On Mon, 2021-05-10 at 13:19 +0100, Matthew Wilcox wrote: > On Mon, May 10, 2021 at 11:12:21AM +0000, Rantala, Tommi T. (Nokia - > FI/Espoo) wrote: > > 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. Ahh, thanks! Indeed I missed "proc: use kvzalloc for our kernel buffer" -Tommi
