Re: [PATCH] powerpc/32s: Fix boot failure with KASAN + SMP + JUMP_LABEL_FEATURE_CHECK_DEBUG

[Michael Ellerman]

On Fri, 1 Jul 2022 08:06:15 +0200, Christophe Leroy wrote:
> Since commit 4291d085b0b0 ("powerpc/32s: Make pte_update() non
> atomic on 603 core"), pte_update() has been using
> mmu_has_feature(MMU_FTR_HPTE_TABLE) to avoid a useless atomic
> operation on 603 cores.
> 
> When kasan_early_init() sets up the early zero shadow, it uses
> __set_pte_at(). On book3s/32, __set_pte_at() calls pte_update()
> when CONFIG_SMP is selected in order to ensure the preservation of
> _PAGE_HASHPTE in case of concurrent update of the PTE. But that's
> too early for mmu_has_feature(), so when
> CONFIG_JUMP_LABEL_FEATURE_CHECK_DEBUG is selected, mmu_has_feature()
> calls printk(). That's too early to call printk() because KASAN
> early zero shadow page is not set up yet. It leads to a deadlock.
> 
> [...]

Applied to powerpc/next.

[1/1] powerpc/32s: Fix boot failure with KASAN + SMP + JUMP_LABEL_FEATURE_CHECK_DEBUG
      https://git.kernel.org/powerpc/c/6042a1652d643d1d34fa89bb314cb102960c0800

cheers