From: Linus Torvalds <torvalds@linux-foundation.org>
To: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Linux-MM <linux-mm@kvack.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Yu Zhao <yuzhao@google.com>, Andy Lutomirski <luto@kernel.org>,
Peter Xu <peterx@redhat.com>, Pavel Emelyanov <xemul@openvz.org>,
Mike Kravetz <mike.kravetz@oracle.com>,
Mike Rapoport <rppt@linux.vnet.ibm.com>,
Minchan Kim <minchan@kernel.org>, Will Deacon <will@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Hugh Dickins <hughd@google.com>,
"Kirill A. Shutemov" <kirill@shutemov.name>,
Matthew Wilcox <willy@infradead.org>,
Oleg Nesterov <oleg@redhat.com>, Jann Horn <jannh@google.com>,
Kees Cook <keescook@chromium.org>,
John Hubbard <jhubbard@nvidia.com>,
Leon Romanovsky <leonro@nvidia.com>,
Jason Gunthorpe <jgg@ziepe.ca>, Jan Kara <jack@suse.cz>,
Kirill Tkhai <ktkhai@virtuozzo.com>,
Nadav Amit <nadav.amit@gmail.com>, Jens Axboe <axboe@kernel.dk>
Subject: Re: [PATCH 0/1] mm: restore full accuracy in COW page reuse
Date: Sat, 9 Jan 2021 17:37:09 -0800 [thread overview]
Message-ID: <CAHk-=wg3zWaXaKN1N=qTWiuLFvEz3e_d5oZSgOEfbSOrXJvVtQ@mail.gmail.com> (raw)
In-Reply-To: <CAHk-=wj5=1DKbQut1-21EwQbMSghNL3KOSd82rNrBhuG9+eekA@mail.gmail.com>
On Sat, Jan 9, 2021 at 5:19 PM Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> And no, I didn't make the UFFDIO_WRITEPROTECT code take the mmap_sem
> for writing. For whoever wants to look at that, it's
> mwriteprotect_range() in mm/userfaultfd.c and the fix is literally to
> turn the read-lock (and unlock) into a write-lock (and unlock).
Oh, and if it wasn't obvious, we'll have to debate what to do with
trying to mprotect() a pinned page. Do we just ignore the pinned page
(the way my clear_refs patch did)? Or do we turn it into -EBUSY? Or
what?
So it's not *just* the locking that needs to be fixed. But just take a
look at that suggested clear_refs patch of mine - it sure isn't
complicated.
Linus
next prev parent reply other threads:[~2021-01-10 1:37 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-10 0:44 Andrea Arcangeli
2021-01-10 0:44 ` [PATCH 1/1] " Andrea Arcangeli
2021-01-10 2:54 ` Andrea Arcangeli
2021-01-11 14:11 ` Kirill A. Shutemov
2021-01-10 0:55 ` [PATCH 0/1] " Linus Torvalds
2021-01-10 1:19 ` Linus Torvalds
2021-01-10 1:37 ` Linus Torvalds [this message]
2021-01-10 3:24 ` Andrea Arcangeli
2021-01-10 2:51 ` Andrea Arcangeli
2021-01-10 3:51 ` Linus Torvalds
2021-01-10 19:30 ` Linus Torvalds
2021-01-11 1:18 ` Jason Gunthorpe
2021-01-11 7:26 ` John Hubbard
2021-01-11 12:42 ` Matthew Wilcox
2021-01-11 16:05 ` Jason Gunthorpe
2021-01-11 16:15 ` Michal Hocko
2021-01-11 19:19 ` Linus Torvalds
2021-01-11 22:18 ` Linus Torvalds
2021-01-12 17:07 ` Andy Lutomirski
2021-01-12 23:51 ` Jerome Glisse
2021-01-13 2:16 ` Matthew Wilcox
2021-01-13 2:43 ` Linus Torvalds
2021-01-13 3:31 ` Linus Torvalds
2021-01-13 8:52 ` David Hildenbrand
2021-01-13 8:57 ` David Hildenbrand
2021-01-13 12:32 ` Kirill A. Shutemov
2021-01-13 12:55 ` Matthew Wilcox
2021-01-13 19:54 ` Linus Torvalds
2021-01-13 23:54 ` Peter Xu
2021-01-11 15:52 ` Jason Gunthorpe
2021-01-15 8:59 ` David Hildenbrand
2021-01-15 18:37 ` Jason Gunthorpe
2021-01-15 19:46 ` David Hildenbrand
2021-01-15 19:53 ` Jason Gunthorpe
2021-01-16 3:40 ` John Hubbard
2021-01-16 11:42 ` David Hildenbrand
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