From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D15B0C433FE for ; Tue, 5 Oct 2021 13:34:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B691061207 for ; Tue, 5 Oct 2021 13:34:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235068AbhJENg3 (ORCPT ); Tue, 5 Oct 2021 09:36:29 -0400 Received: from smtp-out2.suse.de ([195.135.220.29]:41132 "EHLO smtp-out2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234103AbhJENg1 (ORCPT ); Tue, 5 Oct 2021 09:36:27 -0400 Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id 9BBDF20028; Tue, 5 Oct 2021 13:34:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1633440875; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=muVpN94mowz5PNDdbHLdWMwCxQCzzIFQLh6tPGkXOCw=; b=WB084CpVgo7IVkufWcK3GX0mN37NTIXQAwwmpfy8mfvZjcDCTnJJph90jEaoPJ8gs6E5BO s7Z+YiKqhftnBIOnEtwSjw6L/5HUFyKN3dBids+HBSzO8WlZAQPyLKQ8bJBkW6WBWRx9Qa iO4ZxJ64g3GTX589cF6hqBGZ96qyPzc= Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 6487D13C35; Tue, 5 Oct 2021 13:34:35 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id a1xEF2tUXGHnDwAAMHmgww (envelope-from ); Tue, 05 Oct 2021 13:34:35 +0000 From: Juergen Gross To: xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org Cc: Juergen Gross , Boris Ostrovsky , Stefano Stabellini , stable@vger.kernel.org, =?UTF-8?q?Marek=20Marczykowski-G=C3=B3recki?= Subject: [PATCH] xen/balloon: fix cancelled balloon action Date: Tue, 5 Oct 2021 15:34:33 +0200 Message-Id: <20211005133433.32008-1-jgross@suse.com> X-Mailer: git-send-email 2.26.2 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In case a ballooning action is cancelled the new kernel thread handling the ballooning might end up in a busy loop. Fix that by handling the cancelled action gracefully. While at it introduce a short wait for the BP_WAIT case. Cc: stable@vger.kernel.org Fixes: 8480ed9c2bbd56 ("xen/balloon: use a kernel thread instead a workqueue") Reported-by: Marek Marczykowski-Górecki Signed-off-by: Juergen Gross --- drivers/xen/balloon.c | 21 +++++++++++++++------ 1 file changed, 15 insertions(+), 6 deletions(-) diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c index 43ebfe36ac27..3a50f097ed3e 100644 --- a/drivers/xen/balloon.c +++ b/drivers/xen/balloon.c @@ -491,12 +491,12 @@ static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp) } /* - * Stop waiting if either state is not BP_EAGAIN and ballooning action is - * needed, or if the credit has changed while state is BP_EAGAIN. + * Stop waiting if either state is BP_DONE and ballooning action is + * needed, or if the credit has changed while state is not BP_DONE. */ static bool balloon_thread_cond(enum bp_state state, long credit) { - if (state != BP_EAGAIN) + if (state == BP_DONE) credit = 0; return current_credit() != credit || kthread_should_stop(); @@ -516,10 +516,19 @@ static int balloon_thread(void *unused) set_freezable(); for (;;) { - if (state == BP_EAGAIN) - timeout = balloon_stats.schedule_delay * HZ; - else + switch (state) { + case BP_DONE: + case BP_ECANCELED: timeout = 3600 * HZ; + break; + case BP_EAGAIN: + timeout = balloon_stats.schedule_delay * HZ; + break; + case BP_WAIT: + timeout = HZ; + break; + } + credit = current_credit(); wait_event_freezable_timeout(balloon_thread_wq, -- 2.26.2