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SubjectRe: init_on_free breaks hibernate
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On Monday, January 13, 2020 10:26:04 AM CET Johannes Stezenbach wrote:
> Hi,
>
> On Mon, Dec 23, 2019 at 10:13:09PM +0100, Johannes Stezenbach wrote:
> > I upgraded the kernel on one of my machines to 5.3.18 (from 5.2.x)
> > and found it failed after resume from hibernate due to what seemed
> > to be memory corruption. I had a hunch it could be related to
> > CONFIG_INIT_ON_ALLOC_DEFAULT_ON or CONFIG_INIT_ON_FREE_DEFAULT_ON,
> > and a quick web search found this which seems to confirm:
> > https://bbs.archlinux.org/viewtopic.php?pid=1877845#p1877845
> >
> > I rebuilt the kernel with CONFIG_INIT_ON_FREE_DEFAULT_ON disabled,
> > and hibernate works again. I'm fine with this workaround and
> > just wanted to share this information.
> >
> > The commit that introduces CONFIG_INIT_ON_FREE_DEFAULT_ON:
> > 6471384af2a6 mm: security: introduce init_on_alloc=1 and init_on_free=1 boot options
>
> I tested 5.4.11 and current git master (b07f636fca1c8)
> in Qemu and was able to reproduce the issue in both.

Let's add more people and the LKML to the CC.

Alex, Kees, Michal, any comments?

> Basically I followed the description here
> http://ncmiller.github.io/2016/05/14/linux-and-qemu.html
> to build a minimal image using busybox (I'm using
> the binary from Debian's busybox-static package),
> then added s swap image (-drive file=disk.img,if=virtio),
> do "mkswap /dev/vda" the first time.
>
> hibernate: swapon /dev/vda; echo disk >/sys/power/state
> resume: echo 254:0 >/sys/power/resume
>
> Since busybox is very light on memory usage it doesn't
> trigger immediately, but these commands seem to do it
> reliably:
>
> dmesg | gzip >/dev/null
> find /sys | bzip2 | sha512sum
>
>
> my initramfs:
> 6012997 4 drwxr-xr-x 4 js js 4096 Jan 8 21:25 initramfs
> 6022584 4 drwxr-xr-x 2 js js 4096 Jan 8 21:21 initramfs/dev
> 5909013 4 -rwxr-xr-x 1 js js 514 Jan 8 21:25 initramfs/init
> 6012998 4 drwxr-xr-x 2 js js 4096 Jan 8 20:41 initramfs/bin
> 5909011 1904 -rwxr-xr-x 1 js js 1945856 Apr 1 2019 initramfs/bin/busybox
> 5909012 0 lrwxrwxrwx 1 js js 7 Feb 14 2018 initramfs/bin/sh -> busybox
>
> my /init:
> #!/bin/sh
>
> PATH=/bin
> export PATH
>
> # Create dirs
> /bin/busybox mkdir -p /proc /sys /etc /tmp /usr
> /bin/busybox ln -s /bin /sbin
> /bin/busybox ln -s /bin /usr/bin
> /bin/busybox ln -s /bin /usr/sbin
> # Create all the symlinks to busybox
> /bin/busybox --install -s
>
> mount -t proc proc /proc
> mount -t sysfs sysfs /sys
> mount -t devtmpfs devtmpfs /dev
>
> echo -e "\nBoot took $(cut -d' ' -f1 /proc/uptime) seconds\n"
>
> # shell where ^C works
> setsid busybox cttyhack sh
> # avoid "PID 1 exited" oops
> poweroff -f
> ---------
>
>
> qemu-system-x86_64 -m 128 -enable-kvm \
> -kernel ../linux/arch/x86/boot/bzImage \
> -initrd initramfs.cpio \
> -drive file=disk.img,if=virtio \
> -nographic -append "console=ttyS0 init_on_alloc=1 init_on_free=1"
>
>
> Johannes
>




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