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 8B3BF1DED49; Wed, 6 Nov 2024 12:18:13 +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=1730895493; cv=none; b=O//+Iyz5CURx/q1aDz80Z38GKB9rvIbPq7RaT2suQYE8LAGk67lKp91NJEBnS6/8aApEPEq4Aqb+6mNqOtfrt1U8y41Oru4DJPopoM2J6DtnjsYf0avCsPYjAbkY7MIrNKx4hNhJmmrRK1kNNoHvjXKHUceIHlEN5EhUscyqh30= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730895493; c=relaxed/simple; bh=KpWuidg9YQ4lEoTd06nGD60v5elxH1H9X/Wyyd/UDUg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=h2xupT2DWsKCTC9XgM+VKQN2zN8WC6pjUYdelAJkYYLQpKamHydfUMif1Bxp8rwgxSeARY60YOb338vFa1Mj0gXlRkUqnZiYm9Ox+OMLsmanHa8N6O9Uu5pPKa/OqkrGmjayJCCacGl0L2Qng7vb06h5vfmqD9lhEP/fbhNCF4c= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=FmCtYluK; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="FmCtYluK" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 06436C4CED3; Wed, 6 Nov 2024 12:18:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1730895493; bh=KpWuidg9YQ4lEoTd06nGD60v5elxH1H9X/Wyyd/UDUg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=FmCtYluK2UqbARjoM5dZ5jtqHH3sFB8sQYQRb6otTPHc+s21rHKVomxr9T3SJFYsb NA//cnYOgf/inwNRyxazX8dZYUIkB9QLOh8Ln3KyqVTtcoQDyW+41U+/0pR2XOlZ46 HYKr7gMlHIn3n9xUYckeJ3S7FGIj2jWnfwVqsSPU= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Gerald Schaefer , Heiko Carstens , Sasha Levin Subject: [PATCH 4.19 236/350] s390/mm: Add cond_resched() to cmm_alloc/free_pages() Date: Wed, 6 Nov 2024 13:02:44 +0100 Message-ID: <20241106120326.787535901@linuxfoundation.org> X-Mailer: git-send-email 2.47.0 In-Reply-To: <20241106120320.865793091@linuxfoundation.org> References: <20241106120320.865793091@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 4.19-stable review patch. If anyone has any objections, please let me know. ------------------ 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