From: Marco Elver <elver@google.com>
To: Dave Hansen <dave.hansen@intel.com>
Cc: Naresh Kamboju <naresh.kamboju@linaro.org>,
Peter Zijlstra <peterz@infradead.org>,
kasan-dev <kasan-dev@googlegroups.com>, X86 ML <x86@kernel.org>,
open list <linux-kernel@vger.kernel.org>,
linux-mm <linux-mm@kvack.org>,
regressions@lists.linux.dev, lkft-triage@lists.linaro.org,
Andrew Morton <akpm@linux-foundation.org>,
Alexander Potapenko <glider@google.com>
Subject: Re: WARNING: CPU: 0 PID: 0 at arch/x86/include/asm/kfence.h:46 kfence_protect
Date: Fri, 18 Nov 2022 10:19:24 +0100 [thread overview]
Message-ID: <Y3dOHNh82NQboctR@elver.google.com> (raw)
In-Reply-To: <41ac24c4-6c95-d946-2679-c1be2cb20536@intel.com>
On Thu, Nov 17, 2022 at 03:54PM -0800, Dave Hansen wrote:
> On 11/17/22 15:23, Marco Elver wrote:
> > Yes - it's the 'level != PG_LEVEL_4K'.
>
> That plus the bisect made it pretty easy to find, thanks for the effort!
>
> Could you double-check that the attached patch fixes it? It seemed to
> for me.
Yes, that works - thanks!
> The issue was that the new "No changes, easy!" check in the suspect
> commit didn't check the cpa->force_split option. It didn't split down
> to 4k and then all hell broke loose.
>
> Oh, and I totally misread the kfence ability to tolerate partial TLB
> flushes. Sorry for the noise there!
> diff --git a/arch/x86/mm/pat/set_memory.c b/arch/x86/mm/pat/set_memory.c
> index 220361ceb997..9b4e2ad957f6 100644
> --- a/arch/x86/mm/pat/set_memory.c
> +++ b/arch/x86/mm/pat/set_memory.c
> @@ -1727,7 +1727,8 @@ static int __change_page_attr_set_clr(struct cpa_data *cpa, int primary)
> /*
> * No changes, easy!
> */
> - if (!(pgprot_val(cpa->mask_set) | pgprot_val(cpa->mask_clr)))
> + if (!(pgprot_val(cpa->mask_set) | pgprot_val(cpa->mask_clr))
> + && !cpa->force_split)
> return ret;
>
> while (rempages) {
Tested-by: Marco Elver <elver@google.com>
next prev parent reply other threads:[~2022-11-18 9:19 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-17 11:31 Naresh Kamboju
2022-11-17 13:58 ` Marco Elver
2022-11-17 14:34 ` Dave Hansen
2022-11-17 23:23 ` Marco Elver
2022-11-17 23:54 ` Dave Hansen
2022-11-18 9:19 ` Marco Elver [this message]
2022-11-18 10:32 ` Peter Zijlstra
2022-11-21 7:28 ` Naresh Kamboju
2022-11-21 8:43 ` Marco Elver
2022-11-21 5:40 ` Naresh Kamboju
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