kernel.git/drivers/xen/tmem.c, branch linux-4.1.y

cleancache: forbid overriding cleancache_ops

2015-04-14T23:49:03Z

Currently, cleancache_register_ops returns the previous value of cleancache_ops to allow chaining. However, chaining, as it is implemented now, is extremely dangerous due to possible pool id collisions. Suppose, a new cleancache driver is registered after the previous one assigned an id to a super block. If the new driver assigns the same id to another super block, which is perfectly possible, we will have two different filesystems using the same id. No matter if the new driver implements chaining or not, we are likely to get data corruption with such a configuration eventually. This patch therefore disables the ability to override cleancache_ops altogether as potentially dangerous. If there is already cleancache driver registered, all further calls to cleancache_register_ops will return EBUSY. Since no user of cleancache implements chaining, we only need to make minor changes to the code outside the cleancache core. Signed-off-by: Vladimir Davydov Cc: Konrad Rzeszutek Wilk Cc: Boris Ostrovsky Cc: David Vrabel Cc: Mark Fasheh Cc: Joel Becker Cc: Stefan Hengelein Cc: Florian Schmaus Cc: Andor Daam Cc: Dan Magenheimer Cc: Bob Liu Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

xen/tmem: mark xen_tmem_init() __init

2015-01-23T11:55:24Z

As a module_init() function, this should have been this way from the beginning. Signed-off-by: Jan Beulich Signed-off-by: David Vrabel

Merge tag 'stable/for-linus-3.11-rc0-tag-two' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen

2013-07-03T20:12:42Z

Pull Xen bugfixes from Konrad Rzeszutek Wilk: - Fix memory leak when CPU hotplugging. - Compile bugs with various #ifdefs - Fix state changes in Xen PCI front not dealing well with new toolstack. - Cleanups in code (use pr_*, fix 80 characters splits, etc) - Long standing bug in double-reporting the steal time * tag 'stable/for-linus-3.11-rc0-tag-two' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen: xen/time: remove blocked time accounting from xen "clockchip" xen: Convert printks to pr_ xen: ifdef CONFIG_HIBERNATE_CALLBACKS xen_*_suspend xen/pcifront: Deal with toolstack missing 'XenbusStateClosing' state. xen/time: Free onlined per-cpu data structure if we want to online it again. xen/time: Check that the per_cpu data structure has data before freeing. xen/time: Don't leak interrupt name when offlining. xen/time: Encapsulate the struct clock_event_device in another structure. xen/spinlock: Don't leak interrupt name when offlining. xen/smp: Don't leak interrupt name when offlining. xen/smp: Set the per-cpu IRQ number to a valid default. xen/smp: Introduce a common structure to contain the IRQ name and interrupt line. xen/smp: Coalesce the free_irq calls in one function. xen-pciback: fix error return code in pcistub_irq_handler_switch()

xen: Convert printks to pr_

2013-06-28T15:19:58Z

Convert printks to pr_ (excludes printk(KERN_DEBUG...) to be more consistent throughout the xen subsystem. Add pr_fmt with KBUILD_MODNAME or "xen:" KBUILD_MODNAME Coalesce formats and add missing word spaces Add missing newlines Align arguments and reflow to 80 columns Remove DRV_NAME from formats as pr_fmt adds the same content This does change some of the prefixes of these messages but it also does make them more consistent. Signed-off-by: Joe Perches Signed-off-by: Konrad Rzeszutek Wilk

xen/tmem: Don't over-write tmem_frontswap_poolid after tmem_frontswap_init set it.

2013-06-10T14:14:33Z

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 Reviewed-by: Bob Liu

xmem/tmem: fix 'undefined variable' build error.

2013-05-28T13:54:48Z

In the (not so useful) kernel configuration where CONFIG_SWAP is undefined and CONFIG_XEN_SELFBALLOONING is defined, xen_tmem_init would use undefined variable 'static bool frontswap'. Added #else to have #define frontswap (0) in the case where CONFIG_FRONTSWAP is not defined. Signed-off-by: Frederico Cadete Signed-off-by: Konrad Rzeszutek Wilk

xen/tmem: Don't use self[ballooning|shrinking] if frontswap is off.

2013-05-15T14:27:50Z

There is no point. We would just squeeze the guest to put more and more pages in the swap disk without any purpose. The only time it makes sense to use the selfballooning and shrinking is when frontswap is being utilized. Signed-off-by: Konrad Rzeszutek Wilk

xen/tmem: Remove the boot options and fold them in the tmem.X parameters.

2013-05-15T14:27:47Z

If tmem is built-in or a module, the user has the option on the command line to influence it by doing: tmem. instead of having a variety of "nocleancache", and "nofrontswap". The others: "noselfballooning" and "selfballooning"; and "noselfshrink" are in a different driver xen-selfballoon.c and the patches: xen/tmem: Remove the usage of 'noselfshrink' and use 'tmem.selfshrink' bool instead. xen/tmem: Remove the usage of 'noselfballoon','selfballoon' and use 'tmem.selfballon' bool instead. remove them. Also add documentation. Signed-off-by: Konrad Rzeszutek Wilk

xen/tmem: s/disable_// and change the logic.

2013-05-15T14:27:46Z

The variety of disable_[cleancache|frontswap|selfshrinking] are making this a bit complex. Just remove the "disable_" part and change the logic around for the "nofrontswap" and "nocleancache" parameters. Signed-off-by: Konrad Rzeszutek Wilk

xen/tmem: Fix compile warning.

2013-05-15T14:27:45Z

We keep on getting: drivers/xen/tmem.c:65:13: warning: ‘disable_frontswap_selfshrinking’ defined but not used [-Wunused-variable] if CONFIG_FRONTSWAP=y and # CONFIG_CLEANCACHE is not set Found by 0 day test project Reported-by: Fengguang Wu Signed-off-by: Konrad Rzeszutek Wilk