From: Nadav Amit <nadav.amit@gmail.com>
To: Suren Baghdasaryan <surenb@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
viro@zeniv.linux.org.uk, brauner@kernel.org, shuah@kernel.org,
Andrea Arcangeli <aarcange@redhat.com>,
lokeshgidra@google.com, Peter Xu <peterx@redhat.com>,
David Hildenbrand <david@redhat.com>,
Hugh Dickins <hughd@google.com>,
mhocko@suse.com, Axel Rasmussen <axelrasmussen@google.com>,
Mike Rapoport <rppt@kernel.org>,
Matthew Wilcox <willy@infradead.org>,
Liam.Howlett@oracle.com, Jann Horn <jannh@google.com>,
zhangpeng362@huawei.com, bgeffon@google.com,
kaleshsingh@google.com, ngeoffray@google.com, jdduke@google.com,
linux-mm <linux-mm@kvack.org>,
linux-fsdevel@vger.kernel.org,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
linux-kselftest@vger.kernel.org, kernel-team@android.com
Subject: Re: [PATCH 2/3] userfaultfd: UFFDIO_REMAP uABI
Date: Thu, 14 Sep 2023 14:57:04 -0700 [thread overview]
Message-ID: <4F9BBE45-22D0-4F8D-BA56-CA3459998DC4@gmail.com> (raw)
In-Reply-To: <20230914152620.2743033-3-surenb@google.com>
> On Sep 14, 2023, at 8:26 AM, Suren Baghdasaryan <surenb@google.com> wrote:
>
> + if (!pte_same(ptep_clear_flush(src_vma, src_addr, src_pte),
> + orig_src_pte))
> + BUG_ON(1);
Just a minor detail regarding these few lines:
Besides the less-than-ideal use of BUG_ON() here, I think that this code
assumes that the PTE cannot change at this point. However, as the PTE was
still mapped at this point, I think the access and dirty bits can be set.
tl;dr: this appears to be triggerable by userspace.
[ as for the performance of this code, the lack of batching would mean
that for multithreaded applications where more than a single page is
remapped, performance would suffer ]
next prev parent reply other threads:[~2023-09-14 21:57 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-14 15:26 [PATCH 0/3] userfaultfd remap option Suren Baghdasaryan
2023-09-14 15:26 ` [PATCH 1/3] userfaultfd: UFFDIO_REMAP: rmap preparation Suren Baghdasaryan
2023-09-14 17:56 ` Matthew Wilcox
2023-09-14 18:34 ` Suren Baghdasaryan
2023-09-14 15:26 ` [PATCH 2/3] userfaultfd: UFFDIO_REMAP uABI Suren Baghdasaryan
2023-09-14 18:11 ` Matthew Wilcox
2023-09-14 18:43 ` David Hildenbrand
2023-09-14 18:45 ` David Hildenbrand
2023-09-21 18:04 ` Suren Baghdasaryan
2023-09-21 18:17 ` David Hildenbrand
2023-09-22 1:57 ` Suren Baghdasaryan
2023-09-14 18:47 ` David Hildenbrand
2023-09-14 18:54 ` Suren Baghdasaryan
2023-09-14 19:28 ` Jann Horn
2023-09-14 20:57 ` Suren Baghdasaryan
2023-09-19 23:08 ` Suren Baghdasaryan
2023-09-19 23:40 ` Suren Baghdasaryan
2023-09-19 23:50 ` Jann Horn
2023-09-20 1:49 ` Suren Baghdasaryan
2023-09-20 16:11 ` Jann Horn
2023-09-21 16:59 ` Jann Horn
2023-09-14 21:57 ` Nadav Amit [this message]
2023-09-15 3:28 ` Suren Baghdasaryan
2023-09-15 4:03 ` Nadav Amit
2023-09-15 4:15 ` Suren Baghdasaryan
2023-09-15 23:33 ` Jann Horn
2023-09-15 23:39 ` Suren Baghdasaryan
2023-09-14 15:26 ` [PATCH 3/3] selftests/mm: add UFFDIO_REMAP ioctl test Suren Baghdasaryan
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