[PATCH] Revert "kbuild: create deterministic initramfs directory listings"

[PATCH] Revert "kbuild: create deterministic initramfs directory listings"

[Andrzej Pietrasiewicz]

This reverts commit 9e6e0d5f2a2713402cf9dce69b9f9b516e4185d2.

The reverted commit introduces broken builds. Even though the cpio archive
does contain all the specified files, it seems that the kernel, while
populating rootfs, scans the cpio buffer linearly and fails to create
files whose parent directories are nonexistent at the moment of this failed
creation. As a result, such files are not accessible when kernel boots into
initramfs.

Here is how to reproduce, from inside kernel source directory, with the
patch in question not reverted:

$ mkdir -p ../test/find/me/if/you/can
$ touch ../test/find/me/if/you/can/file.txt
$ cat ../initramfs.list
file /busybox-x86_64 ../initramfs/busybox-x86_64 0755 0 0
dir /sbin 0755 0 0
dir /proc 0755 0 0
dir /sys 0755 0 0
dir /bin 0755 0 0
dir /usr 0755 0 0
dir /usr/sbin 0755 0 0
dir /usr/bin 0755 0 0
dir /etc 0755 0 0
dir /etc/init.d 0755 0 0
file /etc/inittab ../initramfs/inittab 0755 0 0
file /etc/init.d/rcS ../initramfs/rcS-x86_64 0755 0 0
dir /lib 0755 0 0
dir /lib/modules 0755 0 0
$ ls ../initramfs
busybox-x86_64  inittab  rcS-x86_64
$ cat ../initramfs/inittab
::sysinit:/etc/init.d/rcS
::askfirst:-/bin/sh
::ctrlaltdel:/sbin/reboot
::shutdown:/sbin/swapoff -a
::shutdown:/sbin/umount -a -r
::restart:/sbin/init
$ cat ../initramfs/rcS-x86_64
#!/busybox-x86_64 sh

/busybox-x86_64 --install

mount -t proc none /proc
mount -t sysfs none /sys

mdev -s
echo /sbin/mdev > /proc/sys/kernel/hotplug
$ scripts/gen_initramfs_list.sh ../test/ ../initramfs.list

#####################
# ../test/
# Last modified: 1534428527.0818855150

file /find/me/if/you/can/file.txt ../test/find/me/if/you/can/file.txt 664 1000 1000
dir /find/me/if/you/can 775 1000 1000
dir /find/me/if/you 775 1000 1000
dir /find/me/if 775 1000 1000
dir /find/me 775 1000 1000
dir /find 775 1000 1000

#####################
# ../initramfs.list
# Last modified: 1534433777.8384497600

file /busybox-x86_64 ../initramfs/busybox-x86_64 0755 0 0
dir /sbin 0755 0 0
dir /proc 0755 0 0
dir /sys 0755 0 0
dir /bin 0755 0 0
dir /usr 0755 0 0
dir /usr/sbin 0755 0 0
dir /usr/bin 0755 0 0
dir /etc 0755 0 0
dir /etc/init.d 0755 0 0
file /etc/inittab ../initramfs/inittab 0755 0 0
file /etc/init.d/rcS ../initramfs/rcS-x86_64 0755 0 0
dir /lib 0755 0 0
dir /lib/modules 0755 0 0

$ cat ../initramfs.cpio | cpio -t
find/me/if/you/can/file.txt
find/me/if/you/can
find/me/if/you
find/me/if
find/me
find
busybox-x86_64
sbin
proc
sys
bin
usr
usr/sbin
usr/bin
etc
etc/init.d
etc/inittab
etc/init.d/rcS
lib
lib/modules
1961 bloków

BUT:

$ qemu-system-x86_64 -nographic -serial mon:stdio \
	-kernel arch/x86/boot/bzImage \
	-append "root=/dev/ram console=ttyS0 rdinit=/busybox-x86_64 init" \
	-M q35 -initrd ../initramfs.cpio

# ls
bin             etc             linuxrc         sbin
busybox-x86_64  find            proc            sys
dev             lib             root            usr
/ # ls -l find
total 0

With the patch reverted the file /find/me/if/you/can/file.txt
is accessible:

$ scripts/gen_initramfs_list.sh ../test/ ../initramfs.list

#####################
# ../test/
# Last modified: 1534428527.0818855150

dir /find 775 1000 1000
dir /find/me 775 1000 1000
dir /find/me/if 775 1000 1000
dir /find/me/if/you 775 1000 1000
dir /find/me/if/you/can 775 1000 1000
file /find/me/if/you/can/file.txt ../test/find/me/if/you/can/file.txt 664 1000 1000

#####################
# ../initramfs.list
# Last modified: 1534433777.8384497600

file /busybox-x86_64 ../initramfs/busybox-x86_64 0755 0 0
dir /sbin 0755 0 0
dir /proc 0755 0 0
dir /sys 0755 0 0
dir /bin 0755 0 0
dir /usr 0755 0 0
dir /usr/sbin 0755 0 0
dir /usr/bin 0755 0 0
dir /etc 0755 0 0
dir /etc/init.d 0755 0 0
file /etc/inittab ../initramfs/inittab 0755 0 0
file /etc/init.d/rcS ../initramfs/rcS-x86_64 0755 0 0
dir /lib 0755 0 0
dir /lib/modules 0755 0 0

$ cat ../initramfs.cpio | cpio -t
find
find/me
find/me/if
find/me/if/you
find/me/if/you/can
find/me/if/you/can/file.txt
busybox-x86_64
sbin
proc
sys
bin
usr
usr/sbin
usr/bin
etc
etc/init.d
etc/inittab
etc/init.d/rcS
lib
lib/modules
1961 bloków

$ qemu-system-x86_64 -nographic -serial mon:stdio \
	-kernel arch/x86/boot/bzImage \
	-append "root=/dev/ram console=ttyS0 rdinit=/busybox-x86_64 init" \
	-M q35 -initrd ../initramfs.cpio

# find find/
find/
find/me
find/me/if
find/me/if/you
find/me/if/you/can
find/me/if/you/can/file.txt
/ #

Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@samsung.com>
---
 scripts/gen_initramfs_list.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/scripts/gen_initramfs_list.sh b/scripts/gen_initramfs_list.sh
index 10e528b..e5d7b03 100755
--- a/scripts/gen_initramfs_list.sh
+++ b/scripts/gen_initramfs_list.sh
@@ -174,7 +174,7 @@ dir_filelist() {
 	${dep_list}header "$1"
 
 	srcdir=$(echo "$1" | sed -e 's://*:/:g')
-	dirlist=$(find "${srcdir}" -printf "%p %m %U %G\n" | sort)
+	dirlist=$(find "${srcdir}" -printf "%p %m %U %G\n")
 
 	# If $dirlist is only one line, then the directory is empty
 	if [  "$(echo "${dirlist}" | wc -l)" -gt 1 ]; then
-- 
2.7.4

Re: [PATCH] Revert "kbuild: create deterministic initramfs directory listings"

[Bjørn Forsman]

On Thu, 16 Aug 2018 at 18:18, Andrzej Pietrasiewicz
<andrzej.p@samsung.com> wrote:
>
> This reverts commit 9e6e0d5f2a2713402cf9dce69b9f9b516e4185d2.
>
> The reverted commit introduces broken builds. Even though the cpio archive
> does contain all the specified files, it seems that the kernel, while
> populating rootfs, scans the cpio buffer linearly and fails to create
> files whose parent directories are nonexistent at the moment of this failed
> creation. As a result, such files are not accessible when kernel boots into
> initramfs.
>
> Here is how to reproduce, from inside kernel source directory, with the
> patch in question not reverted:
>
> $ mkdir -p ../test/find/me/if/you/can
> $ touch ../test/find/me/if/you/can/file.txt
> $ cat ../initramfs.list
> file /busybox-x86_64 ../initramfs/busybox-x86_64 0755 0 0
> dir /sbin 0755 0 0
> dir /proc 0755 0 0
> dir /sys 0755 0 0
> dir /bin 0755 0 0
> dir /usr 0755 0 0
> dir /usr/sbin 0755 0 0
> dir /usr/bin 0755 0 0
> dir /etc 0755 0 0
> dir /etc/init.d 0755 0 0
> file /etc/inittab ../initramfs/inittab 0755 0 0
> file /etc/init.d/rcS ../initramfs/rcS-x86_64 0755 0 0
> dir /lib 0755 0 0
> dir /lib/modules 0755 0 0
> $ ls ../initramfs
> busybox-x86_64  inittab  rcS-x86_64
> $ cat ../initramfs/inittab
> ::sysinit:/etc/init.d/rcS
> ::askfirst:-/bin/sh
> ::ctrlaltdel:/sbin/reboot
> ::shutdown:/sbin/swapoff -a
> ::shutdown:/sbin/umount -a -r
> ::restart:/sbin/init
> $ cat ../initramfs/rcS-x86_64
> #!/busybox-x86_64 sh
>
> /busybox-x86_64 --install
>
> mount -t proc none /proc
> mount -t sysfs none /sys
>
> mdev -s
> echo /sbin/mdev > /proc/sys/kernel/hotplug
> $ scripts/gen_initramfs_list.sh ../test/ ../initramfs.list
>
> #####################
> # ../test/
> # Last modified: 1534428527.0818855150
>
> file /find/me/if/you/can/file.txt ../test/find/me/if/you/can/file.txt 664 1000 1000
> dir /find/me/if/you/can 775 1000 1000
> dir /find/me/if/you 775 1000 1000
> dir /find/me/if 775 1000 1000
> dir /find/me 775 1000 1000
> dir /find 775 1000 1000

I'm unable to reproduce it. On my system the listing is sorted so that
it works (parent directories appear before files). I tried to run with
LANG=C and it also sorts correctly. What is your LANG=? I think we
better add a LANG=C somewhere in the kernel build system, because I
think you have a LANG= that makes it sort differently. A quick fix
would of course be to insert it right next to sort, but there may be
other places that may break due to LANG= settings.

Best regards,
Bjørn Forsman

Re: [PATCH] Revert "kbuild: create deterministic initramfs directory listings"

[Andrzej Pietrasiewicz]

Hi Bjørn,

W dniu 17.08.2018 o 01:34, Bjørn Forsman pisze:
> On Thu, 16 Aug 2018 at 18:18, Andrzej Pietrasiewicz
> <andrzej.p@samsung.com> wrote:
>>
>> This reverts commit 9e6e0d5f2a2713402cf9dce69b9f9b516e4185d2.
>>
>> The reverted commit introduces broken builds. Even though the cpio archive
>> does contain all the specified files, it seems that the kernel, while
>> populating rootfs, scans the cpio buffer linearly and fails to create
>> files whose parent directories are nonexistent at the moment of this failed
>> creation. As a result, such files are not accessible when kernel boots into
>> initramfs.
>>

<snip>

> 
> I'm unable to reproduce it. On my system the listing is sorted so that
> it works (parent directories appear before files). I tried to run with
> LANG=C and it also sorts correctly. What is your LANG=? I think we
> better add a LANG=C somewhere in the kernel build system, because I
> think you have a LANG= that makes it sort differently. A quick fix
> would of course be to insert it right next to sort, but there may be
> other places that may break due to LANG= settings.
> 

Thanks for the tip. My LANG is pl_PL.UTF-8. Indeed, prefixing the "sort"
invocation in question with LANG=C does solve the problem. I don't feel
competent enough to say whether this is the correct place for the fix,
or if the fix should be made elsewhere. Another option is that it is the
"sort" itself that should be fixed (or the locale, or both).

Would you be able (as the author of the patch in question) to check if
there are other locales which cause the problem?

Thanks,

Andrzej

Re: [PATCH] Revert "kbuild: create deterministic initramfs directory listings"

[Masahiro Yamada]

2018-08-17 16:47 GMT+09:00 Andrzej Pietrasiewicz <andrzej.p@samsung.com>:
> Hi Bjørn,
>
> W dniu 17.08.2018 o 01:34, Bjørn Forsman pisze:
>> On Thu, 16 Aug 2018 at 18:18, Andrzej Pietrasiewicz
>> <andrzej.p@samsung.com> wrote:
>>>
>>> This reverts commit 9e6e0d5f2a2713402cf9dce69b9f9b516e4185d2.
>>>
>>> The reverted commit introduces broken builds. Even though the cpio archive
>>> does contain all the specified files, it seems that the kernel, while
>>> populating rootfs, scans the cpio buffer linearly and fails to create
>>> files whose parent directories are nonexistent at the moment of this failed
>>> creation. As a result, such files are not accessible when kernel boots into
>>> initramfs.
>>>
>
> <snip>
>
>>
>> I'm unable to reproduce it. On my system the listing is sorted so that
>> it works (parent directories appear before files). I tried to run with
>> LANG=C and it also sorts correctly. What is your LANG=? I think we
>> better add a LANG=C somewhere in the kernel build system, because I
>> think you have a LANG= that makes it sort differently. A quick fix
>> would of course be to insert it right next to sort, but there may be
>> other places that may break due to LANG= settings.
>>
>
> Thanks for the tip. My LANG is pl_PL.UTF-8. Indeed, prefixing the "sort"
> invocation in question with LANG=C does solve the problem. I don't feel
> competent enough to say whether this is the correct place for the fix,
> or if the fix should be made elsewhere. Another option is that it is the
> "sort" itself that should be fixed (or the locale, or both).
>
> Would you be able (as the author of the patch in question) to check if
> there are other locales which cause the problem?
>
> Thanks,
>
> Andrzej


I cannot add LANG=C to the high-level of the build system at least
since it would break the localization.


-- 
Best Regards
Masahiro Yamada

[PATCH] kbuild: make sorting initramfs contents independent of locale

[Andrzej Pietrasiewicz]

Some LANG values (e.g. pl_PL.UTF-8) cause the sort command to output
files before their parent directories, which makes them inaccessible for
the kernel. In other words, when the kernel populates the rootfs, it is
unable to create files whose parent directories have not been yet created.

This patch makes sorting use the default (LANG=C) locale, which results in
correctly laid out initramfs images (parent directories before files).

Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@samsung.com>
---
 scripts/gen_initramfs_list.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/scripts/gen_initramfs_list.sh b/scripts/gen_initramfs_list.sh
index 10e528b..0aad760 100755
--- a/scripts/gen_initramfs_list.sh
+++ b/scripts/gen_initramfs_list.sh
@@ -174,7 +174,7 @@ dir_filelist() {
 	${dep_list}header "$1"
 
 	srcdir=$(echo "$1" | sed -e 's://*:/:g')
-	dirlist=$(find "${srcdir}" -printf "%p %m %U %G\n" | sort)
+	dirlist=$(find "${srcdir}" -printf "%p %m %U %G\n" | LANG=C sort)
 
 	# If $dirlist is only one line, then the directory is empty
 	if [  "$(echo "${dirlist}" | wc -l)" -gt 1 ]; then
-- 
2.7.4

Re: [PATCH] kbuild: make sorting initramfs contents independent of locale

[Masahiro Yamada]

2018-08-17 21:03 GMT+09:00 Andrzej Pietrasiewicz <andrzej.p@samsung.com>:
> Some LANG values (e.g. pl_PL.UTF-8) cause the sort command to output
> files before their parent directories, which makes them inaccessible for
> the kernel. In other words, when the kernel populates the rootfs, it is
> unable to create files whose parent directories have not been yet created.
>
> This patch makes sorting use the default (LANG=C) locale, which results in
> correctly laid out initramfs images (parent directories before files).
>
> Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@samsung.com>
> ---


Applied to linux-kbuild. Thanks!


>  scripts/gen_initramfs_list.sh | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/scripts/gen_initramfs_list.sh b/scripts/gen_initramfs_list.sh
> index 10e528b..0aad760 100755
> --- a/scripts/gen_initramfs_list.sh
> +++ b/scripts/gen_initramfs_list.sh
> @@ -174,7 +174,7 @@ dir_filelist() {
>         ${dep_list}header "$1"
>
>         srcdir=$(echo "$1" | sed -e 's://*:/:g')
> -       dirlist=$(find "${srcdir}" -printf "%p %m %U %G\n" | sort)
> +       dirlist=$(find "${srcdir}" -printf "%p %m %U %G\n" | LANG=C sort)
>
>         # If $dirlist is only one line, then the directory is empty
>         if [  "$(echo "${dirlist}" | wc -l)" -gt 1 ]; then
> --
> 2.7.4
>



-- 
Best Regards
Masahiro Yamada