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| author | Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> | 2013-06-07 15:26:03 -0400 |
|---|---|---|
| committer | Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> | 2013-06-10 10:14:33 -0400 |
| commit | b2c75c446ae72387916e2caf6e6dca815b6e5e6e (patch) | |
| tree | 5b97f2908fec2b03b6dfef5f52d5e79f2597f750 | |
| parent | 466318a87f28cb3ba0d08a3b7ef1a37ae73d5aa7 (diff) | |
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>
| -rw-r--r-- | drivers/xen/tmem.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/xen/tmem.c b/drivers/xen/tmem.c index cc072c66c76..0f0493c6337 100644 --- a/drivers/xen/tmem.c +++ b/drivers/xen/tmem.c @@ -379,10 +379,10 @@ static int xen_tmem_init(void) #ifdef CONFIG_FRONTSWAP if (tmem_enabled && frontswap) { char *s = ""; - struct frontswap_ops *old_ops = - frontswap_register_ops(&tmem_frontswap_ops); + struct frontswap_ops *old_ops; tmem_frontswap_poolid = -1; + old_ops = frontswap_register_ops(&tmem_frontswap_ops); if (IS_ERR(old_ops) || old_ops) { if (IS_ERR(old_ops)) return PTR_ERR(old_ops); |