From: Al Viro <viro@ZenIV.linux.org.uk>
To: Jens Axboe <axboe@kernel.dk>
Cc: linux-fsdevel@vger.kernel.org,
Nicholas Piggin <npiggin@gmail.com>,
Miklos Szeredi <mszeredi@redhat.com>
Subject: [RFC] vmsplice() and ->steal()
Date: Sat, 10 Dec 2016 02:38:49 +0000 [thread overview]
Message-ID: <20161210023849.GH1555@ZenIV.linux.org.uk> (raw)
vmsplice() generates pipe_bufs with ->steal() set to
user_page_pipe_buf_steal(). What should happen when the source pages
had code from an mmapped area and why shouldn't their ->steal()
do what page_cache_pipe_buf_release() does in that case?
As it is, e.g. fuse_dev_splice_write() getting fed that stuff could,
AFAICS, clear MappedToDisk on such a page, scream about weird pages
(upon noticing non-NULL ->mapping) and fall back to copying (thankfully).
We don't have that many ->steal() users (as the matter of fact, I've
discovered that while trying to debug the breakage in one I'd been
trying to add), but I really wonder about the intended semantics of
->steal().
Comments?
next reply other threads:[~2016-12-10 2:38 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-10 2:38 Al Viro [this message]
2016-12-10 3:03 ` [RFC] vmsplice() and ->steal() Al Viro
2016-12-10 5:28 ` Nicholas Piggin
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20161210023849.GH1555@ZenIV.linux.org.uk \
--to=viro@zeniv.linux.org.uk \
--cc=axboe@kernel.dk \
--cc=linux-fsdevel@vger.kernel.org \
--cc=mszeredi@redhat.com \
--cc=npiggin@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.