libxc: after saving, unmap correct amount for live_m2p

With some help from Olaf, I've finally got to the bottom of an issue I
came across while trying to implement save/restore in the libvirt
libxenlight driver.  After issuing the save operation, the saved domain
was not being cleaned up properly and left in this state from xl's
perspective

xen33:# xl list
Name                   ID   Mem VCPUs      State   Time(s)
Domain-0                0  6821     8     r-----     122.5
(null)                  2     2     2     --pssd      10.8

Checking the libvirtd /proc/$pid/maps I found this

7f3798984000-7f3798b86000 r--s 00002000 00:03 4026532097 /proc/xen/privcmd

So not all all pages belonging to the domain were unmapped from
libvirtd.  In tools/libxc/xc_domain_save.c we found that P2M_FL_ENTRIES
were being mapped but only P2M_FLL_ENTRIES were being unmapped.  The
attached patch changes the unmapping to use the same P2M_FL_ENTRIES
macro.  I'm not too familiar with this code though so posting here for
review.

I suspect this was not noticed before since most (all?) processes doing
save terminate after the save and are not long-running like libvirtd.

Ian Campbell writes:
> Looks like I introduced this in 18558:ccf0205255e1, sorry!
>
> I guess it is also wrong in the error path out of map_and_save_p2m_table
> and so we also need [another hunk].

This change should be backported to relevant earlier trees. -iwj

From: Jim Fehlig <jfehlig@novell.com>
From: Ian Campbell <Ian.Campbell@citrix.com>
Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>
Cc: Olaf Hering <olaf@aepfle.de>
Acked-by: Ian Campbell <Ian.Campbell@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Committed-by: Ian Jackson <ian.jackson@eu.citrix.com>

diff --git a/tools/libxc/xc_domain_save.c b/tools/libxc/xc_domain_save.c
index fa270f51f6dbc095bc909b0569b48eb83e8e3ab4..4deca18a16eff615c5eba15398fa746695d6d60b 100644 (file)
--- a/tools/libxc/xc_domain_save.c
+++ b/tools/libxc/xc_domain_save.c
@@ -861,7 +861,7 @@ static xen_pfn_t *map_and_save_p2m_table(xc_interface *xch,
  out:
     
     if ( !success && p2m )
-        munmap(p2m, P2M_FLL_ENTRIES * PAGE_SIZE);
+        munmap(p2m, P2M_FL_ENTRIES * PAGE_SIZE);
 
     if ( live_p2m_frame_list_list )
         munmap(live_p2m_frame_list_list, PAGE_SIZE);
@@ -1955,7 +1955,7 @@ int xc_domain_save(xc_interface *xch, int io_fd, uint32_t dom, uint32_t max_iter
         munmap(live_shinfo, PAGE_SIZE);
 
     if ( ctx->live_p2m )
-        munmap(ctx->live_p2m, P2M_FLL_ENTRIES * PAGE_SIZE);
+        munmap(ctx->live_p2m, P2M_FL_ENTRIES * PAGE_SIZE);
 
     if ( ctx->live_m2p )
         munmap(ctx->live_m2p, M2P_SIZE(ctx->max_mfn));