From: David Laight <David.Laight@ACULAB.COM>
To: 'Pavel Begunkov' <asml.silence@gmail.com>,
Jens Axboe <axboe@kernel.dk>,
"io-uring@vger.kernel.org" <io-uring@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH] io_uring: fix iovec leaks
Date: Tue, 11 Feb 2020 11:16:40 +0000 [thread overview]
Message-ID: <0d61cafdb0b040ac8bb3542b6022d0fc@AcuMS.aculab.com> (raw)
In-Reply-To: <045f6c04-a6d8-146c-75f3-2c0d65e482d6@gmail.com>
From: Pavel Begunkov
> Sent: 11 February 2020 11:05
> On 2/11/2020 1:07 PM, David Laight wrote:
> > From: Pavel Begunkov
> >> Sent: 07 February 2020 19:05
> >> Allocated iovec is freed only in io_{read,write,send,recv)(), and just
> >> leaves it if an error occured. There are plenty of such cases:
> >> - cancellation of non-head requests
> >> - fail grabbing files in __io_queue_sqe()
> >> - set REQ_F_NOWAIT and returning in __io_queue_sqe()
> >> - etc.
> >>
> >> Add REQ_F_NEED_CLEANUP, which will force such requests with custom
> >> allocated resourses go through cleanup handlers on put.
> >
> > This looks horribly fragile.
>
> Well, not as horrible as it may appear -- set the flag, whenever you
> want the corresponding destructor to be called, and clear it when is not
> needed anymore.
>
> I'd love to have something better, maybe even something more intrusive
> for-next, but that shouldn't hurt the hot path. Any ideas?
Given all the 'cud chewing' that happens in code paths
like the one that read iov from userspace just adding:
if (unlikely(foo->ptr))
kfree(foo->ptr);
before 'foo' goes out of scope (or is reused) is probably
not measurable.
David
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
next prev parent reply other threads:[~2020-02-11 11:16 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-07 19:04 [PATCH] io_uring: fix iovec leaks Pavel Begunkov
2020-02-07 19:09 ` Pavel Begunkov
2020-02-07 20:40 ` Jens Axboe
2020-02-11 10:07 ` David Laight
2020-02-11 11:05 ` Pavel Begunkov
2020-02-11 11:16 ` David Laight [this message]
2020-02-11 11:43 ` Pavel Begunkov
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=0d61cafdb0b040ac8bb3542b6022d0fc@AcuMS.aculab.com \
--to=david.laight@aculab.com \
--cc=asml.silence@gmail.com \
--cc=axboe@kernel.dk \
--cc=io-uring@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
/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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).