From: David Hildenbrand <david@redhat.com> To: Jason Gunthorpe <jgg@ziepe.ca> Cc: Sean Christopherson <seanjc@google.com>, Andy Lutomirski <luto@kernel.org>, Chao Peng <chao.p.peng@linux.intel.com>, kvm list <kvm@vger.kernel.org>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, Linux API <linux-api@vger.kernel.org>, qemu-devel@nongnu.org, Paolo Bonzini <pbonzini@redhat.com>, Jonathan Corbet <corbet@lwn.net>, Vitaly Kuznetsov <vkuznets@redhat.com>, Wanpeng Li <wanpengli@tencent.com>, Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>, Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>, the arch/x86 maintainers <x86@kernel.org>, "H. Peter Anvin" <hpa@zytor.com>, Hugh Dickins <hughd@google.com>, Jeff Layton <jlayton@kernel.org>, "J . Bruce Fields" <bfields@fieldses.org>, Andrew Morton <akpm@linux-foundation.org>, Mike Rapoport <rppt@kernel.org>, Steven Price <steven.price@arm.com>, "Maciej S . Szmigiero" <mail@maciej.szmigiero.name>, Vlastimil Babka <vbabka@suse.cz>, Vishal Annapurve <vannapurve@google.com>, Yu Zhang <yu.c.zhang@linux.intel.com>, "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>, "Nakajima, Jun" <jun.nakajima@intel.com>, Dave Hansen <dave.hansen@intel.com>, Andi Kleen <ak@linux.intel.com> Subject: Re: [PATCH v5 04/13] mm/shmem: Restrict MFD_INACCESSIBLE memory against RLIMIT_MEMLOCK Date: Wed, 13 Apr 2022 18:24:56 +0200 [thread overview] Message-ID: <1686fd2d-d9c3-ec12-32df-8c4c5ae26b08@redhat.com> (raw) In-Reply-To: <20220412143636.GG64706@ziepe.ca> On 12.04.22 16:36, Jason Gunthorpe wrote: > On Fri, Apr 08, 2022 at 08:54:02PM +0200, David Hildenbrand wrote: > >> RLIMIT_MEMLOCK was the obvious candidate, but as we discovered int he >> past already with secretmem, it's not 100% that good of a fit (unmovable >> is worth than mlocked). But it gets the job done for now at least. > > No, it doesn't. There are too many different interpretations how > MELOCK is supposed to work > > eg VFIO accounts per-process so hostile users can just fork to go past > it. > > RDMA is per-process but uses a different counter, so you can double up > > iouring is per-user and users a 3rd counter, so it can triple up on > the above two Thanks for that summary, very helpful. > >> So I'm open for alternative to limit the amount of unmovable memory we >> might allocate for user space, and then we could convert seretmem as well. > > I think it has to be cgroup based considering where we are now :\ Most probably. I think the important lessons we learned are that * mlocked != unmovable. * RLIMIT_MEMLOCK should most probably never have been abused for unmovable memory (especially, long-term pinning) -- Thanks, David / dhildenb
WARNING: multiple messages have this Message-ID (diff)
From: David Hildenbrand <david@redhat.com> To: Jason Gunthorpe <jgg@ziepe.ca> Cc: Wanpeng Li <wanpengli@tencent.com>, "Nakajima, Jun" <jun.nakajima@intel.com>, kvm list <kvm@vger.kernel.org>, qemu-devel@nongnu.org, "J . Bruce Fields" <bfields@fieldses.org>, linux-mm@kvack.org, "H. Peter Anvin" <hpa@zytor.com>, Chao Peng <chao.p.peng@linux.intel.com>, Andi Kleen <ak@linux.intel.com>, Jonathan Corbet <corbet@lwn.net>, Joerg Roedel <joro@8bytes.org>, the arch/x86 maintainers <x86@kernel.org>, Hugh Dickins <hughd@google.com>, Steven Price <steven.price@arm.com>, Ingo Molnar <mingo@redhat.com>, "Maciej S . Szmigiero" <mail@maciej.szmigiero.name>, Borislav Petkov <bp@alien8.de>, Andy Lutomirski <luto@kernel.org>, Thomas Gleixner <tglx@linutronix.de>, Andrew Morton <akpm@linux-foundation.org>, Vlastimil Babka <vbabka@suse.cz>, Jim Mattson <jmattson@google.com>, Dave Hansen <dave.hansen@intel.com>, Sean Christopherson <seanjc@google.com>, Jeff Layton <jlayton@kernel.org>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, Yu Zhang <yu.c.zhang@linux.intel.com>, "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>, Linux API <linux-api@vger.kernel.org>, linux-fsdevel@vger.kernel.org, Paolo Bonzini <pbonzini@redhat.com>, Vitaly Kuznetsov <vkuznets@redhat.com>, Vishal Annapurve <vannapurve@google.com>, Mike Rapoport <rppt@kernel.org> Subject: Re: [PATCH v5 04/13] mm/shmem: Restrict MFD_INACCESSIBLE memory against RLIMIT_MEMLOCK Date: Wed, 13 Apr 2022 18:24:56 +0200 [thread overview] Message-ID: <1686fd2d-d9c3-ec12-32df-8c4c5ae26b08@redhat.com> (raw) In-Reply-To: <20220412143636.GG64706@ziepe.ca> On 12.04.22 16:36, Jason Gunthorpe wrote: > On Fri, Apr 08, 2022 at 08:54:02PM +0200, David Hildenbrand wrote: > >> RLIMIT_MEMLOCK was the obvious candidate, but as we discovered int he >> past already with secretmem, it's not 100% that good of a fit (unmovable >> is worth than mlocked). But it gets the job done for now at least. > > No, it doesn't. There are too many different interpretations how > MELOCK is supposed to work > > eg VFIO accounts per-process so hostile users can just fork to go past > it. > > RDMA is per-process but uses a different counter, so you can double up > > iouring is per-user and users a 3rd counter, so it can triple up on > the above two Thanks for that summary, very helpful. > >> So I'm open for alternative to limit the amount of unmovable memory we >> might allocate for user space, and then we could convert seretmem as well. > > I think it has to be cgroup based considering where we are now :\ Most probably. I think the important lessons we learned are that * mlocked != unmovable. * RLIMIT_MEMLOCK should most probably never have been abused for unmovable memory (especially, long-term pinning) -- Thanks, David / dhildenb
next prev parent reply other threads:[~2022-04-13 16:25 UTC|newest] Thread overview: 183+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-03-10 14:08 [PATCH v5 00/13] KVM: mm: fd-based approach for supporting KVM guest private memory Chao Peng 2022-03-10 14:08 ` Chao Peng 2022-03-10 14:08 ` [PATCH v5 01/13] mm/memfd: Introduce MFD_INACCESSIBLE flag Chao Peng 2022-03-10 14:08 ` Chao Peng 2022-04-11 15:10 ` Kirill A. Shutemov 2022-04-11 15:10 ` Kirill A. Shutemov 2022-04-12 13:11 ` Chao Peng 2022-04-12 13:11 ` Chao Peng 2022-04-23 5:43 ` Vishal Annapurve 2022-04-24 8:15 ` Chao Peng 2022-04-24 8:15 ` Chao Peng 2022-03-10 14:09 ` [PATCH v5 02/13] mm: Introduce memfile_notifier Chao Peng 2022-03-10 14:09 ` Chao Peng 2022-03-29 18:45 ` Sean Christopherson 2022-04-08 12:54 ` Chao Peng 2022-04-08 12:54 ` Chao Peng 2022-04-12 14:36 ` Hillf Danton 2022-04-13 6:47 ` Chao Peng 2022-03-10 14:09 ` [PATCH v5 03/13] mm/shmem: Support memfile_notifier Chao Peng 2022-03-10 14:09 ` Chao Peng 2022-03-10 23:08 ` Dave Chinner 2022-03-10 23:08 ` Dave Chinner 2022-03-11 8:42 ` Chao Peng 2022-03-11 8:42 ` Chao Peng 2022-04-11 15:26 ` Kirill A. Shutemov 2022-04-11 15:26 ` Kirill A. Shutemov 2022-04-12 13:12 ` Chao Peng 2022-04-12 13:12 ` Chao Peng 2022-04-19 22:40 ` Vishal Annapurve 2022-04-20 3:24 ` Chao Peng 2022-04-20 3:24 ` Chao Peng 2022-03-10 14:09 ` [PATCH v5 04/13] mm/shmem: Restrict MFD_INACCESSIBLE memory against RLIMIT_MEMLOCK Chao Peng 2022-03-10 14:09 ` Chao Peng 2022-04-07 16:05 ` Sean Christopherson 2022-04-07 17:09 ` Andy Lutomirski 2022-04-07 17:09 ` Andy Lutomirski 2022-04-08 17:56 ` Sean Christopherson 2022-04-08 18:54 ` David Hildenbrand 2022-04-08 18:54 ` David Hildenbrand 2022-04-12 14:36 ` Jason Gunthorpe 2022-04-12 14:36 ` Jason Gunthorpe 2022-04-12 21:27 ` Andy Lutomirski 2022-04-12 21:27 ` Andy Lutomirski 2022-04-13 16:30 ` David Hildenbrand 2022-04-13 16:30 ` David Hildenbrand 2022-04-13 16:24 ` David Hildenbrand [this message] 2022-04-13 16:24 ` David Hildenbrand 2022-04-13 17:52 ` Jason Gunthorpe 2022-04-13 17:52 ` Jason Gunthorpe 2022-04-25 14:07 ` David Hildenbrand 2022-04-25 14:07 ` David Hildenbrand 2022-04-08 13:02 ` Chao Peng 2022-04-08 13:02 ` Chao Peng 2022-04-11 15:34 ` Kirill A. Shutemov 2022-04-11 15:34 ` Kirill A. Shutemov 2022-04-12 5:14 ` Hugh Dickins 2022-04-11 15:32 ` Kirill A. Shutemov 2022-04-11 15:32 ` Kirill A. Shutemov 2022-04-12 13:39 ` Chao Peng 2022-04-12 13:39 ` Chao Peng 2022-04-12 19:28 ` Kirill A. Shutemov 2022-04-12 19:28 ` Kirill A. Shutemov 2022-04-13 9:15 ` Chao Peng 2022-04-13 9:15 ` Chao Peng 2022-03-10 14:09 ` [PATCH v5 05/13] KVM: Extend the memslot to support fd-based private memory Chao Peng 2022-03-10 14:09 ` Chao Peng 2022-03-28 21:27 ` Sean Christopherson 2022-04-08 13:21 ` Chao Peng 2022-04-08 13:21 ` Chao Peng 2022-03-28 21:56 ` Sean Christopherson 2022-04-08 13:46 ` Chao Peng 2022-04-08 13:46 ` Chao Peng 2022-04-08 17:45 ` Sean Christopherson 2022-03-10 14:09 ` [PATCH v5 06/13] KVM: Use kvm_userspace_memory_region_ext Chao Peng 2022-03-10 14:09 ` Chao Peng 2022-03-28 22:26 ` Sean Christopherson 2022-04-08 13:58 ` Chao Peng 2022-04-08 13:58 ` Chao Peng 2022-03-10 14:09 ` [PATCH v5 07/13] KVM: Add KVM_EXIT_MEMORY_ERROR exit Chao Peng 2022-03-10 14:09 ` Chao Peng 2022-03-28 22:33 ` Sean Christopherson 2022-04-08 13:59 ` Chao Peng 2022-04-08 13:59 ` Chao Peng 2022-03-10 14:09 ` [PATCH v5 08/13] KVM: Use memfile_pfn_ops to obtain pfn for private pages Chao Peng 2022-03-10 14:09 ` Chao Peng 2022-03-28 23:56 ` Sean Christopherson 2022-04-08 14:07 ` Chao Peng 2022-04-08 14:07 ` Chao Peng 2022-04-28 12:37 ` Chao Peng 2022-04-28 12:37 ` Chao Peng 2022-03-10 14:09 ` [PATCH v5 09/13] KVM: Handle page fault for private memory Chao Peng 2022-03-10 14:09 ` Chao Peng 2022-03-29 1:07 ` Sean Christopherson 2022-04-12 12:10 ` Chao Peng 2022-04-12 12:10 ` Chao Peng 2022-03-10 14:09 ` [PATCH v5 10/13] KVM: Register private memslot to memory backing store Chao Peng 2022-03-10 14:09 ` Chao Peng 2022-03-29 19:01 ` Sean Christopherson 2022-04-12 12:40 ` Chao Peng 2022-04-12 12:40 ` Chao Peng 2022-03-10 14:09 ` [PATCH v5 11/13] KVM: Zap existing KVM mappings when pages changed in the private fd Chao Peng 2022-03-10 14:09 ` Chao Peng 2022-03-29 19:23 ` Sean Christopherson 2022-04-12 12:43 ` Chao Peng 2022-04-12 12:43 ` Chao Peng 2022-04-05 23:45 ` Michael Roth 2022-04-08 3:06 ` Sean Christopherson 2022-04-19 22:43 ` Vishal Annapurve 2022-04-20 3:17 ` Chao Peng 2022-04-20 3:17 ` Chao Peng 2022-03-10 14:09 ` [PATCH v5 12/13] KVM: Expose KVM_MEM_PRIVATE Chao Peng 2022-03-10 14:09 ` Chao Peng 2022-03-29 19:13 ` Sean Christopherson 2022-04-12 12:56 ` Chao Peng 2022-04-12 12:56 ` Chao Peng 2022-03-10 14:09 ` [PATCH v5 13/13] memfd_create.2: Describe MFD_INACCESSIBLE flag Chao Peng 2022-03-10 14:09 ` Chao Peng 2022-03-24 15:51 ` [PATCH v5 00/13] KVM: mm: fd-based approach for supporting KVM guest private memory Quentin Perret 2022-03-28 17:13 ` Sean Christopherson 2022-03-28 18:00 ` Quentin Perret 2022-03-28 18:58 ` Sean Christopherson 2022-03-29 17:01 ` Quentin Perret 2022-03-30 8:58 ` Steven Price 2022-03-30 8:58 ` Steven Price 2022-03-30 10:39 ` Quentin Perret 2022-03-30 17:58 ` Sean Christopherson 2022-03-31 16:04 ` Andy Lutomirski 2022-03-31 16:04 ` Andy Lutomirski 2022-04-01 14:59 ` Quentin Perret 2022-04-01 17:14 ` Sean Christopherson 2022-04-01 18:03 ` Quentin Perret 2022-04-01 18:24 ` Sean Christopherson 2022-04-01 19:56 ` Andy Lutomirski 2022-04-01 19:56 ` Andy Lutomirski 2022-04-04 15:01 ` Quentin Perret 2022-04-04 17:06 ` Sean Christopherson 2022-04-04 22:04 ` Andy Lutomirski 2022-04-04 22:04 ` Andy Lutomirski 2022-04-05 10:36 ` Quentin Perret 2022-04-05 17:51 ` Andy Lutomirski 2022-04-05 17:51 ` Andy Lutomirski 2022-04-05 18:30 ` Sean Christopherson 2022-04-06 18:42 ` Andy Lutomirski 2022-04-06 18:42 ` Andy Lutomirski 2022-04-06 13:05 ` Quentin Perret 2022-04-05 18:03 ` Sean Christopherson 2022-04-06 10:34 ` Quentin Perret 2022-04-22 10:56 ` Chao Peng 2022-04-22 10:56 ` Chao Peng 2022-04-22 11:06 ` Paolo Bonzini 2022-04-22 11:06 ` Paolo Bonzini 2022-04-24 8:07 ` Chao Peng 2022-04-24 8:07 ` Chao Peng 2022-04-24 16:59 ` Andy Lutomirski 2022-04-24 16:59 ` Andy Lutomirski 2022-04-25 13:40 ` Chao Peng 2022-04-25 13:40 ` Chao Peng 2022-04-25 14:52 ` Andy Lutomirski 2022-04-25 14:52 ` Andy Lutomirski 2022-04-25 20:30 ` Sean Christopherson 2022-06-10 19:18 ` Andy Lutomirski 2022-06-10 19:27 ` Sean Christopherson 2022-04-28 12:29 ` Chao Peng 2022-04-28 12:29 ` Chao Peng 2022-05-03 11:12 ` Quentin Perret 2022-05-09 22:30 ` Michael Roth 2022-05-09 23:29 ` Sean Christopherson 2022-07-21 20:05 ` Gupta, Pankaj 2022-07-21 21:19 ` Sean Christopherson 2022-07-21 21:36 ` Gupta, Pankaj 2022-07-23 3:09 ` Andy Lutomirski 2022-07-25 9:19 ` Gupta, Pankaj 2022-03-30 16:18 ` Sean Christopherson 2022-03-28 20:16 ` Andy Lutomirski 2022-03-28 20:16 ` Andy Lutomirski 2022-03-28 22:48 ` Nakajima, Jun 2022-03-28 22:48 ` Nakajima, Jun 2022-03-29 0:04 ` Sean Christopherson 2022-04-08 21:35 ` Vishal Annapurve 2022-04-12 13:00 ` Chao Peng 2022-04-12 13:00 ` Chao Peng 2022-04-12 19:58 ` Kirill A. Shutemov 2022-04-12 19:58 ` Kirill A. Shutemov
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