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 084FE20D9CF; Fri, 4 Oct 2024 18:27:27 +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=1728066447; cv=none; b=bv0H/nJqFqC6vMHZXWUDA1y/K/v0XaG8FAWAPZP5PnWCXbeeXL93iayrmIuOoAdOTwsGFfwlm0vg2kILa61bTVzMxj80szQynF1M3V1FITIDPkQL6xKw0SJtUe21ry9XjYNfVGfpXLYRBHfJeIwy8MlGED3pWCGCdB1RiO85X4Q= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728066447; c=relaxed/simple; bh=q4yL+SJ+F1XeQsOq8Y8jFlNT8NBvrQhYPz7C9FZjtCc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=QiXWle3oD9ob6BbTKOY7hWZK4GsxlAVSvWJI+Q55ABMhh+mPedyvzxMGB0KXSktDy6CRsdKWT042Gcnx+u80Hb04WU0wh6GT4tQ7QAvSlHXlsyjMVjR4JTh7919/bBKI3WIezftzUD7tVH+WUGNUEAwm45ch3zvDMgbouFWQE90= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Ctm9mBdh; 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="Ctm9mBdh" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EDF9AC4CECE; Fri, 4 Oct 2024 18:27:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1728066446; bh=q4yL+SJ+F1XeQsOq8Y8jFlNT8NBvrQhYPz7C9FZjtCc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Ctm9mBdhwjAEExdUocOKjU2vo/yDrVZFS2ClscbWTUfrCPR3LRaLehwJfckitqL7Y 8dg4/IhGk4mYsOn0UImull4AF0ogsSPl/oLQOdzZ4jwCPu/WVskB5nSbjLU1MZvJ4E VXwy/8r0a/ctce5aBDadtLpGtOQdnJKfQ74bgzXVF0fkU1J8uC+LGZ1RrXepQZutkh o0IAppL+yRBsfTCw1B3b3cqQJLLA9QckKwlPDCCZQJcIDU47dpk6/gpcO21lZsvPaM 9Hyq2aUX/bGQPqpe0sfyvHwdP03J8GOGcaQd4LGo8PjDl1ItplFZtOGTEBMjlp49MY 0cSgF+D/OpoBQ== 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 6.1 04/42] s390/mm: Add cond_resched() to cmm_alloc/free_pages() Date: Fri, 4 Oct 2024 14:26:15 -0400 Message-ID: <20241004182718.3673735-4-sashal@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20241004182718.3673735-1-sashal@kernel.org> References: <20241004182718.3673735-1-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 6.1.112 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 9141ed4c52e90..02e030ad38c5f 100644 --- a/arch/s390/mm/cmm.c +++ b/arch/s390/mm/cmm.c @@ -95,11 +95,12 @@ 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; @@ -123,6 +124,21 @@ 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