From: Nick Piggin <npiggin@kernel.dk>
To: Christoph Hellwig <hch@lst.de>
Cc: Nick Piggin <npiggin@kernel.dk>,
Linus Torvalds <torvalds@linux-foundation.org>,
Al Viro <viro@ZenIV.linux.org.uk>,
linux-fsdevel@vger.kernel.org
Subject: Re: Patch "fs: use RCU read side protection in d_validate" broken
Date: Tue, 16 Nov 2010 09:51:08 +1100 [thread overview]
Message-ID: <20101115225108.GA3540@amd> (raw)
In-Reply-To: <20101115210906.GA5964@lst.de>
On Mon, Nov 15, 2010 at 10:09:06PM +0100, Christoph Hellwig wrote:
> On Mon, Nov 15, 2010 at 04:11:20PM +1100, Nick Piggin wrote:
> > This patch is totally broken. You can't just dget() a dentry with
> > nothing but RCU critical section open.
>
> The plain dget is indeed wrong as we should at least take d_lock
> and check d_count for zero before incrementing it to protect
> against shrink_dentry_list.
>
> I'm not quite sure it really matters as d_validate already has
Explain why it doesn't matter. It's an oopsable bug introduced.
> and always ad much worse bugs, such as the complete lack of
> protection against renames.
What are the much worse bugs? What do you mean by rename protection?
> Anyway, I'll send a patch to Linus to fix this issue for now.
A revert is appropriate. Like I said, there is no need for this patch at
all and no justification provided.
prev parent reply other threads:[~2010-11-15 22:51 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-11-15 5:11 Patch "fs: use RCU read side protection in d_validate" broken Nick Piggin
2010-11-15 5:32 ` Nick Piggin
2010-11-15 21:16 ` Christoph Hellwig
2010-11-15 23:06 ` Nick Piggin
2010-11-15 21:09 ` Christoph Hellwig
2010-11-15 22:51 ` Nick Piggin [this message]
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=20101115225108.GA3540@amd \
--to=npiggin@kernel.dk \
--cc=hch@lst.de \
--cc=linux-fsdevel@vger.kernel.org \
--cc=torvalds@linux-foundation.org \
--cc=viro@ZenIV.linux.org.uk \
/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.