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 9C8581CACE3; Mon, 14 Oct 2024 15:28:43 +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=1728919723; cv=none; b=sCaygJNP/FcIntXtcvC6M+AXi36ajSyo48THCkkU0pIGqlgYtM1udhBtBZsrrrlsNnry3RJh2wmSC64HC3gdfG1EvoyQaKNFsHloGK0Igxi9hSWJ9pw1ZCWkqfaD/tEamlbb9VLJCd1ex4lq+2+N4GiK17f0l4xkkjAkfn2XqKw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728919723; c=relaxed/simple; bh=C/kJkLs6lvNjcUsQIJoGzImYSry0Mj9QOSnRFRmTkSw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=NjmeePXMoqBChY9y9WLSngc+tjKE6LTxEurN/Wk/MdmShPWwVqW/uIX9XUj7x1tv/tiV8XBY9Q6FzMB/PKbIn6BqucDe0c9u3Pi0dXAZxyMeAay2JKig2ClIz+XxJHvEKSjWvXMf11HYPpuSc+Kps0vcNmlIru53ASiS4fj/rqw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=p/adQCqP; 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="p/adQCqP" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B3274C4CEC3; Mon, 14 Oct 2024 15:28:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1728919723; bh=C/kJkLs6lvNjcUsQIJoGzImYSry0Mj9QOSnRFRmTkSw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=p/adQCqPlwwILoRMcca2Zl+Qv46QVVnv8qV6QRxCh46i55q/t8ePKr3t1SbhUSzDQ avf5jOdDIYCEMcXv+IvV7Kro9/KYj4Jt9pjUT4JBtWb6YwvHKE3xvVMdYLGVNH2aJI CPbeKf4ZUXNlxrUCgEl7IcGaTkMUnATUE913fnBw= 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 6.1 689/798] s390/mm: Add cond_resched() to cmm_alloc/free_pages() Date: Mon, 14 Oct 2024 16:20:43 +0200 Message-ID: <20241014141245.140440318@linuxfoundation.org> X-Mailer: git-send-email 2.47.0 In-Reply-To: <20241014141217.941104064@linuxfoundation.org> References: <20241014141217.941104064@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 6.1-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 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