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From: Marco Elver <elver@google.com>
To: Jann Horn <jannh@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Alexander Potapenko <glider@google.com>,
	 "H . Peter Anvin" <hpa@zytor.com>,
	"Paul E . McKenney" <paulmck@kernel.org>,
	 Andrey Konovalov <andreyknvl@google.com>,
	Andrey Ryabinin <aryabinin@virtuozzo.com>,
	 Andy Lutomirski <luto@kernel.org>,
	Borislav Petkov <bp@alien8.de>,
	 Catalin Marinas <catalin.marinas@arm.com>,
	Christoph Lameter <cl@linux.com>,
	 Dave Hansen <dave.hansen@linux.intel.com>,
	David Rientjes <rientjes@google.com>,
	 Dmitry Vyukov <dvyukov@google.com>,
	Eric Dumazet <edumazet@google.com>,
	 Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Hillf Danton <hdanton@sina.com>,  Ingo Molnar <mingo@redhat.com>,
	Jonathan Cameron <Jonathan.Cameron@huawei.com>,
	 Jonathan Corbet <corbet@lwn.net>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	 Kees Cook <keescook@chromium.org>,
	Mark Rutland <mark.rutland@arm.com>,
	 Pekka Enberg <penberg@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	 SeongJae Park <sjpark@amazon.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Vlastimil Babka <vbabka@suse.cz>,  Will Deacon <will@kernel.org>,
	"the arch/x86 maintainers" <x86@kernel.org>,
	 "open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
	kernel list <linux-kernel@vger.kernel.org>,
	 kasan-dev <kasan-dev@googlegroups.com>,
	 Linux ARM <linux-arm-kernel@lists.infradead.org>,
	Linux-MM <linux-mm@kvack.org>,  SeongJae Park <sjpark@amazon.de>
Subject: Re: [PATCH v4 01/11] mm: add Kernel Electric-Fence infrastructure
Date: Fri, 2 Oct 2020 23:28:12 +0200	[thread overview]
Message-ID: <CANpmjNN7s3o4DYbP64iLYo0MeDWciQnKd61njJKLsiZv+ZLQdA@mail.gmail.com> (raw)
In-Reply-To: <CAG48ez0D1+hStZaDOigwbqNqFHJAJtXK+8Nadeuiu1Byv+xp5A@mail.gmail.com>

On Fri, 2 Oct 2020 at 21:32, Jann Horn <jannh@google.com> wrote:

> > That's another check; we don't want to make this more expensive.
>
> Ah, right, I missed that this is the one piece of KFENCE that is
> actually really hot code until Dmitry pointed that out.
>
> But actually, can't you reduce how hot this is for SLUB by moving
> is_kfence_address() down into the freeing slowpath? At the moment you
> use it in slab_free_freelist_hook(), which is in the super-hot
> fastpath, but you should be able to at least move it down into
> __slab_free()...
>
> Actually, you already have hooked into __slab_free(), so can't you
> just get rid of the check in the slab_free_freelist_hook()?

I missed this bit: the loop that follows wants the free pointer, so I
currently see how this might work. :-/

We'll look at your other email re optimizing is_kfence_address() next
week; and thank you for the detailed comments thus far!

Thanks,
-- Marco


  parent reply	other threads:[~2020-10-02 21:28 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-29 13:38 [PATCH v4 00/11] KFENCE: A low-overhead sampling-based memory safety error detector Marco Elver
2020-09-29 13:38 ` [PATCH v4 01/11] mm: add Kernel Electric-Fence infrastructure Marco Elver
2020-10-02  6:33   ` Jann Horn
2020-10-02  7:53     ` Jann Horn
2020-10-02 14:22       ` Dmitry Vyukov
2020-10-02 15:06         ` Mark Rutland
2020-10-02 18:27         ` Jann Horn
2020-10-05 18:59           ` Marco Elver
2020-10-02 17:19     ` Marco Elver
2020-10-02 19:31       ` Jann Horn
2020-10-02 21:12         ` Marco Elver
2020-10-02 21:28         ` Marco Elver [this message]
2020-10-02 22:27           ` Jann Horn
2020-10-12 14:20             ` Marco Elver
2020-09-29 13:38 ` [PATCH v4 02/11] x86, kfence: enable KFENCE for x86 Marco Elver
2020-10-02  5:45   ` Jann Horn
2020-10-07 13:08     ` Marco Elver
2020-10-07 14:14       ` Jann Horn
2020-10-07 14:41         ` Marco Elver
2020-10-09 17:40           ` Marco Elver
2020-10-02  6:08   ` Jann Horn
2020-09-29 13:38 ` [PATCH v4 03/11] arm64, kfence: enable KFENCE for ARM64 Marco Elver
2020-10-02  6:47   ` Jann Horn
2020-10-02 14:18     ` Marco Elver
2020-10-02 16:10       ` Jann Horn
2020-09-29 13:38 ` [PATCH v4 04/11] mm, kfence: insert KFENCE hooks for SLAB Marco Elver
2020-09-29 13:38 ` [PATCH v4 05/11] mm, kfence: insert KFENCE hooks for SLUB Marco Elver
2020-10-02  7:07   ` Jann Horn
2020-10-05  9:29     ` Alexander Potapenko
2020-09-29 13:38 ` [PATCH v4 06/11] kfence, kasan: make KFENCE compatible with KASAN Marco Elver
2020-09-29 13:38 ` [PATCH v4 07/11] kfence, kmemleak: make KFENCE compatible with KMEMLEAK Marco Elver
2020-09-29 13:38 ` [PATCH v4 08/11] kfence, lockdep: make KFENCE compatible with lockdep Marco Elver
2020-09-29 13:38 ` [PATCH v4 09/11] kfence, Documentation: add KFENCE documentation Marco Elver
2020-09-29 13:38 ` [PATCH v4 10/11] kfence: add test suite Marco Elver
2020-09-29 13:38 ` [PATCH v4 11/11] MAINTAINERS: Add entry for KFENCE Marco Elver
2020-09-29 14:21   ` SeongJae Park

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