Re: [Xen-devel] pv guests die after failed migration

[Andreas Olsowski <andreas.olsowski@xxxxxxxxxxx>]

On 09/23/2011 09:47 AM, Ian Campbell wrote:
> This seems to be taking the non-cancelled resume path, does this patch
> help at all:
>
> diff -r d7b14b76f1eb tools/libxl/libxl.c
> --- a/tools/libxl/libxl.c       Thu Sep 22 14:26:08 2011 +0100
> +++ b/tools/libxl/libxl.c       Fri Sep 23 08:45:28 2011 +0100
> @@ -246,7 +246,7 @@ int libxl_domain_resume(libxl_ctx *ctx,
>           rc = ERROR_NI;
>           goto out;
>       }
> -    if (xc_domain_resume(ctx->xch, domid, 0)) {
> +    if (xc_domain_resume(ctx->xch, domid, 1)) {
>           LIBXL__LOG_ERRNO(ctx, LIBXL__LOG_ERROR,
>                           "xc_domain_resume failed for domain %u",
>                           domid);
>
> I don't think that's a solution but if this patch works then it may
> indicate a problem with xc_domain_resume_any.
For the curent xen-4.1-testing.hg the patch had to be modified to a 
different position:
--- a/tools/libxl/libxl.c  Thu Sep 22 14:26:08 2011 +0100
+++ b/tools/libxl/libxl.c  Fri Sep 23 08:45:28 2011 +0100
@@ -229,7 +229,7 @@
         rc = ERROR_NI;
         goto out;
     }
-    if (xc_domain_resume(ctx->xch, domid, 0)) {
+    if (xc_domain_resume(ctx->xch, domid, 1)) {
         LIBXL__LOG_ERRNO(ctx, LIBXL__LOG_ERROR,
                         "xc_domain_resume failed for domain %u",
                         domid);


I did a clean/make/install after that, compilation worked fine.

I then tested the migration towards an unsuitable target again and it 
did what you thought it could do. The guest resumes correctly at sender
###############
root@xenturio1:~# xl -vvv migrate thishopefullywontfail xenturio2
Saving to migration stream new xl format (info 0x0/0x0/407)
migration target: Ready to receive domain.
Loading new save file incoming migration stream (new xl fmt info 
0x0/0x0/407)
 Savefile contains xl domain config
xc: detail: Had 0 unexplained entries in p2m table
xc: Saving memory: iter 0 (last sent 0 skipped 0): 133120/133120  100%
xc: detail: delta 9529ms, dom0 93%, target 1%, sent 449Mb/s, dirtied 
1Mb/s 502 pages
xc: Saving memory: iter 1 (last sent 130592 skipped 480): 133120/133120 
 100%
xc: detail: delta 37ms, dom0 91%, target 2%, sent 444Mb/s, dirtied 
30Mb/s 34 pages
xc: Saving memory: iter 2 (last sent 502 skipped 0): 133120/133120  100% 

xc: detail: Start last iteration
libxl: debug: libxl_dom.c:384:libxl__domain_suspend_common_callback 
issuing PV suspend request via XenBus control node
libxl: debug: libxl_dom.c:389:libxl__domain_suspend_common_callback wait 
for the guest to acknowledge suspend request
libxl: debug: libxl_dom.c:434:libxl__domain_suspend_common_callback 
guest acknowledged suspend request
libxl: debug: libxl_dom.c:438:libxl__domain_suspend_common_callback wait 
for the guest to suspend
libxl: debug: libxl_dom.c:450:libxl__domain_suspend_common_callback 
guest has suspended
xc: detail: SUSPEND shinfo 0007fafc
xc: detail: delta 204ms, dom0 3%, target 0%, sent 4Mb/s, dirtied 25Mb/s 
156 pages
xc: Saving memory: iter 3 (last sent 30 skipped 4): 133120/133120  100%
xc: detail: delta 3ms, dom0 0%, target 0%, sent 1703Mb/s, dirtied 
1703Mb/s 156 pages
xc: detail: Total pages sent= 131280 (0.99x)
xc: detail: (of which 0 were fixups)
xc: detail: All memory is saved
xc: detail: Save exit rc=0
libxl: error: libxl.c:900:validate_virtual_disk failed to stat 
/dev/xen-data/thishopefullywontfail-root: No such file or directory
cannot add disk 0 to domain: -6
migration target: Domain creation failed (code -3).
libxl: error: libxl_utils.c:408:libxl_read_exactly file/stream truncated 
reading ready message from migration receiver stream
libxl: info: libxl_exec.c:72:libxl_report_child_exitstatus migration 
target process [16608] exited with error status 3
Migration failed, resuming at sender.


root@xenturio1:~# xl console thishopefullywontfail
PM: freeze of devices complete after 0.197 msecs
PM: late freeze of devices complete after 0.067 msecs
PM: early thaw of devices complete after 0.074 msecs
PM: thaw of devices complete after 0.077 msecs

root@thishopefullywontfail:~#
#####################

So that works


There is no mention of the migration failing in the guest log though, 
maybe when a final patch is made it should log that failing migration?


with best regards



andreas

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