Re: cat /proc/sys/kernel/tainted => page allocation failure: order:6

[Matthew Wilcox]

On Mon, May 10, 2021 at 11:12:21AM +0000, Rantala, Tommi T. (Nokia - FI/Espoo) wrote:
> Hello,
> 
> Why is order 6 allocation required for "cat /proc/sys/kernel/tainted" ...?
> I'm seeing (occasional) failures in one VM (with 65d uptime):
> 
> [5674989.634561] cat: page allocation failure: order:6, mode:0x40dc0(GFP_KERNEL|__GFP_COMP|__GFP_ZERO), nodemask=(null),cpuset=user.slice,mems_allowed=0
> [5674989.645432] CPU: 0 PID: 2717524 Comm: cat Not tainted 5.10.19-200.fc33.x86_64 #1

The underlying problem is that 'cat' is asking to do a 128kB read (!)
so we allocate 256kB (!) of contiguous (!) memory.  This is already
mostly fixed upstream.  Please upgrade your kernel.