| title: | Re C R sleepers dont wake up on restart |
|
Hi,
Sukadev Bhattiprolu wrote:
Oren Laadan [orenl@xxxxxxxxxxxxxxx] wrote:
|
| I just posted v14-rc3 which includes the c/r of restart-blocks.
| That should improve the situation.
|
| However, depending on which syscalls one uses, process may still
| seem "stuck" after restart because the current code still does
| not save signals nor task timers; If a signal was pending (SIGALRM
| for example) after freezing but before checkpoint, it will be lost.
| If a timer was set at checkpoint, it will not be restored.
|
| So depending on your program, you may still experience issues
| until I add patches to handle that.
Ok, Just an fyi, the original program seemed to work fine, but when
I try to restart a small process tree, I get stuck on restart again.
I am running on v14-rc3 branch. Has this got anything to do with
pending SIGCHLD ? Seems to be easier to repro with larger process
trees (2 children per process, 4 or more levels deep).
Could be. You can verify by adding a couple of lines of code to
the checkpoint to complain if there are signals pending on a task
that is being checkpointed.
BTW, current code disregards Zombie processes.
Support for both (signals and zombies) is in the queue.
Oren.
Test programs (attached) (they need some cleanup though)
ptree2.c
p2.loop
--------- Processes after restart:
$ ps -ef|grep ptree
root 10461 10459 0 22:07 pts/0 00:00:00 ./ptree2 -n 1 -d 2
root 10465 10461 0 22:07 pts/0 00:00:00 ./ptree2 -n 1 -d 2
root 10466 10465 0 22:07 pts/0 00:00:00 [ptree2] <defunct
root 10479 8220 0 22:09 pts/1 00:00:00 grep ptree
---------- Process stacks
tree2 S f6270a90 0 10461 10459
f5e59380 00000082 08048a86 f6270a90 f6270bfc c2b32260 00000000 0000d9d3
f5f423b0 00000000 ffffffff 00000000 00000000 00000001 00000000 f6270a88
00000000 f6270a90 00000000 c02243aa 00000004 00000003 0000000c 00000006
Call Trace:
[<c02243aa ] do_wait+0x1dd/0x2f6
[<c021cd14 ] default_wake_function+0x0/0x8
[<c0224542 ] sys_wait4+0x7f/0x92
[<c0224568 ] sys_waitpid+0x13/0x17
[<c0202ce5 ] sysenter_do_call+0x12/0x25
[<c0510000 ] rtl8139_init_one+0x5ae/0x887
ptree2 S f5f423b0 0 10465 10461
f6002180 00000082 c2b265c8 f5f423b0 f5f4251c c2b29260 f67b1f44 e06d0177
00000282 c023363c c2b265c8 00000000 00000282 0000c350 00000001 0000c350
00000001 f67b1f44 0000c350 c051be99 00000000 00000001 0000c350 bf9d0e04
Call Trace:
[<c023363c ] hrtimer_start_range_ns+0x105/0x111
[<c051be99 ] do_nanosleep+0x54/0x8c
[<c02336d7 ] hrtimer_nanosleep+0x8f/0xee
[<c02332b8 ] hrtimer_wakeup+0x0/0x18
[<c051be7f ] do_nanosleep+0x3a/0x8c
[<c0233777 ] sys_nanosleep+0x41/0x51
[<c0202ce5 ] sysenter_do_call+0x12/0x25
ptree2 ? f6bee040 0 10466 10465
f638cb80 00000046 00200200 f6bee040 f6bee1ac c2b17260 f6bee038 0000dd77
00000000 c022f576 ffffffff 00000303 00000000 00000001 00000000 00000012
f5a61e84 f6bee040 f6bee038 c0224c29 f6270a90 00000001 f6bee038 f5a61f88
Call Trace:
[<c022f576 ] wakeme_after_rcu+0x0/0x8
[<c0224c29 ] do_exit+0x638/0x63c
[<c0224c87 ] do_group_exit+0x5a/0x83
[<c0224cbd ] sys_exit_group+0xd/0x10
[<c0202ce5 ] sysenter_do_call+0x12/0x25
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