Re: [PATCH] regset: use vmalloc() for regset_get_alloc()

From: Al Viro <viro@zeniv.linux.org.uk>
To: Doug Anderson <dianders@chromium.org>
Cc: Christian Brauner <brauner@kernel.org>,
	Eric Biederman <ebiederm@xmission.com>, Jan Kara <jack@suse.cz>,
	Kees Cook <keescook@chromium.org>,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org
Subject: Re: [PATCH] regset: use vmalloc() for regset_get_alloc()
Date: Fri, 2 Feb 2024 03:04:38 +0000	[thread overview]
Message-ID: <20240202030438.GV2087318@ZenIV> (raw)
In-Reply-To: <CAD=FV=X5dpMyCGg4Xn+ApRwmiLB5zB0LTMCoSfW_X6eAsfQy8w@mail.gmail.com>

On Thu, Feb 01, 2024 at 06:54:51PM -0800, Doug Anderson wrote:
> >         What the hell?  Which regset could have lead to that?
> > It would need to have the total size of register in excess of
> > 256K.  Seriously, which regset is that about?  Note that we
> > have just made sure that size is not greater than that product.
> > size is unsigned int, so it's not as if a negative value passed
> > to function could get through that test only to be interpreted
> > as large positive later...
> >
> >         Details, please.
> 
> I can continue to dig more, but it is easy for me to reproduce this.
> On the stack is elf_core_dump() and it seems like we're getting a core
> dump of the chrome process. So I just arbitrarily look for the chrome
> GPU process:
> 
> $ ps aux | grep gpu-process
> chronos   2075  3.0  1.1 34075552 95372 ?      S<l  18:44   0:01
> /opt/google/chrome/chrome --type=gpu-process ...
> 
> Then I send it a quit:
> 
> $ kill -quit 2075
> 
> I added some printouts for this allocation and there are a ton. Here's
> all of them, some of which are over 256K:

Well, the next step would be to see which regset it is - if you
see that kind of allocation, print regset->n, regset->size and
regset->core_note_type.