linux-kernel - Re: 3.6rc6 slab corruption.

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Message-ID: <CA+55aFzU1S6cybghVv4Bg2K8X1NC2pX2XebSrEgn0pKtgyCfRw@mail.gmail.com>
Date:	Wed, 19 Sep 2012 16:01:50 -0700
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	David Rientjes <rientjes@...gle.com>
Cc:	Konrad Rzeszutek Wilk <konrad@...nel.org>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	Dave Jones <davej@...hat.com>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Srivatsa Vaddagiri <vatsa@...ux.vnet.ibm.com>,
	Suzuki Poulose <suzuki@...ibm.com>,
	Raghavendra K T <raghavendra.kt@...ux.vnet.ibm.com>
Subject: Re: 3.6rc6 slab corruption.

On Wed, Sep 19, 2012 at 2:49 PM, David Rientjes <rientjes@...gle.com> wrote:
>
> An alternative to this, though, might be to never test for *ppos == 0 in
> u32_array_read() and do the format_array_alloc() in u32_array_open() to
> initialize file->private_data.  If that allocation fails, just return
> -ENOMEM.  Then you never need to add a mutex in the read path.
>
> Any reason we can't do this?

That does look simpler, and avoiding the lock is a good idea. Since we
don't support lseek() (or pread/pwrite) on that thing anyway, there's
no way to keep the fd open and just re-use it to read the data over
and over, so populating it at open time sounds like a good solution
with no real downsides.

               Linus
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