From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: akpm@linux-foundation.org, dan.j.williams@intel.com,
mhocko@suse.com, keith.busch@intel.com,
kirill.shutemov@linux.intel.com,
alexander.h.duyck@linux.intel.com, ira.weiny@intel.com,
andreyknvl@google.com, arunks@codeaurora.org, vbabka@suse.cz,
cl@linux.com, riel@surriel.com, keescook@chromium.org,
hannes@cmpxchg.org, npiggin@gmail.com,
mathieu.desnoyers@efficios.com, shakeelb@google.com, guro@fb.com,
aarcange@redhat.com, hughd@google.com, jglisse@redhat.com,
mgorman@techsingularity.net, daniel.m.jordan@oracle.com,
jannh@google.com, kilobyte@angband.pl, linux-api@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH v2 0/7] mm: process_vm_mmap() -- syscall for duplication a process mapping
Date: Wed, 22 May 2019 18:22:54 +0300 [thread overview]
Message-ID: <20190522152254.5cyxhjizuwuojlix@box> (raw)
In-Reply-To: <155836064844.2441.10911127801797083064.stgit@localhost.localdomain>
On Mon, May 20, 2019 at 05:00:01PM +0300, Kirill Tkhai wrote:
> This patchset adds a new syscall, which makes possible
> to clone a VMA from a process to current process.
> The syscall supplements the functionality provided
> by process_vm_writev() and process_vm_readv() syscalls,
> and it may be useful in many situation.
Kirill, could you explain how the change affects rmap and how it is safe.
My concern is that the patchset allows to map the same page multiple times
within one process or even map page allocated by child to the parrent.
It was not allowed before.
In the best case it makes reasoning about rmap substantially more difficult.
But I'm worry it will introduce hard-to-debug bugs, like described in
https://lwn.net/Articles/383162/.
Note, that is some cases we care about rmap walk order (see for instance
mremap() case). I'm not convinced that the feature will not break
something in the area.
--
Kirill A. Shutemov
next prev parent reply other threads:[~2019-05-22 15:22 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-20 14:00 Kirill Tkhai
2019-05-20 14:00 ` [PATCH v2 1/7] mm: Add process_vm_mmap() syscall declaration Kirill Tkhai
2019-05-21 0:28 ` Ira Weiny
2019-05-21 8:29 ` Kirill Tkhai
2019-05-20 14:00 ` [PATCH v2 2/7] mm: Extend copy_vma() Kirill Tkhai
2019-05-21 8:18 ` Kirill A. Shutemov
2019-05-21 8:48 ` Kirill Tkhai
2019-05-20 14:00 ` [PATCH v2 3/7] mm: Extend copy_page_range() Kirill Tkhai
2019-05-20 14:00 ` [PATCH v2 4/7] mm: Export round_hint_to_min() Kirill Tkhai
2019-05-20 14:00 ` [PATCH v2 5/7] mm: Introduce may_mmap_overlapped_region() helper Kirill Tkhai
2019-05-20 14:00 ` [PATCH v2 6/7] mm: Introduce find_vma_filter_flags() helper Kirill Tkhai
2019-05-20 14:00 ` [PATCH v2 7/7] mm: Add process_vm_mmap() Kirill Tkhai
2019-05-21 14:43 ` [PATCH v2 0/7] mm: process_vm_mmap() -- syscall for duplication a process mapping Andy Lutomirski
2019-05-21 15:52 ` Kirill Tkhai
2019-05-21 15:59 ` Kirill Tkhai
2019-05-21 16:20 ` Jann Horn
2019-05-21 17:03 ` Kirill Tkhai
2019-05-21 17:28 ` Jann Horn
2019-05-22 10:03 ` Kirill Tkhai
2019-05-21 16:43 ` Andy Lutomirski
2019-05-21 17:44 ` Kirill Tkhai
2019-05-23 16:19 ` Andy Lutomirski
2019-05-24 10:36 ` Kirill Tkhai
2019-05-22 15:22 ` Kirill A. Shutemov [this message]
2019-05-23 16:11 ` Kirill Tkhai
2019-05-24 10:45 ` Kirill Tkhai
2019-05-24 11:52 ` Kirill A. Shutemov
2019-05-24 14:00 ` Kirill Tkhai
2019-05-27 23:30 ` Kirill A. Shutemov
2019-05-28 9:15 ` Kirill Tkhai
2019-05-28 16:15 ` Kirill A. Shutemov
2019-05-29 14:33 ` Kirill Tkhai
2019-06-03 14:38 ` Kirill Tkhai
2019-06-03 14:56 ` Kirill Tkhai
2019-06-03 17:47 ` Kirill A. Shutemov
2019-06-04 9:32 ` Kirill Tkhai
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