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From: Doug Anderson <dianders@chromium.org>
Date: Thu, 1 Feb 2024 19:15:48 -0800
Message-ID: <CAD=FV=Wbq7R9AirvxnW1aWoEnp2fWQrwBsxsDB46xbfTLHCZ4w@mail.gmail.com>
Subject: Re: [PATCH] regset: use vmalloc() for regset_get_alloc()
To: Al Viro <viro@zeniv.linux.org.uk>
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
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Hi,

On Thu, Feb 1, 2024 at 7:04=E2=80=AFPM Al Viro <viro@zeniv.linux.org.uk> wr=
ote:
>
> 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=3Dgpu-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.

Of course! Here are the big ones:

[   45.875574] DOUG: Allocating 279584 bytes, n=3D17474, size=3D16,
core_note_type=3D1029
[   45.884809] DOUG: Allocating 8768 bytes, n=3D548, size=3D16, core_note_t=
ype=3D1035
[   45.893958] DOUG: Allocating 65552 bytes, n=3D4097, size=3D16,
core_note_type=3D1036

-Doug