[PATCH 0/4] Fix sporadic failures in do_wic_image

[PATCH 0/4] Fix sporadic failures in do_wic_image

[Felix Moessbauer]

This patch series fixes mounting and task odering issues around do_wic_image.
These have previously been reported by H. Schild in "[PATCH v14 0/2] CPIO & OVA Images".

While patch 1,2 and 3 fix the issue, patch 4 splits the do_rootfs task to avoid open mountpoints
after the wic task.

Probably we do not want to integrate patch 4 until decisions on the mounting in general are made.

Best regards,
Felix

Felix Moessbauer (4):
  fix typo in do_rootfs_finalize
  execute do_wic_image under a lock to ensure mountpoints remain mounted
  fix race by serialize rootfs_finalize and do_wic_image
  split rootfs finalization and unmounting into two tasks

 meta/classes/image.bbclass   | 49 +++++++++++++++++++++++++-----------
 meta/classes/wic-img.bbclass | 36 +++++++++++++++-----------
 2 files changed, 56 insertions(+), 29 deletions(-)

-- 
2.30.2

[PATCH 1/4] fix typo in do_rootfs_finalize

[Felix Moessbauer]

This fixes a typo to make sure the same mountpoint is checked for
existence and unmounted.

Signed-off-by: Felix Moessbauer <felix.moessbauer@siemens.com>
---
 meta/classes/image.bbclass | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/meta/classes/image.bbclass b/meta/classes/image.bbclass
index ec93cab..1f39690 100644
--- a/meta/classes/image.bbclass
+++ b/meta/classes/image.bbclass
@@ -200,7 +200,7 @@ do_rootfs_finalize() {
 
         mountpoint -q '${ROOTFSDIR}/dev' && \
             umount -l ${ROOTFSDIR}/dev
-        mountpoint -q '${ROOTFSDIR}/sys' && \
+        mountpoint -q '${ROOTFSDIR}/proc' && \
             umount -l ${ROOTFSDIR}/proc
         mountpoint -q '${ROOTFSDIR}/sys' && \
             umount -l ${ROOTFSDIR}/sys
-- 
2.30.2

Re: [PATCH 1/4] fix typo in do_rootfs_finalize

[Henning Schild]

ACK. Should go stand-alone in case discussions on the series take time.

But makes we wonder if we can write this as

for point in dev proc sys; do
...
done

that would probably shorten the whole thing, and the next addition of a
mointpoint will likely not make copy/paste mistakes

Henning

Am Wed, 22 Sep 2021 11:27:51 +0200
schrieb Felix Moessbauer <felix.moessbauer@siemens.com>:

> This fixes a typo to make sure the same mountpoint is checked for
> existence and unmounted.
> 
> Signed-off-by: Felix Moessbauer <felix.moessbauer@siemens.com>
> ---
>  meta/classes/image.bbclass | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/meta/classes/image.bbclass b/meta/classes/image.bbclass
> index ec93cab..1f39690 100644
> --- a/meta/classes/image.bbclass
> +++ b/meta/classes/image.bbclass
> @@ -200,7 +200,7 @@ do_rootfs_finalize() {
>  
>          mountpoint -q '${ROOTFSDIR}/dev' && \
>              umount -l ${ROOTFSDIR}/dev
> -        mountpoint -q '${ROOTFSDIR}/sys' && \
> +        mountpoint -q '${ROOTFSDIR}/proc' && \
>              umount -l ${ROOTFSDIR}/proc
>          mountpoint -q '${ROOTFSDIR}/sys' && \
>              umount -l ${ROOTFSDIR}/sys

[PATCH 2/4] execute do_wic_image under a lock to ensure mountpoints remain mounted

[Felix Moessbauer]

This patch adds the isar.lock to the do_wic_image task to ensure that
the mountpoints are not unmounted by a simultaneously running wic task.
Further, it makes mounting more robust by executing the
wic task in a try / finally handler so that the mount points are
unmounted even if the task itself fails.

Signed-off-by: Felix Moessbauer <felix.moessbauer@siemens.com>
---
 meta/classes/wic-img.bbclass | 36 ++++++++++++++++++++++--------------
 1 file changed, 22 insertions(+), 14 deletions(-)

diff --git a/meta/classes/wic-img.bbclass b/meta/classes/wic-img.bbclass
index d849ad9..e495c12 100644
--- a/meta/classes/wic-img.bbclass
+++ b/meta/classes/wic-img.bbclass
@@ -138,23 +138,40 @@ python check_for_wic_warnings() {
 
 do_wic_image[file-checksums] += "${WKS_FILE_CHECKSUM}"
 python do_wic_image() {
-    bb.build.exec_func("generate_wic_image", d)
-    bb.build.exec_func("check_for_wic_warnings", d)
+    lock = bb.utils.lockfile(d.getVar("REPO_ISAR_DIR") + "/isar.lock", shared=True)
+    bb.build.exec_func("wic_do_mounts", d)
+    try:
+        bb.build.exec_func("generate_wic_image", d)
+        bb.build.exec_func("check_for_wic_warnings", d)
+    finally:
+        bb.build.exec_func("wic_undo_mounts", d)
+        bb.utils.unlockfile(lock)
 }
 addtask wic_image before do_image after do_image_tools
 
-generate_wic_image() {
+wic_do_mounts() {
     buildchroot_do_mounts
     sudo -s <<'EOSUDO'
-        ( flock 9
         for dir in ${BBLAYERS} ${STAGING_DIR} ${SCRIPTSDIR} ${BITBAKEDIR}; do
             mkdir -p ${BUILDCHROOT_DIR}/$dir
             if ! mountpoint ${BUILDCHROOT_DIR}/$dir >/dev/null 2>&1; then
                 mount --bind --make-private $dir ${BUILDCHROOT_DIR}/$dir
             fi
         done
-        ) 9>${MOUNT_LOCKFILE}
 EOSUDO
+}
+
+wic_undo_mounts() {
+    sudo -s <<'EOSUDO'
+        for dir in ${BBLAYERS} ${STAGING_DIR} ${SCRIPTSDIR} ${BITBAKEDIR}; do
+            if mountpoint -q ${BUILDCHROOT_DIR}/$dir; then
+                umount ${BUILDCHROOT_DIR}/$dir
+            fi
+        done
+EOSUDO
+}
+
+generate_wic_image() {
     export FAKEROOTCMD=${FAKEROOTCMD}
     export BUILDDIR=${BUILDDIR}
     export MTOOLS_SKIP_CHECK=1
@@ -200,13 +217,4 @@ EOSUDO
     done
     rm -rf ${BUILDCHROOT_DIR}/${WICTMP}
     rm -rf ${IMAGE_ROOTFS}/../pseudo
-    sudo -s <<'EOSUDO'
-        ( flock 9
-        for dir in ${BBLAYERS} ${STAGING_DIR} ${SCRIPTSDIR} ${BITBAKEDIR}; do
-            if mountpoint -q ${BUILDCHROOT_DIR}/$dir; then
-                umount ${BUILDCHROOT_DIR}/$dir
-            fi
-        done
-        ) 9>${MOUNT_LOCKFILE}
-EOSUDO
 }
-- 
2.30.2

Re: [PATCH 2/4] execute do_wic_image under a lock to ensure mountpoints remain mounted

[Henning Schild]

LGTM

Henning

Am Wed, 22 Sep 2021 11:27:52 +0200
schrieb Felix Moessbauer <felix.moessbauer@siemens.com>:

> This patch adds the isar.lock to the do_wic_image task to ensure that
> the mountpoints are not unmounted by a simultaneously running wic
> task. Further, it makes mounting more robust by executing the
> wic task in a try / finally handler so that the mount points are
> unmounted even if the task itself fails.
> 
> Signed-off-by: Felix Moessbauer <felix.moessbauer@siemens.com>
> ---
>  meta/classes/wic-img.bbclass | 36
> ++++++++++++++++++++++-------------- 1 file changed, 22
> insertions(+), 14 deletions(-)
> 
> diff --git a/meta/classes/wic-img.bbclass
> b/meta/classes/wic-img.bbclass index d849ad9..e495c12 100644
> --- a/meta/classes/wic-img.bbclass
> +++ b/meta/classes/wic-img.bbclass
> @@ -138,23 +138,40 @@ python check_for_wic_warnings() {
>  
>  do_wic_image[file-checksums] += "${WKS_FILE_CHECKSUM}"
>  python do_wic_image() {
> -    bb.build.exec_func("generate_wic_image", d)
> -    bb.build.exec_func("check_for_wic_warnings", d)
> +    lock = bb.utils.lockfile(d.getVar("REPO_ISAR_DIR") +
> "/isar.lock", shared=True)
> +    bb.build.exec_func("wic_do_mounts", d)
> +    try:
> +        bb.build.exec_func("generate_wic_image", d)
> +        bb.build.exec_func("check_for_wic_warnings", d)
> +    finally:
> +        bb.build.exec_func("wic_undo_mounts", d)
> +        bb.utils.unlockfile(lock)
>  }
>  addtask wic_image before do_image after do_image_tools
>  
> -generate_wic_image() {
> +wic_do_mounts() {
>      buildchroot_do_mounts
>      sudo -s <<'EOSUDO'
> -        ( flock 9
>          for dir in ${BBLAYERS} ${STAGING_DIR} ${SCRIPTSDIR}
> ${BITBAKEDIR}; do mkdir -p ${BUILDCHROOT_DIR}/$dir
>              if ! mountpoint ${BUILDCHROOT_DIR}/$dir >/dev/null 2>&1;
> then mount --bind --make-private $dir ${BUILDCHROOT_DIR}/$dir
>              fi
>          done
> -        ) 9>${MOUNT_LOCKFILE}
>  EOSUDO
> +}
> +
> +wic_undo_mounts() {
> +    sudo -s <<'EOSUDO'
> +        for dir in ${BBLAYERS} ${STAGING_DIR} ${SCRIPTSDIR}
> ${BITBAKEDIR}; do
> +            if mountpoint -q ${BUILDCHROOT_DIR}/$dir; then
> +                umount ${BUILDCHROOT_DIR}/$dir
> +            fi
> +        done
> +EOSUDO
> +}
> +
> +generate_wic_image() {
>      export FAKEROOTCMD=${FAKEROOTCMD}
>      export BUILDDIR=${BUILDDIR}
>      export MTOOLS_SKIP_CHECK=1
> @@ -200,13 +217,4 @@ EOSUDO
>      done
>      rm -rf ${BUILDCHROOT_DIR}/${WICTMP}
>      rm -rf ${IMAGE_ROOTFS}/../pseudo
> -    sudo -s <<'EOSUDO'
> -        ( flock 9
> -        for dir in ${BBLAYERS} ${STAGING_DIR} ${SCRIPTSDIR}
> ${BITBAKEDIR}; do
> -            if mountpoint -q ${BUILDCHROOT_DIR}/$dir; then
> -                umount ${BUILDCHROOT_DIR}/$dir
> -            fi
> -        done
> -        ) 9>${MOUNT_LOCKFILE}
> -EOSUDO
>  }

[PATCH 3/4] fix race by serialize rootfs_finalize and do_wic_image

[Felix Moessbauer]

The do_wic_image task requires a mounted buildchroot.
Prior to this patch, the wic_do_mounts task and do_rootfs_finalize
were not ordered. By that, the do_rootfs_finalize task could run
in parallel and unmount the buildchroot.

This is now fixed by adding the do_rootfs_finalize as a task dependency.

Signed-off-by: Felix Moessbauer <felix.moessbauer@siemens.com>
---
 meta/classes/wic-img.bbclass | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/meta/classes/wic-img.bbclass b/meta/classes/wic-img.bbclass
index e495c12..573537c 100644
--- a/meta/classes/wic-img.bbclass
+++ b/meta/classes/wic-img.bbclass
@@ -147,7 +147,7 @@ python do_wic_image() {
         bb.build.exec_func("wic_undo_mounts", d)
         bb.utils.unlockfile(lock)
 }
-addtask wic_image before do_image after do_image_tools
+addtask wic_image before do_image after do_image_tools do_rootfs_finalize
 
 wic_do_mounts() {
     buildchroot_do_mounts
-- 
2.30.2

Re: [PATCH 3/4] fix race by serialize rootfs_finalize and do_wic_image

[Henning Schild]

Am Wed, 22 Sep 2021 11:27:53 +0200
schrieb Felix Moessbauer <felix.moessbauer@siemens.com>:

> The do_wic_image task requires a mounted buildchroot.
> Prior to this patch, the wic_do_mounts task and do_rootfs_finalize
> were not ordered. By that, the do_rootfs_finalize task could run
> in parallel and unmount the buildchroot.

That is not just a mounting issue. The finalize should be done before
any imager goes to create an image. Because finalize contains quite a
bit of "rm -f".

If the actual imager task and finalize have not been serialized, we
need to look into that for all our imagers, not just wic.

The pattern we use is that imagers usually do

addtask <something>_image before do_image after do_image_tools

and it is also in ubifs cpiogz ext4 fit container ...

We need to touch all of them. Or play a global trick like

addtask image_tools after do_rootfs_finalize

to catch them all and possibly also catch the ones in layers.

Henning

> This is now fixed by adding the do_rootfs_finalize as a task
> dependency.
> 
> Signed-off-by: Felix Moessbauer <felix.moessbauer@siemens.com>
> ---
>  meta/classes/wic-img.bbclass | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/meta/classes/wic-img.bbclass
> b/meta/classes/wic-img.bbclass index e495c12..573537c 100644
> --- a/meta/classes/wic-img.bbclass
> +++ b/meta/classes/wic-img.bbclass
> @@ -147,7 +147,7 @@ python do_wic_image() {
>          bb.build.exec_func("wic_undo_mounts", d)
>          bb.utils.unlockfile(lock)
>  }
> -addtask wic_image before do_image after do_image_tools
> +addtask wic_image before do_image after do_image_tools
> do_rootfs_finalize 
>  wic_do_mounts() {
>      buildchroot_do_mounts

RE: [PATCH 3/4] fix race by serialize rootfs_finalize and do_wic_image

[Moessbauer, Felix]

Hi,

I had a second look at the task graph and this patch is wrong / redundant.
The do_image_tools task already depends on do_rootfs which itself depends on do_rootfs_finalize.

By that, also the splitting of the finalize / unmount in patch 4 does not work out.
This likely explains why we get a deadlock in do_container_image when building a container image which is then included into a regular wic image with this patch series.

What really helped is to have a look at the task dependency graph which can be exported as dot file:
bitbake -g recipe-name -u ncurses
xdot build/task-depends.dot

I'll send out a v2 soon, containing just the first two patches.

Best regards,
Felix

> -----Original Message-----
> From: Henning Schild <henning.schild@siemens.com>
> Sent: Wednesday, September 22, 2021 5:15 PM
> To: Moessbauer, Felix (T RDA IOT SES-DE)
> <felix.moessbauer@siemens.com>
> Cc: isar-users@googlegroups.com; Kiszka, Jan (T RDA IOT)
> <jan.kiszka@siemens.com>
> Subject: Re: [PATCH 3/4] fix race by serialize rootfs_finalize and
> do_wic_image
> 
> Am Wed, 22 Sep 2021 11:27:53 +0200
> schrieb Felix Moessbauer <felix.moessbauer@siemens.com>:
> 
> > The do_wic_image task requires a mounted buildchroot.
> > Prior to this patch, the wic_do_mounts task and do_rootfs_finalize
> > were not ordered. By that, the do_rootfs_finalize task could run in
> > parallel and unmount the buildchroot.
> 
> That is not just a mounting issue. The finalize should be done before any
> imager goes to create an image. Because finalize contains quite a bit of "rm -
> f".
> 
> If the actual imager task and finalize have not been serialized, we need to
> look into that for all our imagers, not just wic.
> 
> The pattern we use is that imagers usually do
> 
> addtask <something>_image before do_image after do_image_tools
> 
> and it is also in ubifs cpiogz ext4 fit container ...
> 
> We need to touch all of them. Or play a global trick like
> 
> addtask image_tools after do_rootfs_finalize
> 
> to catch them all and possibly also catch the ones in layers.
> 
> Henning
> 
> > This is now fixed by adding the do_rootfs_finalize as a task
> > dependency.
> >
> > Signed-off-by: Felix Moessbauer <felix.moessbauer@siemens.com>
> > ---
> >  meta/classes/wic-img.bbclass | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/meta/classes/wic-img.bbclass
> > b/meta/classes/wic-img.bbclass index e495c12..573537c 100644
> > --- a/meta/classes/wic-img.bbclass
> > +++ b/meta/classes/wic-img.bbclass
> > @@ -147,7 +147,7 @@ python do_wic_image() {
> >          bb.build.exec_func("wic_undo_mounts", d)
> >          bb.utils.unlockfile(lock)
> >  }
> > -addtask wic_image before do_image after do_image_tools
> > +addtask wic_image before do_image after do_image_tools
> > do_rootfs_finalize
> >  wic_do_mounts() {
> >      buildchroot_do_mounts

[PATCH 4/4] split rootfs finalization and unmounting into two tasks

[Felix Moessbauer]

This patch separates the unmounting logic from do_rootfs_finalize
to inject tasks in between. By that, the do_wic_image tasks can
use the mount-points and finally everything is unmounted correctly.

Signed-off-by: Felix Moessbauer <felix.moessbauer@siemens.com>
---
 meta/classes/image.bbclass   | 49 +++++++++++++++++++++++++-----------
 meta/classes/wic-img.bbclass |  4 +--
 2 files changed, 36 insertions(+), 17 deletions(-)

diff --git a/meta/classes/image.bbclass b/meta/classes/image.bbclass
index 1f39690..988f0d7 100644
--- a/meta/classes/image.bbclass
+++ b/meta/classes/image.bbclass
@@ -190,21 +190,6 @@ do_rootfs_finalize() {
             find "${ROOTFSDIR}/usr/bin" \
                 -maxdepth 1 -name 'qemu-*-static' -type f -delete
 
-        mountpoint -q '${ROOTFSDIR}/isar-apt' && \
-            umount -l ${ROOTFSDIR}/isar-apt
-        rmdir --ignore-fail-on-non-empty ${ROOTFSDIR}/isar-apt
-
-        mountpoint -q '${ROOTFSDIR}/base-apt' && \
-            umount -l ${ROOTFSDIR}/base-apt
-        rmdir --ignore-fail-on-non-empty ${ROOTFSDIR}/base-apt
-
-        mountpoint -q '${ROOTFSDIR}/dev' && \
-            umount -l ${ROOTFSDIR}/dev
-        mountpoint -q '${ROOTFSDIR}/proc' && \
-            umount -l ${ROOTFSDIR}/proc
-        mountpoint -q '${ROOTFSDIR}/sys' && \
-            umount -l ${ROOTFSDIR}/sys
-
         rm -f "${ROOTFSDIR}/etc/apt/apt.conf.d/55isar-fallback.conf"
 
         rm -f "${ROOTFSDIR}/etc/apt/sources.list.d/isar-apt.list"
@@ -219,5 +204,39 @@ EOSUDO
 }
 addtask rootfs_finalize before do_rootfs after do_rootfs_postprocess
 
+do_rootfs_unmount() {
+    sudo -s <<'EOSUDO'
+        ret=0
+        if mountpoint -q '${ROOTFSDIR}/isar-apt'; then
+            umount -vl ${ROOTFSDIR}/isar-apt || ret=1
+        fi
+        if test -d ${ROOTFSDIR}/isar-apt; then
+            rmdir --ignore-fail-on-non-empty ${ROOTFSDIR}/isar-apt || ret=1
+        fi
+
+        if mountpoint -q ${ROOTFSDIR}/base-apt; then
+            umount -vl ${ROOTFSDIR}/base-apt || ret=1
+        fi
+        if test -d ${ROOTFSDIR}/base-apt; then
+            rmdir --ignore-fail-on-non-empty ${ROOTFSDIR}/base-apt || ret=1
+        fi
+
+        if mountpoint -q ${ROOTFSDIR}/dev; then
+            umount -vl ${ROOTFSDIR}/dev || ret=1
+        fi
+        if mountpoint -q ${ROOTFSDIR}/proc; then
+            umount -vl ${ROOTFSDIR}/proc || ret=1
+        fi
+        if mountpoint -q '${ROOTFSDIR}/sys'; then
+            umount -vl ${ROOTFSDIR}/sys || ret=1
+        fi
+
+        if [$ret -ne 0]; then
+            bbwarn "could not unmount all mountpoints"
+        fi
+EOSUDO
+}
+addtask rootfs_unmount before do_build after do_rootfs_finalize
+
 # Last so that the image type can overwrite tasks if needed
 inherit ${IMAGE_TYPE}
diff --git a/meta/classes/wic-img.bbclass b/meta/classes/wic-img.bbclass
index 573537c..0f5932b 100644
--- a/meta/classes/wic-img.bbclass
+++ b/meta/classes/wic-img.bbclass
@@ -142,12 +142,12 @@ python do_wic_image() {
     bb.build.exec_func("wic_do_mounts", d)
     try:
         bb.build.exec_func("generate_wic_image", d)
-        bb.build.exec_func("check_for_wic_warnings", d)
     finally:
         bb.build.exec_func("wic_undo_mounts", d)
         bb.utils.unlockfile(lock)
+    bb.build.exec_func("check_for_wic_warnings", d)
 }
-addtask wic_image before do_image after do_image_tools do_rootfs_finalize
+addtask wic_image before do_image do_rootfs_unmount after do_image_tools
 
 wic_do_mounts() {
     buildchroot_do_mounts
-- 
2.30.2

Re: [PATCH 4/4] split rootfs finalization and unmounting into two tasks

[Henning Schild]

That split is nice. But i would try and run it always after in a catch
block, not in another task.
That way it will become more robust while not having to touch the
task-chain ... which is not nice for layers that hook in "low".

I would not hold this one back for a series of "improved mounting" ...
divide and conquer! If it fixes an issue it is valid, only if you have
the time to do a full "mount rework" i would hold it back.

Henning

Am Wed, 22 Sep 2021 11:27:54 +0200
schrieb Felix Moessbauer <felix.moessbauer@siemens.com>:

> This patch separates the unmounting logic from do_rootfs_finalize
> to inject tasks in between. By that, the do_wic_image tasks can
> use the mount-points and finally everything is unmounted correctly.
> 
> Signed-off-by: Felix Moessbauer <felix.moessbauer@siemens.com>
> ---
>  meta/classes/image.bbclass   | 49
> +++++++++++++++++++++++++----------- meta/classes/wic-img.bbclass |
> 4 +-- 2 files changed, 36 insertions(+), 17 deletions(-)
> 
> diff --git a/meta/classes/image.bbclass b/meta/classes/image.bbclass
> index 1f39690..988f0d7 100644
> --- a/meta/classes/image.bbclass
> +++ b/meta/classes/image.bbclass
> @@ -190,21 +190,6 @@ do_rootfs_finalize() {
>              find "${ROOTFSDIR}/usr/bin" \
>                  -maxdepth 1 -name 'qemu-*-static' -type f -delete
>  
> -        mountpoint -q '${ROOTFSDIR}/isar-apt' && \
> -            umount -l ${ROOTFSDIR}/isar-apt
> -        rmdir --ignore-fail-on-non-empty ${ROOTFSDIR}/isar-apt
> -
> -        mountpoint -q '${ROOTFSDIR}/base-apt' && \
> -            umount -l ${ROOTFSDIR}/base-apt
> -        rmdir --ignore-fail-on-non-empty ${ROOTFSDIR}/base-apt
> -
> -        mountpoint -q '${ROOTFSDIR}/dev' && \
> -            umount -l ${ROOTFSDIR}/dev
> -        mountpoint -q '${ROOTFSDIR}/proc' && \
> -            umount -l ${ROOTFSDIR}/proc
> -        mountpoint -q '${ROOTFSDIR}/sys' && \
> -            umount -l ${ROOTFSDIR}/sys
> -
>          rm -f "${ROOTFSDIR}/etc/apt/apt.conf.d/55isar-fallback.conf"
>  
>          rm -f "${ROOTFSDIR}/etc/apt/sources.list.d/isar-apt.list"
> @@ -219,5 +204,39 @@ EOSUDO
>  }
>  addtask rootfs_finalize before do_rootfs after do_rootfs_postprocess
>  
> +do_rootfs_unmount() {
> +    sudo -s <<'EOSUDO'
> +        ret=0
> +        if mountpoint -q '${ROOTFSDIR}/isar-apt'; then
> +            umount -vl ${ROOTFSDIR}/isar-apt || ret=1
> +        fi
> +        if test -d ${ROOTFSDIR}/isar-apt; then
> +            rmdir --ignore-fail-on-non-empty ${ROOTFSDIR}/isar-apt
> || ret=1
> +        fi
> +
> +        if mountpoint -q ${ROOTFSDIR}/base-apt; then
> +            umount -vl ${ROOTFSDIR}/base-apt || ret=1
> +        fi
> +        if test -d ${ROOTFSDIR}/base-apt; then
> +            rmdir --ignore-fail-on-non-empty ${ROOTFSDIR}/base-apt
> || ret=1
> +        fi
> +
> +        if mountpoint -q ${ROOTFSDIR}/dev; then
> +            umount -vl ${ROOTFSDIR}/dev || ret=1
> +        fi
> +        if mountpoint -q ${ROOTFSDIR}/proc; then
> +            umount -vl ${ROOTFSDIR}/proc || ret=1
> +        fi
> +        if mountpoint -q '${ROOTFSDIR}/sys'; then
> +            umount -vl ${ROOTFSDIR}/sys || ret=1
> +        fi
> +
> +        if [$ret -ne 0]; then
> +            bbwarn "could not unmount all mountpoints"
> +        fi
> +EOSUDO
> +}
> +addtask rootfs_unmount before do_build after do_rootfs_finalize
> +
>  # Last so that the image type can overwrite tasks if needed
>  inherit ${IMAGE_TYPE}
> diff --git a/meta/classes/wic-img.bbclass
> b/meta/classes/wic-img.bbclass index 573537c..0f5932b 100644
> --- a/meta/classes/wic-img.bbclass
> +++ b/meta/classes/wic-img.bbclass
> @@ -142,12 +142,12 @@ python do_wic_image() {
>      bb.build.exec_func("wic_do_mounts", d)
>      try:
>          bb.build.exec_func("generate_wic_image", d)
> -        bb.build.exec_func("check_for_wic_warnings", d)
>      finally:
>          bb.build.exec_func("wic_undo_mounts", d)
>          bb.utils.unlockfile(lock)
> +    bb.build.exec_func("check_for_wic_warnings", d)
>  }
> -addtask wic_image before do_image after do_image_tools
> do_rootfs_finalize +addtask wic_image before do_image
> do_rootfs_unmount after do_image_tools 
>  wic_do_mounts() {
>      buildchroot_do_mounts