linux-kernel - Re: Linux 2.6.38-rc5

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Message-ID: <AANLkTimnLPF0wz+ya-Wj1U1hQjPJpUhmL893OxBWqZYM@mail.gmail.com>
Date:	Wed, 16 Feb 2011 07:46:20 -0800
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Al Viro <viro@...iv.linux.org.uk>
Subject: Re: Linux 2.6.38-rc5

On Wed, Feb 16, 2011 at 3:14 AM, Eric Dumazet <eric.dumazet@...il.com> wrote:
>
> Using this kernel on my dev machine (2x4x2 cpus), I hit BUG_ON() in
> fs/namei.c:1461 on my kernel build (make -j16)

Uhhuh. We replaced one BUG_ON() with another.

And I think it's a really silly problem too: when Al moved the

        /* We drop rcu-walk here */
        if (nameidata_dentry_drop_rcu_maybe(nd, path->dentry))
                return -ECHILD;

test into do_follow_link(), he _should_ have moved the BUG_ON() in
there too, methinks. He didn't, and as a result the BUG_ON() is now
before the "drop_rcu_maybe".

This patch should fix it. Al? Comments?

(Of course, we could just remove the BUG_ON() entirely, but
considering that this is still fragile new code I'd rather leave it
in)

                               Linus

View attachment "patch.diff" of type "text/x-patch" (1554 bytes)