FYI, we noticed the following commit: commit: b6081675fb4527cabf74dfdda89d49968f65f3e7 ("XArray: Convert IDR and add test suite") git://git.infradead.org/users/willy/linux-dax.git xarray-2017-03-11 in testcase: boot on test machine: qemu-system-x86_64 -enable-kvm -m 420M caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace): +------------------------------------------------+------------+------------+ | | d37abd2a01 | b6081675fb | +------------------------------------------------+------------+------------+ | boot_successes | 6 | 0 | | boot_failures | 0 | 6 | | WARNING:at_mm/slab_common.c:#kmem_cache_create | 0 | 6 | | INFO:trying_to_register_non-static_key | 0 | 6 | +------------------------------------------------+------------+------------+ [ 0.004000] WARNING: CPU: 0 PID: 0 at mm/slab_common.c:103 kmem_cache_create+0xda/0x24c [ 0.004000] Modules linked in: [ 0.004000] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.11.0-rc2-00005-gb608167 #225 [ 0.004000] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.9.3-20161025_171302-gandalf 04/01/2014 [ 0.004000] Call Trace: [ 0.004000] dump_stack+0x82/0xb8 [ 0.004000] __warn+0xc2/0xdd [ 0.004000] warn_slowpath_null+0x1d/0x1f [ 0.004000] kmem_cache_create+0xda/0x24c [ 0.004000] ? tag_get+0x13/0x13 [ 0.004000] xarray_init+0x23/0x2c [ 0.004000] start_kernel+0x23a/0x43d [ 0.004000] ? early_idt_handler_array+0x120/0x120 [ 0.004000] x86_64_start_reservations+0x2a/0x2c [ 0.004000] x86_64_start_kernel+0x133/0x142 [ 0.004000] start_cpu+0x14/0x14 [ 0.004000] ---[ end trace 0000000000000000 ]--- To reproduce: git clone https://github.com/01org/lkp-tests.git cd lkp-tests bin/lkp qemu -k <bzImage> job-script # job-script is attached in this email Thanks, Kernel Test Robot