linux-kernel - Re: [PATCH] mm: slab: Only move management objects off-slab for sizes larger than KMALLOC_MIN

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20151105053139.e38214a9.akpm@linux-foundation.org>
Date:	Thu, 5 Nov 2015 05:31:39 -0800
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Catalin Marinas <catalin.marinas@....com>
Cc:	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	Geert Uytterhoeven <geert@...ux-m68k.org>,
	Christoph Lameter <cl@...ux.com>,
	Pekka Enberg <penberg@...nel.org>,
	David Rientjes <rientjes@...gle.com>,
	Joonsoo Kim <iamjoonsoo.kim@....com>
Subject: Re: [PATCH] mm: slab: Only move management objects off-slab for
 sizes larger than KMALLOC_MIN_SIZE

On Thu,  5 Nov 2015 11:50:35 +0000 Catalin Marinas <catalin.marinas@....com> wrote:

> Commit 8fc9cf420b36 ("slab: make more slab management structure off the
> slab") enables off-slab management objects for sizes starting with
> PAGE_SIZE >> 5. This means 128 bytes for a 4KB page configuration.
> However, on systems with a KMALLOC_MIN_SIZE of 128 (arm64 in 4.4), such
> optimisation does not make sense since the slab management allocation
> would take 128 bytes anyway (even though freelist_size is 32) with the
> additional overhead of another allocation.
> 
> This patch introduces an OFF_SLAB_MIN_SIZE macro which takes
> KMALLOC_MIN_SIZE into account. It also solves a slab bug on arm64 where
> the first kmalloc_cache to be initialised after slab_early_init = 0,
> "kmalloc-128", fails to allocate off-slab management objects from the
> same "kmalloc-128" cache.

That all seems to be quite minor stuff.

> Fixes: 8fc9cf420b36 ("slab: make more slab management structure off the slab")
> Cc: <stable@...r.kernel.org> # 3.15+

Yet you believe the fix should be backported.

So, the usual refrain: when fixing a bug, please describe the end-user
visible effects of that bug.

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/