this on every build?
>
> This is just the same old integrated assembler vs. recordmcount bug:
>
>   https://github.com/ClangBuiltLinux/linux/issues/981
>   https://github.com/ClangBuiltLinux/linux/issues/1830
>
> It requires CONFIG_LD_DEAD_CODE_DATA_ELIMINATION=y with ftrace, which
> MIPS allmodconfig enables. PowerPC worked around this in commit
> f8b2336f15f3 ("powerpc: Avoid dead code/data elimination when using
> recordmcount"). Maybe something along the same lines should be done for
> MIPS.
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -82,7 +82,7 @@ config MIPS
        select HAVE_IRQ_TIME_ACCOUNTING
        select HAVE_KPROBES
        select HAVE_KRETPROBES
-       select HAVE_LD_DEAD_CODE_DATA_ELIMINATION
+       select HAVE_LD_DEAD_CODE_DATA_ELIMINATION if HAVE_OBJTOOL_MCOUNT
        select HAVE_MOD_ARCH_SPECIFIC
        select HAVE_NMI
        select HAVE_PAGE_SIZE_4KB if !CPU_LOONGSON2EF && !CPU_LOONGSON64

fixes it. I see master has a different line for powerpc. I defer to
the experts on this.
>
> Cheers,
> Nathan