Re: [kmemleak] b751c52bb5: BUG:kernel_hang_in_boot_stage

[Li Zhijian]

On 6/10/20 6:56 PM, Catalin Marinas wrote:

On Wed, Jun 10, 2020 at 03:51:56PM +0800, kernel test robot wrote:

FYI, we noticed the following commit (built with gcc-7):

commit: b751c52bb587ae66f773b15204ef7a147467f4c7 ("kmemleak: increase 
DEBUG_KMEMLEAK_EARLY_LOG_SIZE default to 16K")
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master

in testcase: boot

on test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -smp 2 -m 8G

[...]

BUG: kernel hang in boot stage

To reproduce:

         # build kernel
        cd linux
        cp config-5.3.0-11789-gb751c52bb587a .config
        make HOSTCC=gcc-7 CC=gcc-7 ARCH=i386 olddefconfig prepare 
modules_prepare bzImage

I've never tried kmemleak on i386.

Anyway, I'm not sure what caused the hang (or whether it's a hang at
all) but I suspect prior to the above commit, kmemleak probably just
disabled itself (early log  buffer exceeded).

So the bug may have been
there already,

I think so

only that kmemleak started working and tripped over it
when the log buffer increased.

Is there a chance that the kernel got much slower with kmemleak enabled
and the test scripts timed out?

Does this problem still exist with the latest mainline?

Yes, that's true.

Thanks
Zhijian (0Day CI team)

Thanks.