From: Qi Zheng <zhengqi.arch@bytedance.com>
To: Matthew Wilcox <willy@infradead.org>,
David Hildenbrand <david@redhat.com>
Cc: linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, songmuchun@bytedance.com,
zhouchengming@bytedance.com, akpm@linux-foundation.org,
tglx@linutronix.de, kirill.shutemov@linux.intel.com,
jgg@nvidia.com, tj@kernel.org, dennis@kernel.org,
ming.lei@redhat.com
Subject: Re: [RFC PATCH 00/18] Try to free user PTE page table pages
Date: Thu, 19 May 2022 12:03:41 +0800 [thread overview]
Message-ID: <94047220-1991-078f-3a2c-21ccbcb1eafc@bytedance.com> (raw)
In-Reply-To: <YoUJEZU9JcfMlhRO@casper.infradead.org>
On 2022/5/18 10:56 PM, Matthew Wilcox wrote:
> On Wed, May 18, 2022 at 04:51:06PM +0200, David Hildenbrand wrote:
>> yes, I talked about the involved challenges, especially, how malicious
>> user space can trigger allocation of almost elusively page tables and
>> essentially consume a lot of unmovable+unswappable memory and even store
>> secrets in the page table structure.
>
> There are a lot of ways for userspace to consume a large amount of
> kernel memory. For example, one can open a file and set file locks on
Yes, malicious programs are really hard to avoid, maybe we should try to
solve some common cases first (such as empty PTE tables).
> alternate bytes. We generally handle this by accounting the memory to
> the process and let the OOM killer, rlimits, memcg or other mechanism
> take care of it. Just because page tables are (generally) reclaimable
> doesn't mean we need to treat them specially.
>
--
Thanks,
Qi
next prev parent reply other threads:[~2022-05-19 4:03 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-29 13:35 Qi Zheng
2022-04-29 13:35 ` [RFC PATCH 01/18] x86/mm/encrypt: add the missing pte_unmap() call Qi Zheng
2022-04-29 13:35 ` [RFC PATCH 02/18] percpu_ref: make ref stable after percpu_ref_switch_to_atomic_sync() returns Qi Zheng
2022-04-29 13:35 ` [RFC PATCH 03/18] percpu_ref: make percpu_ref_switch_lock per percpu_ref Qi Zheng
2022-04-29 13:35 ` [RFC PATCH 04/18] mm: convert to use ptep_clear() in pte_clear_not_present_full() Qi Zheng
2022-04-29 13:35 ` [RFC PATCH 05/18] mm: split the related definitions of pte_offset_map_lock() into pgtable.h Qi Zheng
2022-04-29 13:35 ` [RFC PATCH 06/18] mm: introduce CONFIG_FREE_USER_PTE Qi Zheng
2022-04-29 13:35 ` [RFC PATCH 07/18] mm: add pte_to_page() helper Qi Zheng
2022-04-29 13:35 ` [RFC PATCH 08/18] mm: introduce percpu_ref for user PTE page table page Qi Zheng
2022-04-29 13:35 ` [RFC PATCH 09/18] pte_ref: add pte_tryget() and {__,}pte_put() helper Qi Zheng
2022-04-29 13:35 ` [RFC PATCH 10/18] mm: add pte_tryget_map{_lock}() helper Qi Zheng
2022-04-29 13:35 ` [RFC PATCH 11/18] mm: convert to use pte_tryget_map_lock() Qi Zheng
2022-04-29 13:35 ` [RFC PATCH 12/18] mm: convert to use pte_tryget_map() Qi Zheng
2022-04-29 13:35 ` [RFC PATCH 13/18] mm: add try_to_free_user_pte() helper Qi Zheng
2022-04-30 13:35 ` Qi Zheng
2022-04-29 13:35 ` [RFC PATCH 14/18] mm: use try_to_free_user_pte() in MADV_DONTNEED case Qi Zheng
2022-04-29 13:35 ` [RFC PATCH 15/18] mm: use try_to_free_user_pte() in MADV_FREE case Qi Zheng
2022-04-29 13:35 ` [RFC PATCH 16/18] pte_ref: add track_pte_{set, clear}() helper Qi Zheng
2022-04-29 13:35 ` [RFC PATCH 17/18] x86/mm: add x86_64 support for pte_ref Qi Zheng
2022-04-29 13:35 ` [RFC PATCH 18/18] Documentation: add document " Qi Zheng
2022-04-30 13:19 ` Bagas Sanjaya
2022-04-30 13:32 ` Qi Zheng
2022-05-17 8:30 ` [RFC PATCH 00/18] Try to free user PTE page table pages Qi Zheng
2022-05-18 14:51 ` David Hildenbrand
2022-05-18 14:56 ` Matthew Wilcox
2022-05-19 4:03 ` Qi Zheng [this message]
2022-05-19 3:58 ` Qi Zheng
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