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Input: xen-kbdfront - free grant table entry in xenkbd_disconnect_backend

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xenkbd_disconnect_backend doesn't free grant table entry.  This bug affects
live migration.

xenkbd_disconnect_backend uses gnttab_end_foreign_access_ref to handle
grant table entry which doesn't really free an entry.

Thus every time we do xenkbd_resume, grant table entry increses by one. As
an grant table entry occupies 8 bytes, an grant table page has at most 512
entries. Every 512 times we do xenkdb_resume, grant table pages increses by
one.

After around 3500 times of live migration, grant table pages will increase
by 7, causing too many pages to populate and hitting max_pages limit when
assigning pages.Thus assign_pages will fail, so will live migration.

Signed-off-by: Chang Huaixin <huaixin.chx@alibaba-inc.com>
Acked-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
This commit is contained in:
Chang Huaixin 2014-10-16 13:33:24 -07:00 committed by Dmitry Torokhov
parent b0cfb794a3
commit 4d544e3bdb
1 changed files with 2 additions and 2 deletions
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4
drivers/input/misc/xen-kbdfront.c
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@ -285,7 +285,7 @@ static int xenkbd_connect_backend(struct xenbus_device *dev,
error_evtchan:
xenbus_free_evtchn(dev, evtchn);
error_grant:
gnttab_end_foreign_access_ref(info->gref, 0);
gnttab_end_foreign_access(info->gref, 0, 0UL);
info->gref = -1;
return ret;
}
@ -296,7 +296,7 @@ static void xenkbd_disconnect_backend(struct xenkbd_info *info)
unbind_from_irqhandler(info->irq, info);
info->irq = -1;
if (info->gref >= 0)
gnttab_end_foreign_access_ref(info->gref, 0);
gnttab_end_foreign_access(info->gref, 0, 0UL);
info->gref = -1;
}