KY Srinivasan <kys@xxxxxxxxxxxxx> writes: >> -----Original Message----- >> From: Vitaly Kuznetsov [mailto:vkuznets@xxxxxxxxxx] >> Sent: Thursday, February 19, 2015 8:27 AM >> To: KY Srinivasan; devel@xxxxxxxxxxxxxxxxxxxxxx >> Cc: Haiyang Zhang; linux-kernel@xxxxxxxxxxxxxxx; Dexuan Cui >> Subject: [PATCH 1/2] Drivers: hv: hv_balloon: report offline pages as being >> used >> >> When hot-added memory pages are not brought online or when some >> memory blocks >> are sent offline the subsequent ballooning process kills the guest with OOM >> killer. This happens as we don't report these pages as neither used nor free >> and apparently host algorythm considers them as being unused. Keep track >> of >> all online/offline operations and report all currently offline pages as being >> used so host won't try to balloon them out. >> >> Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> >> --- >> drivers/hv/hv_balloon.c | 33 ++++++++++++++++++++++++--------- >> 1 file changed, 24 insertions(+), 9 deletions(-) >> >> diff --git a/drivers/hv/hv_balloon.c b/drivers/hv/hv_balloon.c >> index a095b70..e4b4454 100644 >> --- a/drivers/hv/hv_balloon.c >> +++ b/drivers/hv/hv_balloon.c >> @@ -503,6 +503,8 @@ struct hv_dynmem_device { >> * Number of pages we have currently ballooned out. >> */ >> unsigned int num_pages_ballooned; >> + unsigned int num_pages_onlined; >> + unsigned int num_pages_added; >> >> /* >> * State to manage the ballooning (up) operation. >> @@ -556,12 +558,15 @@ static void post_status(struct hv_dynmem_device >> *dm); >> static int hv_memory_notifier(struct notifier_block *nb, unsigned long val, >> void *v) >> { >> + struct memory_notify *mem = (struct memory_notify *)v; >> + >> switch (val) { >> case MEM_GOING_ONLINE: >> mutex_lock(&dm_device.ha_region_mutex); >> break; >> >> case MEM_ONLINE: >> + dm_device.num_pages_onlined += mem->nr_pages; >> case MEM_CANCEL_ONLINE: > > Why are we not adjusting num_pages_onlined when we cancel the online > Operation. Because we didn't increase the number yet. To my understanding, events come in the following order: 1) MEM_GOING_ONLINE - we just take the lock 2) MEM_ONLINE - and we increase nr_pages and drop the lock or MEM_CANCEL_ONLINE - we just drop the lock (mem never was online so nr_pages wasn't increased) 3) MEM_GOING_OFFLINE - we do nothing 4) MEM_OFFLINE - and we decrease nr_pages or MEM_CANCEL_OFFLINE - we do nothing (mem is still online, no need to adjust nr_pages) > > K. Y -- Vitaly _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
