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Drivers: hv: hv_balloon: correctly handle val.freeram<num_pages case

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'Drivers: hv: hv_balloon: refuse to balloon below the floor' fix does not
correctly handle the case when val.freeram < num_pages as val.freeram is
__kernel_ulong_t and the 'val.freeram - num_pages' value will be a huge
positive value instead of being negative.

Usually host doesn't ask us to balloon more than val.freeram but in case
he have a memory hog started after we post the last pressure report we
can get into troubles.

Suggested-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Vitaly Kuznetsov 2015-03-31 11:16:40 -07:00 committed by Greg Kroah-Hartman
parent 6a84d63d22
commit ba0c444153
1 changed files with 1 additions and 1 deletions
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2
drivers/hv/hv_balloon.c
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@ -1155,7 +1155,7 @@ static void balloon_up(struct work_struct *dummy)
floor = compute_balloon_floor();
/* Refuse to balloon below the floor, keep the 2M granularity. */
if (val.freeram - num_pages < floor) {
if (val.freeram < num_pages || val.freeram - num_pages < floor) {
num_pages = val.freeram > floor ? (val.freeram - floor) : 0;
num_pages -= num_pages % PAGES_IN_2M;
}