Created attachment 507684 [details] emerge --info After emerge of any package which currently has any binary running, its /proc/$pid/exe symlink value changes from /path/to/binary to /var/tmp/portage/$CATEGORY/$PF/image/path/to/binary (deleted) Examples: # ls -l /proc/$(pgrep -u root -x sshd)/exe lrwxrwxrwx 1 root root 0 2 dec 10:52 /proc/29264/exe -> /usr/sbin/sshd # emerge -1 net-misc/openssh &>/dev/null # ls -l /proc/$(pgrep -u root -x sshd)/exe lrwxrwxrwx 1 root root 0 2 dec 10:52 /proc/29264/exe -> /var/tmp/portage/net-misc/openssh-7.5_p1-r3/image/usr/sbin/sshd (deleted) # ls -l /proc/$(pgrep -x named)/exe lrwxrwxrwx 1 named named 0 2 dec 10:54 /proc/8910/exe -> /usr/sbin/named # emerge -1 net-dns/bind &>/dev/null # ls -l /proc/$(pgrep -x named)/exe lrwxrwxrwx 1 named named 0 2 dec 10:54 /proc/8910/exe -> /var/tmp/portage/net-dns/bind-9.11.1_p3/image/usr/sbin/named (deleted) # ls -l /proc/$(pgrep -u root -x systemd)/exe lrwxrwxrwx 1 root root 0 22 nov 20:55 /proc/1/exe -> /usr/lib64/systemd/systemd # emerge -1 sys-apps/systemd &>/dev/null # ls -l /proc/$(pgrep -u root -x systemd)/exe lrwxrwxrwx 1 root root 0 22 nov 20:55 /proc/1/exe -> /var/tmp/portage/sys-apps/systemd-233-r6/image/usr/lib/systemd/systemd (deleted) Without emerge, I can reproduce something similar - /proc/$pid/exe symlink value changes: # systemctl restart sshd # ensure valid sshd /proc/$pid/exe symlink # ls -l /proc/$(pgrep -u root -x sshd)/exe lrwxrwxrwx 1 root root 0 2 dec 11:51 /proc/32339/exe -> /usr/sbin/sshd # cp -p /usr/sbin/sshd{,.save} # simulate new (compiled) binary/inode # mv /usr/sbin/sshd{,.moved} # simulate preserve action # ls -l /proc/$(pgrep -u root -x sshd)/exe lrwxrwxrwx 1 root root 0 2 dec 11:51 /proc/32339/exe -> /usr/sbin/sshd.moved # rm /usr/sbin/sshd.moved # simulate removal of preserved file # mv /usr/sbin/sshd{.save,} # simulate installation of new binary # ls -l /proc/$(pgrep -u root -x sshd)/exe /usr/sbin/sshd* lrwxrwxrwx 1 root root 0 2 dec 11:51 /proc/32339/exe -> /usr/sbin/sshd.moved (deleted) -rwxr-xr-x 1 root root 770808 2 dec 10:53 /usr/sbin/sshd So, it seems, at install time, emerge does something like this: 1. move current installed files to /var/tmp/portage/$CATEGORY/$PF/image/path/to/files (*this* causes the confusion) 2. install the new package/files in place 3. remove /var/tmp/portage/$CATEGORY/$PF/image/path/to/files Obviously this works but /proc/$pid/exe symlinks get confused by this. It beats me why emerge preserves current installed files (which get deleted anyway) but I if this preserve action is really needed, it would be better to simply copy it (something like this): 1. *copy* current installed files to /var/tmp/portage/$CATEGORY/$PF/image/path/to/files (*no* /proc/$pid/exe symlink value change) 2. install the new binary in place 3. remove /var/tmp/portage/$CATEGORY/$PF/image/path/to/files Example: # ls -l /proc/$(pgrep -u root -x sshd)/exe lrwxrwxrwx 1 root root 0 2 dec 11:55 /proc/304/exe -> /usr/sbin/sshd # cp -p /usr/sbin/sshd /usr/sbin/sshd.new # new compiled binary # cp -p /usr/sbin/sshd /usr/sbin/sshd.preserve # preserve/copy current binary # mv /usr/sbin/sshd.new /usr/sbin/sshd # install new compiled binary # rm /usr/sbin/sshd.preserve # remove the preserved/copied binary # ls -l /proc/$(pgrep -u root -x sshd)/exe lrwxrwxrwx 1 root root 0 2 dec 11:55 /proc/304/exe -> /usr/sbin/sshd (deleted) This way, /proc/$pid/exe symlinks will not get confused (contain internal portage values) about the current (still) running binary.
The kernel gets confused when portage uses the rename function to move files from /var/tmp/portage/ to the root filesystem. There's a workaround involving mounts suggested in bug 481320, comment #44.
Never thought this would be a kernel bug, looks like you're right: # ls -l /proc/$(pgrep -u root -x sshd)/exe lrwxrwxrwx 1 root root 0 3 dec 16:35 /proc/3584/exe -> /usr/sbin/sshd # cp -p /usr/sbin/sshd /var/tmp/portage/sshd # mv /var/tmp/portage/sshd /usr/sbin/sshd # ls -l /proc/$(pgrep -u root -x sshd)/exe lrwxrwxrwx 1 root root 0 3 dec 16:35 /proc/3584/exe -> /var/tmp/portage/sshd (deleted) Thanks!
