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Subject[PATCH] xen: tmem: selfballooning should be enabled when xen tmem is enabled
Konrad: Any chance this can get in for the upcoming window?
(Or is it enough of a bug fix that it can go in at an -rcN?)

It was just pointed out to me that some kernels have
cleancache and frontswap and xen_tmem enabled but NOT
xen_selfballooning! While this configuration should be
possible, nearly all kernels that have CONFIG_XEN_TMEM=y should
also have CONFIG_XEN_SELFBALLOONING=y, since Transcendent
Memory (tmem) for Xen has very limited value without
selfballooning.

This is probably a result of a Kconfig mistake fixed I think
by the patch below. Note that the year-old Oracle UEK2 kernel
distro has both CONFIG_XEN_TMEM and CONFIG_XEN_SELFBALLOONING
enabled, as does a Fedora 17 kernel update (3.6.6-1.fc17), so
the combination should be well tested. Also, Xen tmem (and thus
selfballooning) are currently only enabled when a kernel boot
parameter is supplied so there is no runtime impact without
that boot parameter.

Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com>

diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig
index d4dffcd..b5f02f3 100644
--- a/drivers/xen/Kconfig
+++ b/drivers/xen/Kconfig
@@ -10,9 +10,9 @@ config XEN_BALLOON
return unneeded memory to the system.

config XEN_SELFBALLOONING
- bool "Dynamically self-balloon kernel memory to target"
- depends on XEN && XEN_BALLOON && CLEANCACHE && SWAP && XEN_TMEM
- default n
+ bool
+ depends on XEN_BALLOON && SWAP
+ default y if XEN_TMEM
help
Self-ballooning dynamically balloons available kernel memory driven
by the current usage of anonymous memory ("committed AS") and

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