Re: [Bug 210023] New: Crash when allocating > 2 TB memory

[Andrew Morton <akpm@linux-foundation.org>]

On Wed, 4 Nov 2020 08:55:11 -0500 Hsin-Hui Wu <hsinhuiwu@gmail.com> wrote:

> > With a machine with 3 TB (more than 2 TB memory). If you use vmalloc to
> > allocate > 2 TB memory, the array_size below will be overflowed.
> 
> How was this observed?
> 
> Is there any know userspace operation which causes the kernel to try to
> vmalloc such a large hunk of memory?
> 
> [Frank] The Dell PowerEdge R740/R940 can have up to  3TB/6TB memory.
> installed. Our application requires reserve consecutive memory in the kernel
> space and protected from userspace programs.

Did this require custom kernel changes?  If not, precisely which system
calls were used to cause this allocation attempt?

> ----------------------------------------------------------------------------------------------------
> OK, thanks.  Against current mainline your proposed change would look
> like this, yes?
> 
> [Frank] Yes. This will support up to less than 16 TB. If you want to support
>  more than 16 TB, we need to expand nr_pages to unsigned long as
> Matthew pointed out.
> 
> Will it be possible to add this to kernel 3.10.0-957.27.2.el7.x86_64?

That is up to Red Hat to decide.