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.