Re: [PATCH for 6.6 & 6.12] LoongArch: Rework KASAN initialization for PTW-enabled systems

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Sun, Feb 15, 2026 at 10:09:53PM +0800, Huacai Chen wrote:
> From: Tiezhu Yang <yangtiezhu@loongson.cn>
> 
> commit 5ec5ac4ca27e4daa234540ac32f9fc5219377d53 upstream.
> 
> "kasan_early_stage = false" indicates that kasan is fully initialized,
> so it should be put at end of kasan_init().
> 
> Otherwise bringing up the primary CPU failed when CONFIG_KASAN is set
> on PTW-enabled systems, here are the call chains:
> 
>     kernel_entry()
>       start_kernel()
>         setup_arch()
>           kasan_init()
>             kasan_early_stage = false
> 
> The reason is PTW-enabled systems have speculative accesses which means
> memory accesses to the shadow memory after kasan_init() may be executed
> by hardware before. However, accessing shadow memory is safe only after
> kasan fully initialized because kasan_init() uses a temporary PGD table
> until we have populated all levels of shadow page tables and writen the
> PGD register. Moving "kasan_early_stage = false" later can defer the
> occasion of kasan_arch_is_ready(), so as to avoid speculative accesses
> on shadow pages.
> 
> After moving "kasan_early_stage = false" to the end, kasan_init() can no
> longer call kasan_mem_to_shadow() for shadow address conversion because
> it will always return kasan_early_shadow_page. On the other hand, we
> should keep the current logic of kasan_mem_to_shadow() for both the early
> and final stage because there may be instrumentation before kasan_init().
> 
> To solve this, we factor out a new mem_to_shadow() function from current
> kasan_mem_to_shadow() for the shadow address conversion in kasan_init().

The subject line AND the commit text here do not match the upstream
commit AND the diff is different and you did not explain what changed or
why :(

So as-is, I can't take this, sorry.

thanks,

greg k-h