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authorDavid Hildenbrand <david@redhat.com>2020-04-07 06:07:32 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2020-04-07 20:43:40 +0300
commitbc58ebd506c369c26337cf6b1a400af1a25c989c (patch)
tree4e5c7e1dc60f66276c96518ecfb7e1fa65a99caa /drivers/hv
parented7f9fec8c8f8227ebd1fb69feda60ce4a7df61f (diff)
downloadlinux-bc58ebd506c369c26337cf6b1a400af1a25c989c.tar.xz
hv_balloon: don't check for memhp_auto_online manually
We get the MEM_ONLINE notifier call if memory is added right from the kernel via add_memory() or later from user space. Let's get rid of the "ha_waiting" flag - the wait event has an inbuilt mechanism (->done) for that. Initialize the wait event only once and reinitialize before adding memory. Unconditionally call complete() and wait_for_completion_timeout(). If there are no waiters, complete() will only increment ->done - which will be reset by reinit_completion(). If complete() has already been called, wait_for_completion_timeout() will not wait. There is still the chance for a small race between concurrent reinit_completion() and complete(). If complete() wins, we would not wait - which is tolerable (and the race exists in current code as well). Note: We only wait for "some" memory to get onlined, which seems to be good enough for now. [akpm@linux-foundation.org: register_memory_notifier() after init_completion(), per David] Signed-off-by: David Hildenbrand <david@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com> Reviewed-by: Baoquan He <bhe@redhat.com> Cc: "K. Y. Srinivasan" <kys@microsoft.com> Cc: Haiyang Zhang <haiyangz@microsoft.com> Cc: Stephen Hemminger <sthemmin@microsoft.com> Cc: Wei Liu <wei.liu@kernel.org> Cc: Oscar Salvador <osalvador@suse.de> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Cc: Wei Yang <richard.weiyang@gmail.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Eduardo Habkost <ehabkost@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Igor Mammedov <imammedo@redhat.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Paul Mackerras <paulus@samba.org> Cc: Yumei Huang <yuhuang@redhat.com> Link: http://lkml.kernel.org/r/20200317104942.11178-6-david@redhat.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/hv')
-rw-r--r--drivers/hv/hv_balloon.c25
1 files changed, 10 insertions, 15 deletions
diff --git a/drivers/hv/hv_balloon.c b/drivers/hv/hv_balloon.c
index a02ce43d778d..32e3bc0aa665 100644
--- a/drivers/hv/hv_balloon.c
+++ b/drivers/hv/hv_balloon.c
@@ -533,7 +533,6 @@ struct hv_dynmem_device {
* State to synchronize hot-add.
*/
struct completion ol_waitevent;
- bool ha_waiting;
/*
* This thread handles hot-add
* requests from the host as well as notifying
@@ -634,10 +633,7 @@ static int hv_memory_notifier(struct notifier_block *nb, unsigned long val,
switch (val) {
case MEM_ONLINE:
case MEM_CANCEL_ONLINE:
- if (dm_device.ha_waiting) {
- dm_device.ha_waiting = false;
- complete(&dm_device.ol_waitevent);
- }
+ complete(&dm_device.ol_waitevent);
break;
case MEM_OFFLINE:
@@ -726,8 +722,7 @@ static void hv_mem_hot_add(unsigned long start, unsigned long size,
has->covered_end_pfn += processed_pfn;
spin_unlock_irqrestore(&dm_device.ha_lock, flags);
- init_completion(&dm_device.ol_waitevent);
- dm_device.ha_waiting = !memhp_auto_online;
+ reinit_completion(&dm_device.ol_waitevent);
nid = memory_add_physaddr_to_nid(PFN_PHYS(start_pfn));
ret = add_memory(nid, PFN_PHYS((start_pfn)),
@@ -753,15 +748,14 @@ static void hv_mem_hot_add(unsigned long start, unsigned long size,
}
/*
- * Wait for the memory block to be onlined when memory onlining
- * is done outside of kernel (memhp_auto_online). Since the hot
- * add has succeeded, it is ok to proceed even if the pages in
- * the hot added region have not been "onlined" within the
- * allowed time.
+ * Wait for memory to get onlined. If the kernel onlined the
+ * memory when adding it, this will return directly. Otherwise,
+ * it will wait for user space to online the memory. This helps
+ * to avoid adding memory faster than it is getting onlined. As
+ * adding succeeded, it is ok to proceed even if the memory was
+ * not onlined in time.
*/
- if (dm_device.ha_waiting)
- wait_for_completion_timeout(&dm_device.ol_waitevent,
- 5*HZ);
+ wait_for_completion_timeout(&dm_device.ol_waitevent, 5 * HZ);
post_status(&dm_device);
}
}
@@ -1706,6 +1700,7 @@ static int balloon_probe(struct hv_device *dev,
#ifdef CONFIG_MEMORY_HOTPLUG
set_online_page_callback(&hv_online_page);
+ init_completion(&dm_device.ol_waitevent);
register_memory_notifier(&hv_memory_nb);
#endif