Konrad Rzeszutek Wilk b2c75c446a xen/tmem: Don't over-write tmem_frontswap_poolid after tmem_frontswap_init set it.
Commit 10a7a0771399a57a297fca9615450dbb3f88081a ("xen: tmem: enable Xen
tmem shim to be built/loaded as a module") allows the tmem module
to be loaded any time. For this work the frontswap API had to
be able to asynchronously to call tmem_frontswap_init before
or after the swap image had been set. That was added in git
commit 905cd0e1bf9ffe82d6906a01fd974ea0f70be97a
("mm: frontswap: lazy initialization to allow tmem backends to build/run as modules").

Which means we could do this (The common case):

 modprobe tmem		[so calls frontswap_register_ops, no ->init]
			 modifies tmem_frontswap_poolid = -1
 swapon /dev/xvda1	[__frontswap_init, calls -> init, tmem_frontswap_poolid is
			 < 0 so tmem hypercall done]

Or the failing one:

 swapon /dev/xvda1	[calls __frontswap_init, sets the need_init bitmap]
 modprobe tmem		[calls frontswap_register_ops, -->init calls, finds out
			tmem_frontswap_poolid is 0, does not make a hypercall.
			Later in the module_init, sets tmem_frontswap_poolid=-1]

Which meant that in the failing case we would not call the hypercall
to initialize the pool and never be able to make any frontswap
backend calls.

Moving the frontswap_register_ops after setting the tmem_frontswap_poolid
fixes it.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: Bob Liu <bob.liu@oracle.com>
2013-06-10 10:14:33 -04:00
..
2013-05-09 16:33:42 -07:00
2013-05-07 11:22:14 -07:00
2013-05-07 20:16:25 -07:00
2013-04-29 00:08:46 +02:00
2013-04-26 22:30:25 +02:00
2013-05-09 10:11:08 -07:00
2013-05-09 09:59:16 -07:00
2013-05-09 09:59:16 -07:00
2013-05-06 13:07:33 +02:00
2013-05-09 09:59:16 -07:00
2013-05-09 09:59:16 -07:00
2013-05-06 14:59:13 -07:00
2013-05-09 09:59:16 -07:00
2013-05-10 14:37:21 +01:00
2013-04-16 00:39:41 +02:00
2013-05-09 10:21:44 -07:00
2013-05-09 09:59:16 -07:00
2013-05-07 14:04:56 -07:00
2013-05-07 14:02:00 -07:00
2013-05-09 09:59:16 -07:00
2013-05-09 09:59:16 -07:00
2013-05-02 14:02:32 -07:00
2013-05-07 10:13:52 -07:00
2013-05-09 09:59:16 -07:00
2013-05-04 12:31:18 -07:00
2013-05-04 12:31:18 -07:00