kernel/linux.git/drivers/xen/balloon.c, branch v6.4

xen: simplify sysctl registration for balloon

2023-04-13T18:49:20+00:00

register_sysctl_table() is a deprecated compatibility wrapper. register_sysctl_init() can do the directory creation for you so just use that. Signed-off-by: Luis Chamberlain Reviewed-by: Juergen Gross

xen/balloon: don't use PV mode extra memory for zone device allocations

2022-04-07T20:08:37+00:00

When running as a Xen PV guest use the extra memory (memory which isn't allocated for the guest at boot time) only for ballooning purposes and not for zone device allocations. This will remove some code without any lack of functionality. While at it move some code to get rid of another #ifdef. Remove a comment which is stale since some time now. Signed-off-by: Juergen Gross Link: https://lore.kernel.org/r/20220407093857.1485-1-jgross@suse.com Reviewed-by: Boris Ostrovsky Signed-off-by: Boris Ostrovsky

xen: use time_is_before_eq_jiffies() instead of open coding it

2022-03-10T15:27:55+00:00

Use the helper function time_is_{before,after}_jiffies() to improve code readability. Signed-off-by: Wang Qing Reviewed-by: Boris Ostrovsky Link: https://lore.kernel.org/r/1646018104-61415-1-git-send-email-wangqing@vivo.com Signed-off-by: Boris Ostrovsky

xen/balloon: Bring alloc(free)_xenballooned_pages helpers back

2022-01-06T08:53:35+00:00

This patch rolls back some of the changes introduced by commit 121f2faca2c0a "xen/balloon: rename alloc/free_xenballooned_pages" in order to make possible to still allocate xenballooned pages if CONFIG_XEN_UNPOPULATED_ALLOC is enabled. On Arm the unpopulated pages will be allocated on top of extended regions provided by Xen via device-tree (the subsequent patches will add required bits to support unpopulated-alloc feature on Arm). The problem is that extended regions feature has been introduced into Xen quite recently (during 4.16 release cycle). So this effectively means that Linux must only use unpopulated-alloc on Arm if it is running on "new Xen" which advertises these regions. But, it will only be known after parsing the "hypervisor" node at boot time, so before doing that we cannot assume anything. In order to keep working if CONFIG_XEN_UNPOPULATED_ALLOC is enabled and the extended regions are not advertised (Linux is running on "old Xen", etc) we need the fallback to alloc_xenballooned_pages(). This way we wouldn't reduce the amount of memory usable (wasting RAM pages) for any of the external mappings anymore (and eliminate XSA-300) with "new Xen", but would be still functional ballooning out RAM pages with "old Xen". Also rename alloc(free)_xenballooned_pages to xen_alloc(free)_ballooned_pages and make xen_alloc(free)_unpopulated_pages static inline in xen.h if CONFIG_XEN_UNPOPULATED_ALLOC is disabled. Signed-off-by: Oleksandr Tyshchenko Reviewed-by: Stefano Stabellini Link: https://lore.kernel.org/r/1639080336-26573-4-git-send-email-olekstysh@gmail.com Signed-off-by: Juergen Gross

xen/balloon: fix unused-variable warning

2021-11-08T16:40:17+00:00

In configurations with CONFIG_XEN_BALLOON_MEMORY_HOTPLUG=n and CONFIG_XEN_BALLOON_MEMORY_HOTPLUG=y, gcc warns about an unused variable: drivers/xen/balloon.c:83:12: error: 'xen_hotplug_unpopulated' defined but not used [-Werror=unused-variable] Since this is always zero when CONFIG_XEN_BALLOON_MEMORY_HOTPLUG is disabled, turn it into a preprocessor constant in that case. Fixes: 121f2faca2c0 ("xen/balloon: rename alloc/free_xenballooned_pages") Signed-off-by: Arnd Bergmann Link: https://lore.kernel.org/r/20211108111408.3940366-1-arnd@kernel.org Reviewed-by: Juergen Gross Signed-off-by: Boris Ostrovsky

xen/balloon: rename alloc/free_xenballooned_pages

2021-11-04T17:59:44+00:00

alloc_xenballooned_pages() and free_xenballooned_pages() are used as direct replacements of xen_alloc_unpopulated_pages() and xen_free_unpopulated_pages() in case CONFIG_XEN_UNPOPULATED_ALLOC isn't defined. Guard both functions with !CONFIG_XEN_UNPOPULATED_ALLOC and rename them to the xen_*() variants they are replacing. This allows to remove some ifdeffery from the xen.h header file. Adapt the prototype of the functions to match. Signed-off-by: Juergen Gross Link: https://lore.kernel.org/r/20211102092234.17852-1-jgross@suse.com Reviewed-by: Boris Ostrovsky Signed-off-by: Boris Ostrovsky

xen/balloon: add late_initcall_sync() for initial ballooning done

2021-11-04T17:59:17+00:00

When running as PVH or HVM guest with actual memory < max memory the hypervisor is using "populate on demand" in order to allow the guest to balloon down from its maximum memory size. For this to work correctly the guest must not touch more memory pages than its target memory size as otherwise the PoD cache will be exhausted and the guest is crashed as a result of that. In extreme cases ballooning down might not be finished today before the init process is started, which can consume lots of memory. In order to avoid random boot crashes in such cases, add a late init call to wait for ballooning down having finished for PVH/HVM guests. Warn on console if initial ballooning fails, panic() after stalling for more than 3 minutes per default. Add a module parameter for changing this timeout. [boris: replaced pr_info() with pr_notice()] Cc: Reported-by: Marek Marczykowski-Górecki Signed-off-by: Juergen Gross Link: https://lore.kernel.org/r/20211102091944.17487-1-jgross@suse.com Reviewed-by: Boris Ostrovsky Signed-off-by: Boris Ostrovsky

xen/balloon: fix cancelled balloon action

2021-10-06T05:45:00+00:00

In case a ballooning action is cancelled the new kernel thread handling the ballooning might end up in a busy loop. Fix that by handling the cancelled action gracefully. While at it introduce a short wait for the BP_WAIT case. Cc: stable@vger.kernel.org Fixes: 8480ed9c2bbd56 ("xen/balloon: use a kernel thread instead a workqueue") Reported-by: Marek Marczykowski-Górecki Signed-off-by: Juergen Gross Tested-by: Jason Andryuk Reviewed-by: Boris Ostrovsky Link: https://lore.kernel.org/r/20211005133433.32008-1-jgross@suse.com Signed-off-by: Juergen Gross

xen/balloon: fix balloon kthread freezing

2021-09-21T07:39:04+00:00

Commit 8480ed9c2bbd56 ("xen/balloon: use a kernel thread instead a workqueue") switched the Xen balloon driver to use a kernel thread. Unfortunately the patch omitted to call try_to_freeze() or to use wait_event_freezable_timeout(), causing a system suspend to fail. Fixes: 8480ed9c2bbd56 ("xen/balloon: use a kernel thread instead a workqueue") Signed-off-by: Juergen Gross Reviewed-by: Boris Ostrovsky Link: https://lore.kernel.org/r/20210920100345.21939-1-jgross@suse.com Signed-off-by: Juergen Gross

xen/balloon: use a kernel thread instead a workqueue

2021-09-14T07:53:48+00:00

Today the Xen ballooning is done via delayed work in a workqueue. This might result in workqueue hangups being reported in case of large amounts of memory are being ballooned in one go (here 16GB): BUG: workqueue lockup - pool cpus=6 node=0 flags=0x0 nice=0 stuck for 64s! Showing busy workqueues and worker pools: workqueue events: flags=0x0 pwq 12: cpus=6 node=0 flags=0x0 nice=0 active=2/256 refcnt=3 in-flight: 229:balloon_process pending: cache_reap workqueue events_freezable_power_: flags=0x84 pwq 12: cpus=6 node=0 flags=0x0 nice=0 active=1/256 refcnt=2 pending: disk_events_workfn workqueue mm_percpu_wq: flags=0x8 pwq 12: cpus=6 node=0 flags=0x0 nice=0 active=1/256 refcnt=2 pending: vmstat_update pool 12: cpus=6 node=0 flags=0x0 nice=0 hung=64s workers=3 idle: 2222 43 This can easily be avoided by using a dedicated kernel thread for doing the ballooning work. Reported-by: Jan Beulich Signed-off-by: Juergen Gross Reviewed-by: Boris Ostrovsky Link: https://lore.kernel.org/r/20210827123206.15429-1-jgross@suse.com Signed-off-by: Juergen Gross