[Pkg-xen-devel] Bug#767295: xl: apparent memory leak

[Gedalya]

Package: xen-utils-4.4
Version: 4.4.1-3

When booting domU's running amd64 jessie, I notice some memory problems 
with xl.

root at xen:~# pmap -x 4121
4121:   /usr/lib/xen-4.4/bin/xl create --quiet --defconfig 
/etc/xen/auto/mail_deb80.cfg
Address           Kbytes     RSS   Dirty Mode  Mapping
0000000000400000     144     128       0 r-x-- xl
0000000000623000       4       4       4 r---- xl
0000000000624000       8       8       8 rw--- xl
0000000000626000       4       4       4 rw---   [ anon ]
0000000000841000     288     240     240 rw---   [ anon ]
00007f9ca48b4000   23852   14464   14464 rw---   [ anon ]
00007f9ca8000000     132       8       8 rw---   [ anon ]
00007f9ca8021000   65404       0       0 -----   [ anon ]
00007f9cae639000     104       0       0 r-x-- libz.so.1.2.8
<< snip >>
00007ffff736e000     132     104     104 rw---   [ stack ]
00007ffff73f4000       8       8       0 r-x--   [ anon ]
00007ffff73f6000       8       0       0 r----   [ anon ]
ffffffffff600000       4       0       0 r-x--   [ anon ]
---------------- ------- ------- -------
total kB          119812   17124   15052

After init 6 within the VM:

root at xen:~# pmap -x 4121
4121:   /usr/lib/xen-4.4/bin/xl create --quiet --defconfig 
/etc/xen/auto/mail_deb80.cfg
Address           Kbytes     RSS   Dirty Mode  Mapping
0000000000400000     144     144       0 r-x-- xl
0000000000623000       4       4       4 r---- xl
0000000000624000       8       8       8 rw--- xl
0000000000626000       4       4       4 rw---   [ anon ]
0000000000841000     288     288     288 rw---   [ anon ]
0000000000889000    2292    2292    2292 rw---   [ anon ]
00007f9ca3169000   23852   14464   14464 rw---   [ anon ]
00007f9ca48b4000   23852   14464   14464 rw---   [ anon ]
00007f9ca8000000     132       8       8 rw---   [ anon ]
00007f9ca8021000   65404       0       0 -----   [ anon ]
00007f9cae639000     104      88       0 r-x-- libz.so.1.2.8
<< snip >>
---------------- ------- ------- -------
total kB          145964   34620   31864

another init 6:

root at xen:~# pmap -x 4121
4121:   /usr/lib/xen-4.4/bin/xl create --quiet --defconfig 
/etc/xen/auto/mail_deb80.cfg
Address           Kbytes     RSS   Dirty Mode  Mapping
0000000000400000     144     144       0 r-x-- xl
0000000000623000       4       4       4 r---- xl
0000000000624000       8       8       8 rw--- xl
0000000000626000       4       4       4 rw---   [ anon ]
0000000000841000     288     288     288 rw---   [ anon ]
0000000000889000    2292    2292    2292 rw---   [ anon ]
00007f9ca1a1e000   23852   14464   14464 rw---   [ anon ]
00007f9ca3169000   23852   14464   14464 rw---   [ anon ]
00007f9ca48b4000   23852   14464   14464 rw---   [ anon ]
<< snip >>
---------------- ------- ------- -------
total kB          169816   49084   46328



---------------

For my older domUs running i386 wheezy, the initial size of xl is hugely 
smaller:

# pmap -x 10380
10380:   /usr/lib/xen-4.4/bin/xl create aptcache_deb70.cfg
Address           Kbytes     RSS   Dirty Mode  Mapping
0000000000400000     144     128       0 r-x-- xl
0000000000623000       4       4       4 r---- xl
0000000000624000       8       8       8 rw--- xl
0000000000626000       4       4       4 rw---   [ anon ]
00000000015e3000     132     132     132 rw---   [ anon ]
00007fb484000000     132       8       8 rw---   [ anon ]
00007fb484021000   65404       0       0 -----   [ anon ]
00007fb4893d4000     104       0       0 r-x-- libz.so.1.2.8
<< snip >>
---------------- ------- ------- -------
total kB           95808    2604     488

After first init 6:

# pmap -x 10380
10380:   /usr/lib/xen-4.4/bin/xl create aptcache_deb70.cfg
Address           Kbytes     RSS   Dirty Mode  Mapping
0000000000400000     144     144       0 r-x-- xl
0000000000623000       4       4       4 r---- xl
0000000000624000       8       8       8 rw--- xl
0000000000626000       4       4       4 rw---   [ anon ]
00000000015e3000     132     132     132 rw---   [ anon ]
0000000001604000    5840    5780    5780 rw---   [ anon ]
00007fb484000000     132       8       8 rw---   [ anon ]
00007fb484021000   65404       0       0 -----   [ anon ]
00007fb4893d4000     104     100       0 r-x-- libz.so.1.2.8
<< snip >>
---------------- ------- ------- -------
total kB          101656    8792    6276

And subsequent reboots don't make it grow any more.