From: Vlastimil Babka <vbabka@suse.cz>
To: Matteo Rizzo <matteorizzo@google.com>,
"Lameter, Christopher" <cl@os.amperecomputing.com>
Cc: Dave Hansen <dave.hansen@intel.com>,
penberg@kernel.org, rientjes@google.com, iamjoonsoo.kim@lge.com,
akpm@linux-foundation.org, roman.gushchin@linux.dev,
42.hyeyoo@gmail.com, keescook@chromium.org,
linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org,
linux-mm@kvack.org, linux-hardening@vger.kernel.org,
tglx@linutronix.de, mingo@redhat.com, bp@alien8.de,
dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com,
corbet@lwn.net, luto@kernel.org, peterz@infradead.org,
jannh@google.com, evn@google.com, poprdi@google.com,
jordyzomer@google.com, Mike Rapoport <rppt@kernel.org>
Subject: Re: [RFC PATCH 00/14] Prevent cross-cache attacks in the SLUB allocator
Date: Wed, 20 Sep 2023 10:49:50 +0200 [thread overview]
Message-ID: <40bc28e5-c971-055f-eff4-b9d67fe768cc@suse.cz> (raw)
In-Reply-To: <CAHKB1w+rVyww0UrHhzeGfPA7FM482Z-7ApzXvekVqLHvTDAV3Q@mail.gmail.com>
On 9/18/23 14:08, Matteo Rizzo wrote:
> On Fri, 15 Sept 2023 at 18:30, Lameter, Christopher
>> Problems:
>>
>> - Overhead due to more TLB lookups
>>
>> - Larger amounts of TLBs are used for the OS. Currently we are trying to
>> use the maximum mappable TLBs to reduce their numbers. This presumably
>> means using 4K TLBs for all slab access.
>
> Yes, we are using 4K pages for the slab mappings which is going to increase
> TLB pressure. I also tried writing a version of the patch that uses 2M
> pages which had slightly better performance, but that had its own problems.
> For example most slabs are much smaller than 2M, so we would need to create
> and map multiple slabs at once and we wouldn't be able to release the
> physical memory until all slabs in the 2M page are unused which increases
> fragmentation.
At last LSF/MM [1] we basically discarded direct map fragmentation
avoidance as solving something that turns out to be insignificant, with the
exception of kernel code. As kernel code is unlikely to be allocated from
kmem caches due to W^X, we can hopefully assume it's also insignificant for
the virtual slab area.
[1] https://lwn.net/Articles/931406/
prev parent reply other threads:[~2023-09-20 8:49 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-15 10:59 Matteo Rizzo
2023-09-15 10:59 ` [RFC PATCH 01/14] mm/slub: don't try to dereference invalid freepointers Matteo Rizzo
2023-09-15 20:50 ` Kees Cook
2023-09-30 11:04 ` Hyeonggon Yoo
2023-09-15 10:59 ` [RFC PATCH 02/14] mm/slub: add is_slab_addr/is_slab_page helpers Matteo Rizzo
2023-09-15 20:55 ` Kees Cook
2023-09-15 10:59 ` [RFC PATCH 03/14] mm/slub: move kmem_cache_order_objects to slab.h Matteo Rizzo
2023-09-15 20:56 ` Kees Cook
2023-09-15 10:59 ` [RFC PATCH 04/14] mm: use virt_to_slab instead of folio_slab Matteo Rizzo
2023-09-15 20:59 ` Kees Cook
2023-09-15 10:59 ` [RFC PATCH 05/14] mm/slub: create folio_set/clear_slab helpers Matteo Rizzo
2023-09-15 21:02 ` Kees Cook
2023-09-15 10:59 ` [RFC PATCH 06/14] mm/slub: pass additional args to alloc_slab_page Matteo Rizzo
2023-09-15 21:03 ` Kees Cook
2023-09-15 10:59 ` [RFC PATCH 07/14] mm/slub: pass slab pointer to the freeptr decode helper Matteo Rizzo
2023-09-15 21:06 ` Kees Cook
2023-09-15 10:59 ` [RFC PATCH 08/14] security: introduce CONFIG_SLAB_VIRTUAL Matteo Rizzo
2023-09-15 21:07 ` Kees Cook
2023-09-15 10:59 ` [RFC PATCH 09/14] mm/slub: add the slab freelists to kmem_cache Matteo Rizzo
2023-09-15 21:08 ` Kees Cook
2023-09-15 10:59 ` [RFC PATCH 10/14] x86: Create virtual memory region for SLUB Matteo Rizzo
2023-09-15 21:13 ` Kees Cook
2023-09-15 21:49 ` Dave Hansen
2023-09-18 8:54 ` Matteo Rizzo
2023-09-15 10:59 ` [RFC PATCH 11/14] mm/slub: allocate slabs from virtual memory Matteo Rizzo
2023-09-15 21:22 ` Kees Cook
2023-09-15 21:57 ` Dave Hansen
2023-10-11 9:17 ` Matteo Rizzo
2023-09-15 10:59 ` [RFC PATCH 12/14] mm/slub: introduce the deallocated_pages sysfs attribute Matteo Rizzo
2023-09-15 21:23 ` Kees Cook
2023-09-15 10:59 ` [RFC PATCH 13/14] mm/slub: sanity-check freepointers Matteo Rizzo
2023-09-15 21:26 ` Kees Cook
2023-09-15 10:59 ` [RFC PATCH 14/14] security: add documentation for SLAB_VIRTUAL Matteo Rizzo
2023-09-15 21:34 ` Kees Cook
2023-09-20 9:04 ` Vlastimil Babka
2023-09-15 15:19 ` [RFC PATCH 00/14] Prevent cross-cache attacks in the SLUB allocator Dave Hansen
2023-09-15 16:30 ` Lameter, Christopher
2023-09-18 12:08 ` Matteo Rizzo
2023-09-18 17:39 ` Ingo Molnar
2023-09-18 18:05 ` Linus Torvalds
2023-09-19 15:48 ` Matteo Rizzo
2023-09-19 16:02 ` Dave Hansen
2023-09-19 17:56 ` Kees Cook
2023-09-19 18:49 ` Linus Torvalds
2023-09-19 13:42 ` Matteo Rizzo
2023-09-19 15:56 ` Dave Hansen
2023-09-20 7:44 ` Ingo Molnar
2023-09-20 8:49 ` Vlastimil Babka [this message]
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