Re: [PATCH v1 1/4] kasan: introduce set_pmd_early_shadow()
From: Sergey Dyasli
Date: Wed Jan 15 2020 - 05:54:52 EST
Hi Juergen,
On 08/01/2020 15:20, Sergey Dyasli wrote:
> It is incorrect to call pmd_populate_kernel() multiple times for the
> same page table. Xen notices it during kasan_populate_early_shadow():
>
> (XEN) mm.c:3222:d155v0 mfn 3704b already pinned
>
> This happens for kasan_early_shadow_pte when USE_SPLIT_PTE_PTLOCKS is
> enabled. Fix this by introducing set_pmd_early_shadow() which calls
> pmd_populate_kernel() only once and uses set_pmd() afterwards.
>
> Signed-off-by: Sergey Dyasli <sergey.dyasli@xxxxxxxxxx>
Looks like the plan to use set_pmd() directly has failed: it's an
arch-specific function and can't be used in arch-independent code
(as kbuild test robot has proven).
Do you see any way out of this other than disabling SPLIT_PTE_PTLOCKS
for PV KASAN?
--
Thanks,
Sergey