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SubjectRe: [init/initramfs.c] e7cb072eb9: invoked_oom-killer:gfp_mask=0x
From
Date
On 07/06/2021 16.44, kernel test robot wrote:
>
>
> Greeting,
>
> FYI, we noticed the following commit (built with gcc-9):
>
> commit: e7cb072eb988e46295512617c39d004f9e1c26f8 ("init/initramfs.c: do unpacking asynchronously")
> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master
>
>
> in testcase: locktorture
> version:
> with following parameters:
>
> runtime: 300s
> test: cpuhotplug
>
> test-description: This torture test consists of creating a number of kernel threads which acquire the lock and hold it for specific amount of time, thus simulating different critical region behaviors.
> test-url: https://www.kernel.org/doc/Documentation/locking/locktorture.txt
>
>
> on test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -smp 2 -m 16G
>
> caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace):
>
>
> please be noted that we use 'vmalloc=512M' for both parent and this commit.
> since it's ok on parent but oom on this commit, we want to send this report
> to show the potential problem of the commit on some cases.
>
> we also tested by changing to use 'vmalloc=128M', it will succeed.
>
>
> If you fix the issue, kindly add following tag
> Reported-by: kernel test robot <oliver.sang@intel.com>
>
>
> [ 4.443950] e1000: Copyright (c) 1999-2006 Intel Corporation.
> [ 4.716374] ACPI: _SB_.LNKC: Enabled at IRQ 11
> [ 5.081518] e1000 0000:00:03.0 eth0: (PCI:33MHz:32-bit) 52:54:00:12:34:56
> [ 5.082999] e1000 0000:00:03.0 eth0: Intel(R) PRO/1000 Network Connection
> [ 5.085275] VFIO - User Level meta-driver version: 0.3
> [ 8.029204] kworker/u4:0 invoked oom-killer: gfp_mask=0x100cc0(GFP_USER), order=0, oom_score_adj=0
> [ 8.031021] CPU: 1 PID: 7 Comm: kworker/u4:0 Not tainted 5.12.0-11533-ge7cb072eb988 #1
> [ 8.031988] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014
> [ 8.031988] Workqueue: events_unbound async_run_entry_fn
> [ 8.031988] Call Trace:
> [ 8.031988] dump_stack (kbuild/src/consumer/lib/dump_stack.c:122)
> [ 8.031988] dump_header (kbuild/src/consumer/mm/oom_kill.c:463)
> [ 8.031988] ? lock_release (kbuild/src/consumer/kernel/locking/lockdep.c:5190 kbuild/src/consumer/kernel/locking/lockdep.c:5532)
> [ 8.031988] ? out_of_memory (kbuild/src/consumer/include/linux/rcupdate.h:710 kbuild/src/consumer/mm/oom_kill.c:379 kbuild/src/consumer/mm/oom_kill.c:1102 kbuild/src/consumer/mm/oom_kill.c:1048)
> [ 8.031988] out_of_memory.cold (kbuild/src/consumer/mm/oom_kill.c:1106 kbuild/src/consumer/mm/oom_kill.c:1048)
>
>
> To reproduce:
>
> # build kernel
> cd linux
> cp config-5.12.0-11533-ge7cb072eb988 .config
> make HOSTCC=gcc-9 CC=gcc-9 ARCH=i386 olddefconfig prepare modules_prepare bzImage modules
> make HOSTCC=gcc-9 CC=gcc-9 ARCH=i386 INSTALL_MOD_PATH=<mod-install-dir> modules_install
> cd <mod-install-dir>
> find lib/ | cpio -o -H newc --quiet | gzip > modules.cgz

So I got this far...

> git clone https://github.com/intel/lkp-tests.git
> cd lkp-tests
> bin/lkp qemu -k <bzImage> -m modules.cgz job-script # job-script is attached in this email

Is there some way to reproduce which doesn't require adding an lkp user?
Also, I don't have 16G to give to a virtual machine. I tried running the
bzImage with that modules.cgz under qemu with some naive parameters just
to get some output [1], but other than failing because there's no rootfs
to mount (as expected), I only managed to make it fail when providing
too little memory (the .cgz is around 70M, decompressed about 200M -
giving '-m 1G' to qemu works fine). You mention the vmalloc= argument,
but I can't make the decompression fail when passing either vmalloc=128M
or vmalloc=512M or no vmalloc= at all.

As an extra data point, what happens if you add initramfs_async=0 to the
command line?

[1] qemu-system-x86_64 -kernel arch/i386/boot/bzImage -initrd
../../tmp/header-install/modules.cgz -append "console=ttyAMA0
console=ttyS0 vmalloc=512M" -serial stdio -smp 2 -m 1G

Rasmus

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