Ubuntu Cloud Archive

  1. Series ussuri
  2. Bug #1994002
  3. Comment #26

Comment 26 for bug 1994002

Revision history for this message
Mauricio Faria de Oliveira (mfo) wrote :

Verification done on kinetic-proposed.

The migration status during the race condition is
not 'active' (which is expected to have RAM info, but didn't)
but 'setup' (which is not, thus no issues).

(qemu) info migrate

-updates:
...
Migration status: active
total time: 0 ms

-proposed:
...
Migration status: setup
total time: 0 ms

Detailed steps:
==============

$ lxc launch ubuntu:kinetic qemu-k
$ lxc exec qemu-k -- su - ubuntu

Packages from -updates: FAIL
----------------------

$ sudo apt install --yes --no-install-recommends qemu-system-x86 gdb dpkg-dev

$ dpkg -s qemu-system-x86 | grep Version:
Version: 1:7.0+dfsg-7ubuntu2.1

...

Source: get line number for breakpoint.

$ sudo add-apt-repository -ys
$ apt source qemu

$ head -n1 qemu-*/debian/changelog
qemu (1:7.0+dfsg-7ubuntu2.1) kinetic-security; urgency=medium

$ vim qemu-*/migration/migration.c

1073 static void fill_source_migration_info(MigrationInfo *info)
1074 {
...
1100 case MIGRATION_STATUS_SETUP:
...
1103 break;
...

...

Terminal 1)

$ qemu-system-x86_64 -nodefaults -nographic -S -incoming tcp:0:4444

Terminal 2)

gdb \
  -ex 'set non-stop on' -ex 'set pagination off' -ex 'set confirm off' \
  -iex 'set debuginfod enabled on' -iex 'set debuginfod urls https://debuginfod.ubuntu.com' \
  qemu-system-x86_64

(gdb) b migrate_set_state
...
Breakpoint 1 at 0x47ed10: migrate_set_state. (2 locations)
(gdb) b migration/migration.c:1103
...
Breakpoint 2 at 0x47dba0: file ../../migration/migration.c, line 1103.

(gdb) run -nodefaults -nographic -S -monitor tcp:0:3333,server,wait=off

Terminal 3)

nc 127.0.0.1 3333

(qemu) migrate -d tcp:127.0.0.1:4444

Terminal 2)

Thread 1 "qemu-system-x86" hit Breakpoint 1, migrate_set_state (state=0x555556779618, old_state=0, new_state=1) at ../../migration/migration.c:1763

(gdb) p (MigrationStatus) 0
$1 = MIGRATION_STATUS_NONE
(gdb) p (MigrationStatus) 1
$2 = MIGRATION_STATUS_SETUP
(gdb) c

Thread 5 "qemu-system-x86" hit Breakpoint 1, migrate_set_state (state=0x555556779618, old_state=1, new_state=4) at ../../migration/migration.c:1763

(gdb) p (MigrationStatus) 1
$3 = MIGRATION_STATUS_SETUP
(gdb) p (MigrationStatus) 4
$4 = MIGRATION_STATUS_ACTIVE

Terminal 3)

(qemu) info migrate

Terminal 2)

Thread 1 "qemu-system-x86" hit Breakpoint 2, fill_source_migration_info (info=0x555556dc6c60) at ../../migration/migration.c:1103

(gdb) p (MigrationStatus) s.state
$6 = MIGRATION_STATUS_SETUP
(gdb) p info.status
$7 = MIGRATION_STATUS_NONE

(gdb) info threads
  Id Target Id Frame
* 1 Thread 0x7ffff6c32340 (LWP 2368) "qemu-system-x86" fill_source_migration_info (info=0x555556dc6c60) at ../../migration/migration.c:1103
  2 Thread 0x7ffff65ff6c0 (LWP 2369) "qemu-system-x86" (running)
  3 Thread 0x7ffff5d7c6c0 (LWP 2370) "qemu-system-x86" (running)
  5 Thread 0x7ffff49ff6c0 (LWP 2373) "qemu-system-x86" migrate_set_state (state=0x555556779618, old_state=1, new_state=4) at ../../migration/migration.c:1763

(gdb) thread 5
(gdb) continue &

(gdb) info threads
  Id Target Id Frame
  1 Thread 0x7ffff6c32340 (LWP 2368) "qemu-system-x86" fill_source_migration_info (info=0x555556dc6c60) at ../../migration/migration.c:1103
  2 Thread 0x7ffff65ff6c0 (LWP 2369) "qemu-system-x86" (running)
  3 Thread 0x7ffff5d7c6c0 (LWP 2370) "qemu-system-x86" (running)
* 5 Thread 0x7ffff49ff6c0 (LWP 2373) "qemu-system-x86" (running)

(gdb) thread 1

(gdb) p (MigrationStatus) s.state
$8 = MIGRATION_STATUS_ACTIVE
(gdb) c

Terminal 3)

...
Migration status: active
total time: 0 ms
(qemu)

Migration status is active, without any RAM statistics.

(qemu) quit
(gdb) quit

Terminal 1)

Ctrl-C

...

Packages from -proposed: PASS
-----------------------

$ sudo add-apt-repository -yp proposed
$ sudo add-apt-repository -ys # didn't work for proposed
$ echo 'deb-src http://archive.ubuntu.com/ubuntu kinetic-proposed main' | sudo tee -a /etc/apt/sources.list

$ sudo apt install --yes --no-install-recommends qemu-system-x86

$ dpkg -s qemu-system-x86 | grep Version:
Version: 1:7.0+dfsg-7ubuntu2.2

$ rm -rf qemu-*
a$ apt source qemu

$ head -n1 qemu-*/debian/changelog
qemu (1:7.0+dfsg-7ubuntu2.2) kinetic; urgency=medium

$ vim qemu-*/migration/migration.c

1073 static void fill_source_migration_info(MigrationInfo *info)
1074 {
...
1076 int state = qatomic_read(&s->state);
...
1101 case MIGRATION_STATUS_SETUP:
...
1104 break;

Terminal 1)

$ qemu-system-x86_64 -nodefaults -nographic -S -incoming tcp:0:4444

Terminal 2)

$ gdb -ex 'set non-stop on' -ex 'set pagination off' -ex 'set confirm off' -iex 'set debuginfod enabled on' -iex 'set debuginfod urls https://debuginfod.ubuntu.com' qemu-system-x86_64

(gdb) b migrate_set_state
...
Breakpoint 1 at 0x47ed20: migrate_set_state. (2 locations)
(gdb) b migration/migration.c:1104
...
Breakpoint 2 at 0x47dbc3: file ../../migration/migration.c, line 1104.

Terminal 3)

$ nc 127.0.0.1 3333
(qemu) migrate -d tcp:127.0.0.1:4444

Terminal 2)

Thread 1 "qemu-system-x86" hit Breakpoint 1, migrate_set_state (state=0x555556779618, old_state=0, new_state=1) at ../../migration/migration.c:1764

(gdb) p (MigrationStatus) 0
$1 = MIGRATION_STATUS_NONE
(gdb) p (MigrationStatus) 1
$2 = MIGRATION_STATUS_SETUP
(gdb) c

Thread 5 "qemu-system-x86" hit Breakpoint 1, migrate_set_state (state=0x555556779618, old_state=1, new_state=4) at ../../migration/migration.c:1764
1764 in ../../migration/migration.c
(gdb) p (MigrationStatus) 1
$3 = MIGRATION_STATUS_SETUP
(gdb) p (MigrationStatus) 4
$4 = MIGRATION_STATUS_ACTIVE

(qemu) info migrate

Terminal 2)

Thread 1 "qemu-system-x86" hit Breakpoint 2, fill_source_migration_info (info=0x555556dc6c60) at ../../migration/migration.c:1141

(gdb) p (MigrationStatus) s.state
$6 = MIGRATION_STATUS_SETUP
(gdb) p info.status
$7 = MIGRATION_STATUS_NONE

(gdb) info threads
  Id Target Id Frame
* 1 Thread 0x7ffff6c32340 (LWP 7562) "qemu-system-x86" fill_source_migration_info (info=0x555556dc6c60) at ../../migration/migration.c:1141
  2 Thread 0x7ffff65ff6c0 (LWP 7565) "qemu-system-x86" (running)
  3 Thread 0x7ffff5d7c6c0 (LWP 7566) "qemu-system-x86" (running)
  5 Thread 0x7fffa7dff6c0 (LWP 7569) "qemu-system-x86" migrate_set_state (state=0x555556779618, old_state=1, new_state=4) at ../../migration/migration.c:1764

(gdb) thread 5
(gdb) continue &

(gdb) info threads
  Id Target Id Frame
  1 Thread 0x7ffff6c32340 (LWP 7562) "qemu-system-x86" fill_source_migration_info (info=0x555556dc6c60) at ../../migration/migration.c:1141
  2 Thread 0x7ffff65ff6c0 (LWP 7565) "qemu-system-x86" (running)
  3 Thread 0x7ffff5d7c6c0 (LWP 7566) "qemu-system-x86" (running)
* 5 Thread 0x7fffa7dff6c0 (LWP 7569) "qemu-system-x86" (running)

(gdb) thread 1
(gdb) p (MigrationStatus) s.state
$8 = MIGRATION_STATUS_ACTIVE

(gdb) c

Terminal 3)

Status is now still 'SETUP' (which is not expected to have RAM statistics), not 'ACTIVE' (which is, and caused the issue).

...
Migration status: setup
total time: 0 ms