Re: [PATCH] x86/mm: fix objtool failure with KMSAN enabled

[Thomas Gleixner]

On Thu, Jul 02 2026 at 13:15, Peter Zijlstra wrote:
> A quick test with folio_zero_user() seems to suggest the
> ASM_CALL_CONSTRAINT movement (your patch) generates the same code for
> defconfg as does the unmodified code. The change from the thread linked
> above (input constraint on __builtin_frame_address(0)) generates
> different code.
>
> A third option is to force FRAME_POINTER=y for KMSAN builds -- for now,
> until clang is taught to be less insane.

With FRAME_POINTER=y I get now with clang-22

vmlinux.o: warning: objtool: folio_zero_user+0xa7b: stack state mismatch: reg1[4]=-1+0 reg2[4]=-2-336
vmlinux.o: warning: objtool: set_ftrace_ops_ro+0x64: relocation to !ENDBR: machine_kexec_prepare+0x8f0

That's with your objtool patch applied. When I remove that then the
folio_zero_user one goes away. The relocation to !ENDBR stays.

Oh well...