From: Peter Xu <peterx@redhat.com>
To: Axel Rasmussen <axelrasmussen@google.com>
Cc: "Alexander Viro" <viro@zeniv.linux.org.uk>,
"Alexey Dobriyan" <adobriyan@gmail.com>,
"Andrea Arcangeli" <aarcange@redhat.com>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Anshuman Khandual" <anshuman.khandual@arm.com>,
"Catalin Marinas" <catalin.marinas@arm.com>,
"Chinwen Chang" <chinwen.chang@mediatek.com>,
"Huang Ying" <ying.huang@intel.com>,
"Ingo Molnar" <mingo@redhat.com>, "Jann Horn" <jannh@google.com>,
"Jerome Glisse" <jglisse@redhat.com>,
"Lokesh Gidra" <lokeshgidra@google.com>,
"Matthew Wilcox (Oracle)" <willy@infradead.org>,
"Michael Ellerman" <mpe@ellerman.id.au>,
"Michal Koutný" <mkoutny@suse.com>,
"Michel Lespinasse" <walken@google.com>,
"Mike Kravetz" <mike.kravetz@oracle.com>,
"Mike Rapoport" <rppt@linux.vnet.ibm.com>,
"Nicholas Piggin" <npiggin@gmail.com>, "Shaohua Li" <shli@fb.com>,
"Shawn Anastasio" <shawn@anastas.io>,
"Steven Rostedt" <rostedt@goodmis.org>,
"Steven Price" <steven.price@arm.com>,
"Vlastimil Babka" <vbabka@suse.cz>,
LKML <linux-kernel@vger.kernel.org>,
linux-fsdevel@vger.kernel.org, "Linux MM" <linux-mm@kvack.org>,
"Adam Ruprecht" <ruprecht@google.com>,
"Cannon Matthews" <cannonmatthews@google.com>,
"Dr . David Alan Gilbert" <dgilbert@redhat.com>,
"David Rientjes" <rientjes@google.com>,
"Oliver Upton" <oupton@google.com>
Subject: Re: [PATCH 0/9] userfaultfd: add minor fault handling
Date: Thu, 21 Jan 2021 17:37:03 -0500 [thread overview]
Message-ID: <20210121223703.GH260413@xz-x1> (raw)
In-Reply-To: <CAJHvVch3iK_UcwpwL5p3LWQAZo_iyLMVxsMTf_GCAStqoQxmTA@mail.gmail.com>
On Thu, Jan 21, 2021 at 02:13:50PM -0800, Axel Rasmussen wrote:
> When I wrote this, my thinking was that users of this feature would
> have two mappings, one of which is not UFFD registered at all. So, to
> replace the existing page contents, userspace would just write to the
> non-UFFD mapping (with memcpy() or whatever else, or we could get
> fancy and imagine using some RDMA technology to copy the page over the
> network from the live migration source directly in place). After
> performing the write, we just UFFDIO_CONTINUE.
>
> I believe FALLOC_FL_PUNCH_HOLE / MADV_REMOVE doesn't work with
> hugetlbfs? Once shmem support is implemented, I would expect
> FALLOC_FL_PUNCH_HOLE + UFFDIO_COPY to work, but I wonder if such an
> operation would be more expensive than just copying using the other
> side of the shared mapping?
IIUC hugetlb supports that (hugetlbfs_punch_hole()). But I agree with you on
what you said should be good enough. Thanks,
--
Peter Xu
next prev parent reply other threads:[~2021-01-21 22:38 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-15 19:04 [PATCH 0/9] userfaultfd: add minor fault handling Axel Rasmussen
2021-01-15 19:04 ` [PATCH 1/9] hugetlb: Pass vma into huge_pte_alloc() Axel Rasmussen
2021-01-15 19:04 ` [PATCH 2/9] hugetlb/userfaultfd: Forbid huge pmd sharing when uffd enabled Axel Rasmussen
2021-01-21 18:52 ` Peter Xu
2021-01-15 19:04 ` [PATCH 3/9] mm/hugetlb: Move flush_hugetlb_tlb_range() into hugetlb.h Axel Rasmussen
2021-01-15 19:04 ` [PATCH 4/9] hugetlb/userfaultfd: Unshare all pmds for hugetlbfs when register wp Axel Rasmussen
2021-01-15 19:04 ` [PATCH 5/9] userfaultfd: add minor fault registration mode Axel Rasmussen
2021-01-21 18:49 ` Peter Xu
2021-01-15 19:04 ` [PATCH 6/9] userfaultfd: disable huge PMD sharing for MINOR registered VMAs Axel Rasmussen
2021-01-21 18:59 ` Peter Xu
2021-01-15 19:04 ` [PATCH 7/9] userfaultfd: add UFFDIO_CONTINUE ioctl Axel Rasmussen
2021-01-21 22:46 ` Peter Xu
2021-01-21 23:46 ` Axel Rasmussen
2021-01-15 19:04 ` [PATCH 8/9] userfaultfd: update documentation to describe minor fault handling Axel Rasmussen
2021-01-15 19:04 ` [PATCH 9/9] userfaultfd/selftests: add test exercising " Axel Rasmussen
2021-01-21 19:12 ` [PATCH 0/9] userfaultfd: add " Peter Xu
2021-01-21 22:13 ` Axel Rasmussen
2021-01-21 22:37 ` Peter Xu [this message]
2021-01-22 21:29 Axel Rasmussen
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