From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 65F771E04B1; Fri, 4 Oct 2024 18:31:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728066674; cv=none; b=e/MLCXgrT1sSrejRlMdZUPbxl1UR9tJmvjCV+IEREUmPftfvdrlr+3zb95FEuj0fovyDE7MrD/X+DbaOZ/5o+0OosWjmiG69Qy7rfQuFgEgOfMI/RWbyQWTS2/Lm1ch9p/EBFJps1Z6Eogel90LTqJog2oJK7gTBKhZ2kTWm9Rg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728066674; c=relaxed/simple; bh=kvOXRNJdLSkFt19dQGORrV4xUn+I7ThF4IlOi+Fs/2k=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=SP/Ehorg7lyhfDm2Tz46cPVtIMv07TqIQtBTWTA+ZmM84b0aawmlecnse5UNdMwVlYAo/PIwDDnNuYlEXBTpNvp5bGK9oMwpPeT5d6eLTVqUH6qDWdmvwr6AxU6thmN4m+BBUkQmEIkpIy+mg+kmBdBcZPaJUvHTRA6FThJr9Kk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=D76lt81Z; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="D76lt81Z" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 643E4C4CECC; Fri, 4 Oct 2024 18:31:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1728066674; bh=kvOXRNJdLSkFt19dQGORrV4xUn+I7ThF4IlOi+Fs/2k=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=D76lt81ZCT3xCpVnKYdHduWXZaRX1J2ZDk4HZY9uH8H0RudBezA3eeqN+nt27crYl D7P1Vg80X6mUW9K0FQFdA3RlBtAPdU3KpCOumaLR2RRbNoqsMrMylEEta4uVEKVkGi 1x+oU11qvTSpNQL+jPGa9hEs6uIZ9H22IGf4W3UDhqjrBZhb8nffvXP7KP81+VlxjI TdgjjraBh4f+mDmr3pY1FBRDN818SBGPHRuFvtTY7tQcygWW8WDZ7HAkeBs+02DMDA dAd1yV+kFpMoK9BjIFZX26j93fp8w8HksGWWILT7MYOI9aNf2vq7VrQHh5M/ZvS530 mVRMa+9CqV45Q== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Gerald Schaefer , Heiko Carstens , Sasha Levin , agordeev@linux.ibm.com, gor@linux.ibm.com, linux-s390@vger.kernel.org Subject: [PATCH AUTOSEL 5.4 04/21] s390/mm: Add cond_resched() to cmm_alloc/free_pages() Date: Fri, 4 Oct 2024 14:30:39 -0400 Message-ID: <20241004183105.3675901-4-sashal@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20241004183105.3675901-1-sashal@kernel.org> References: <20241004183105.3675901-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 5.4.284 Content-Transfer-Encoding: 8bit From: Gerald Schaefer [ Upstream commit 131b8db78558120f58c5dc745ea9655f6b854162 ] Adding/removing large amount of pages at once to/from the CMM balloon can result in rcu_sched stalls or workqueue lockups, because of busy looping w/o cond_resched(). Prevent this by adding a cond_resched(). cmm_free_pages() holds a spin_lock while looping, so it cannot be added directly to the existing loop. Instead, introduce a wrapper function that operates on maximum 256 pages at once, and add it there. Signed-off-by: Gerald Schaefer Reviewed-by: Heiko Carstens Signed-off-by: Heiko Carstens Signed-off-by: Sasha Levin --- arch/s390/mm/cmm.c | 18 +++++++++++++++++- 1 file changed, 17 insertions(+), 1 deletion(-) diff --git a/arch/s390/mm/cmm.c b/arch/s390/mm/cmm.c index a51c892f14f3e..756aefbd05249 100644 --- a/arch/s390/mm/cmm.c +++ b/arch/s390/mm/cmm.c @@ -98,11 +98,12 @@ static long cmm_alloc_pages(long nr, long *counter, (*counter)++; spin_unlock(&cmm_lock); nr--; + cond_resched(); } return nr; } -static long cmm_free_pages(long nr, long *counter, struct cmm_page_array **list) +static long __cmm_free_pages(long nr, long *counter, struct cmm_page_array **list) { struct cmm_page_array *pa; unsigned long addr; @@ -126,6 +127,21 @@ static long cmm_free_pages(long nr, long *counter, struct cmm_page_array **list) return nr; } +static long cmm_free_pages(long nr, long *counter, struct cmm_page_array **list) +{ + long inc = 0; + + while (nr) { + inc = min(256L, nr); + nr -= inc; + inc = __cmm_free_pages(inc, counter, list); + if (inc) + break; + cond_resched(); + } + return nr + inc; +} + static int cmm_oom_notify(struct notifier_block *self, unsigned long dummy, void *parm) { -- 2.43.0