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Date: Tue, 31 Mar 2015 11:16:40 -0700 From: "K. Y. Srinivasan" <kys@...rosoft.com> To: gregkh@...uxfoundation.org, linux-kernel@...r.kernel.org, devel@...uxdriverproject.org, olaf@...fle.de, apw@...onical.com, vkuznets@...hat.com, jasowang@...hat.com Cc: "K. Y. Srinivasan" <kys@...rosoft.com> Subject: [PATCH 1/2] Drivers: hv: hv_balloon: correctly handle val.freeram<num_pages case From: Vitaly Kuznetsov <vkuznets@...hat.com> '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@...hat.com> Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com> Reviewed-by: Laszlo Ersek <lersek@...hat.com> Signed-off-by: K. Y. Srinivasan <kys@...rosoft.com> --- drivers/hv/hv_balloon.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/drivers/hv/hv_balloon.c b/drivers/hv/hv_balloon.c index 74312c8..4052ad8 100644 --- a/drivers/hv/hv_balloon.c +++ b/drivers/hv/hv_balloon.c @@ -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; } -- 1.7.4.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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