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Date: Wed, 17 Jun 2026 09:48:31 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: Dmitry Voytik <voytikd@gmail.com>
Cc: glider@google.com, jpoimboe@kernel.org, kasan-dev@googlegroups.com,
	linux-kernel@vger.kernel.org
Subject: Re: [BUG] CONFIG_KMSAN breaks objtool and building of the kernel
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On Wed, Jun 17, 2026 at 12:14:26AM +0200, Dmitry Voytik wrote:
> Enabling CONFIG_KMSAN=y triggers the following build error:
> make LLVM=1 -j(nproc)
>   SYNC    include/config/auto.conf
>   DESCEND objtool
>   INSTALL libsubcmd_headers
>   LD      vmlinux.o
> vmlinux.o: warning: objtool: intel_pt_interrupt+0xde9: undefined stack state
> vmlinux.o: warning: objtool: folio_zero_user+0x7cc: undefined stack state
> vmlinux.o: error: objtool: intel_pt_interrupt+0xde4: unknown cfa base reg -1
> make[2]: *** [scripts/Makefile.vmlinux_o:76: vmlinux.o] Error 255
> make[2]: *** Deleting file 'vmlinux.o'
> 
> ↪ git log --oneline | head -n1
> 062871f1371b (HEAD -> master, origin/master, origin/HEAD) Merge tag
> 'pinctrl-v7.1-3' of
> git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrl
> 
> ↪ clang --version
> clang version 22.1.6
> Target: x86_64-pc-linux-gnu
> 
> Please let me know if you need my .config (basically, it's the default
> Arch Linux config + make oldconfg)

Using v7.1-2765-g6b5a2b7d9bc1, clang-22.1.0 (debian) and defconfig+KMSAN, I
cannot reproduce :/