From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Hugh Dickins <hughd@google.com>,
Matthew Wilcox <willy@infradead.org>,
Linux-MM <linux-mm@kvack.org>,
Andrew Morton <akpm@linux-foundation.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Amir Goldstein <amir73il@gmail.com>
Subject: Re: [PATCH 0/4] Some more lock_page work..
Date: Wed, 14 Oct 2020 16:05:55 +0300 [thread overview]
Message-ID: <20201014130555.kdbxyavqoyfnpos3@box> (raw)
In-Reply-To: <CAHk-=wicH=FaLOeum9_f7Vyyz9Fe4MWmELT7WKR_UbfY37yX-Q@mail.gmail.com>
On Tue, Oct 13, 2020 at 01:03:30PM -0700, Linus Torvalds wrote:
> On Tue, Oct 13, 2020 at 12:59 PM Linus Torvalds
> <torvalds@linux-foundation.org> wrote:
> >
> > Comments?
So we remove strict serialization against truncation in
filemap_map_pages() if the mapping is private.
IIUC, we can end up with a page with ->mapping == NULL set up in a PTE for
such mappings. The "page->mapping != mapping" check makes the race window
smaller, but doesn't remove it.
I'm not sure all codepaths are fine with this. For instance, looks like
migration will back off such pages: __unmap_and_move() doesn't know how to
deal with mapped pages with ->mapping == NULL.
Yes, it is not crash, but still...
Do I miss something?
--
Kirill A. Shutemov
next prev parent reply other threads:[~2020-10-14 13:05 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-13 19:59 [PATCH 0/4] Some more lock_page work Linus Torvalds
2020-10-13 20:03 ` Linus Torvalds
2020-10-14 13:05 ` Kirill A. Shutemov [this message]
2020-10-14 16:53 ` Linus Torvalds
2020-10-14 18:15 ` Matthew Wilcox
2020-10-15 10:41 ` Kirill A. Shutemov
2020-10-15 9:43 ` Kirill A. Shutemov
2020-10-15 16:44 ` Linus Torvalds
2020-10-14 5:50 ` Hugh Dickins
[not found] ` <4794a3fa3742a5e84fb0f934944204b55730829b.camel@lca.pw>
2020-10-15 2:44 ` Linus Torvalds
2020-10-15 15:16 ` Possible deadlock in fuse write path (Was: Re: [PATCH 0/4] Some more lock_page work..) Vivek Goyal
2020-10-15 19:55 ` Vivek Goyal
2020-10-15 21:21 ` Linus Torvalds
2020-10-16 10:02 ` Miklos Szeredi
2020-10-16 12:27 ` Matthew Wilcox
2020-10-20 20:42 ` Vivek Goyal
2020-10-21 7:40 ` Miklos Szeredi
2020-10-21 20:12 ` Vivek Goyal
2020-10-28 20:29 ` Miklos Szeredi
2021-02-09 10:01 ` Miklos Szeredi
2021-02-09 19:09 ` Vivek Goyal
2020-10-16 18:19 ` Vivek Goyal
2020-10-16 18:24 ` Linus Torvalds
2020-10-16 18:24 ` Linus Torvalds
2020-10-16 23:03 ` Dave Chinner
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