From: Dave Hansen <dave.hansen@intel.com>
To: Marco Elver <elver@google.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: Thu, 17 Nov 2022 15:54:21 -0800 [thread overview]
Message-ID: <41ac24c4-6c95-d946-2679-c1be2cb20536@intel.com> (raw)
In-Reply-To: <Y3bCV6VckVUEF7Pq@elver.google.com>
[-- Attachment #1: Type: text/plain, Size: 517 bytes --]
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.
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!
[-- Attachment #2: kfence.patch --]
[-- Type: text/x-patch, Size: 505 bytes --]
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) {
next prev parent reply other threads:[~2022-11-17 23:55 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 [this message]
2022-11-18 9:19 ` Marco Elver
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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