Messages in this thread Patch in this message | | | From | Vitaly Kuznetsov <> | Subject | [PATCH 1/2] Drivers: hv: hv_balloon: correctly handle val.freeram<num_pages case | Date | Fri, 27 Mar 2015 17:02:59 +0100 |
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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> --- drivers/hv/hv_balloon.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/hv/hv_balloon.c b/drivers/hv/hv_balloon.c index d8c5802..20bfe36 100644 --- a/drivers/hv/hv_balloon.c +++ b/drivers/hv/hv_balloon.c @@ -1145,7 +1145,7 @@ 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; } -- 1.9.3
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