On Tue, 31 Jan 2023 at 16:07, Will Deacon <will@xxxxxxxxxx> wrote: > > Now really adding Ard... > > On Tue, Jan 31, 2023 at 03:06:44PM +0000, Will Deacon wrote: > > +Ard -- full thread here: > > > > https://lore.kernel.org/all/20221227092634.445212-1-liushixin2@xxxxxxxxxx/ > > > > On Sun, Jan 29, 2023 at 01:41:47PM -0800, Andrew Morton wrote: > > > On Sun, 29 Jan 2023 10:44:31 +0800 Liu Shixin <liushixin2@xxxxxxxxxx> wrote: > > > > > > > Hi, > > > > > > > > > > > > This patch seems to have been lost in the corner. Recently I've meet this problem again > > > > > > > > on v6.1, so I would like to propose this patch again. > > > > > > > > > > > > Thanks, > > > > > > > > > > > > On 2022/12/27 17:26, Liu Shixin wrote: > > > > > After I add a 10GB pmem device, I got the following error message when > > > > > insert module: > > > > > > > > > > insmod: vmalloc error: size 16384, vm_struct allocation failed, > > > > > mode:0xcc0(GFP_KERNEL), nodemask=(null),cpuset=/,mems_allowed=0 > > > > > > > > > > If CONFIG_RANDOMIZE_BASE is set, the module region can be located in the > > > > > vmalloc region entirely. Although module_alloc() can fall back to a 2GB > > > > > window if ARM64_MODULE_PLTS is set, the module region is still easily > > > > > exhausted because the module region is located at bottom of vmalloc region > > > > > and the vmalloc region is allocated from bottom to top. > > > > > > > > > > Skip module region if not calling from module_alloc(). > > > > > > > > > > > I'll assume this is for the arm tree. > > > > > > Acked-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > > > > This looks like the same issue previously reported at: > > > > https://lore.kernel.org/all/e6a804de-a5f7-c551-ffba-e09d04e438fc@xxxxxxxxxxxxx/ > > > > where Ard had a few suggestions but, afaict, they didn't help. > > Thanks for the cc. So this is a bit clunky, and I wonder whether we wouldn't be better off just splitting the vmalloc region into two separate regions: one for the kernel and modules, and one for everything else. That way, we lose one bit of entropy in the randomized placement, but the default 48-bit VA space is vast anway, and even on 39-bit VA configs (such as Android), I seriously doubt that we come anywhere close to exhausting the vmalloc space today.
