From: Alexander Potapenko <glider@google.com>
To: Marco Elver <elver@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Dmitriy Vyukov <dvyukov@google.com>,
Andrey Konovalov <andreyknvl@google.com>,
Jann Horn <jannh@google.com>,
LKML <linux-kernel@vger.kernel.org>,
Linux Memory Management List <linux-mm@kvack.org>,
kasan-dev <kasan-dev@googlegroups.com>,
"the arch/x86 maintainers" <x86@kernel.org>,
Tomi Sarvela <tomi.p.sarvela@intel.com>
Subject: Re: [PATCH mm] kfence, x86: fix preemptible warning on KPTI-enabled systems
Date: Thu, 1 Apr 2021 11:11:19 +0200 [thread overview]
Message-ID: <CAG_fn=W7WZBCSozOuMWzr52Ri_htrmkTOkcF5nvMs9icH=StoA@mail.gmail.com> (raw)
In-Reply-To: <20210330065737.652669-1-elver@google.com>
On Tue, Mar 30, 2021 at 8:57 AM Marco Elver <elver@google.com> wrote:
>
> On systems with KPTI enabled, we can currently observe the following warning:
>
> BUG: using smp_processor_id() in preemptible
> caller is invalidate_user_asid+0x13/0x50
> CPU: 6 PID: 1075 Comm: dmesg Not tainted 5.12.0-rc4-gda4a2b1a5479-kfence_1+ #1
> Hardware name: Hewlett-Packard HP Pro 3500 Series/2ABF, BIOS 8.11 10/24/2012
> Call Trace:
> dump_stack+0x7f/0xad
> check_preemption_disabled+0xc8/0xd0
> invalidate_user_asid+0x13/0x50
> flush_tlb_one_kernel+0x5/0x20
> kfence_protect+0x56/0x80
> ...
>
> While it normally makes sense to require preemption to be off, so that
> the expected CPU's TLB is flushed and not another, in our case it really
> is best-effort (see comments in kfence_protect_page()).
>
> Avoid the warning by disabling preemption around flush_tlb_one_kernel().
>
> Link: https://lore.kernel.org/lkml/YGIDBAboELGgMgXy@elver.google.com/
> Reported-by: Tomi Sarvela <tomi.p.sarvela@intel.com>
> Signed-off-by: Marco Elver <elver@google.com>
Acked-by: Alexander Potapenko <glider@google.com>
prev parent reply other threads:[~2021-04-01 9:11 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-30 6:57 Marco Elver
2021-04-01 9:11 ` Alexander Potapenko [this message]
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