On Tue, Apr 16, 2019 at 4:44 PM Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote: > > On Tue, 16 Apr 2019 13:54:04 -0700 Dan Williams <dan.j.williams@xxxxxxxxx> wrote: > > > When a module option, or core kernel argument, toggles a static-key it > > requires jump labels to be initialized early. While x86, PowerPC, and > > ARM64 arrange for jump_label_init() to be called before parse_args(), > > ARM does not. > > > > Kernel command line: rdinit=/sbin/init page_alloc.shuffle=1 panic=-1 console=ttyAMA0,115200 page_alloc.shuffle=1 > > ------------[ cut here ]------------ > > WARNING: CPU: 0 PID: 0 at ./include/linux/jump_label.h:303 > > page_alloc_shuffle+0x12c/0x1ac > > static_key_enable(): static key 'page_alloc_shuffle_key+0x0/0x4' used > > before call to jump_label_init() > > Modules linked in: > > CPU: 0 PID: 0 Comm: swapper Not tainted > > 5.1.0-rc4-next-20190410-00003-g3367c36ce744 #1 > > Hardware name: ARM Integrator/CP (Device Tree) > > [<c0011c68>] (unwind_backtrace) from [<c000ec48>] (show_stack+0x10/0x18) > > [<c000ec48>] (show_stack) from [<c07e9710>] (dump_stack+0x18/0x24) > > [<c07e9710>] (dump_stack) from [<c001bb1c>] (__warn+0xe0/0x108) > > [<c001bb1c>] (__warn) from [<c001bb88>] (warn_slowpath_fmt+0x44/0x6c) > > [<c001bb88>] (warn_slowpath_fmt) from [<c0b0c4a8>] > > (page_alloc_shuffle+0x12c/0x1ac) > > [<c0b0c4a8>] (page_alloc_shuffle) from [<c0b0c550>] (shuffle_store+0x28/0x48) > > [<c0b0c550>] (shuffle_store) from [<c003e6a0>] (parse_args+0x1f4/0x350) > > [<c003e6a0>] (parse_args) from [<c0ac3c00>] (start_kernel+0x1c0/0x488) > > > > Move the fallback call to jump_label_init() to occur before > > parse_args(). The redundant calls to jump_label_init() in other archs > > are left intact in case they have static key toggling use cases that are > > even earlier than option parsing. > > Has it been confirmed that this fixes > mm-shuffle-initial-free-memory-to-improve-memory-side-cache-utilization.patch > on beaglebone-black? This only fixes dynamically enabling the shuffling on 32-bit ARM. Guenter happened to run without the mm-only 'force-enable-always' patch and when he went to use the command line option to enable it he hit the jump-label warning. The original beaglebone-black failure was something different and avoided this case because the jump-label was never used. I am otherwise unable to recreate the failure on either the original failing -next, nor on v5.1-rc5 plus the latest state of the patches. I need from someone who is actually still seeing the failure so they can compare with the configuration that is working for me. For reference that's the Yocto beaglebone-black defconfig: https://github.com/jumpnow/meta-bbb/blob/thud/recipes-kernel/linux/linux-stable-5.0/beaglebone/defconfig
