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 X-Spam-Level: X-Spam-Status: No, score=-7.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 20F1CC468BD for ; Sun, 9 Jun 2019 10:09:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EDD0620693 for ; Sun, 9 Jun 2019 10:09:04 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=yandex-team.ru header.i=@yandex-team.ru header.b="HEBN1BfE" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728235AbfFIKJD (ORCPT ); Sun, 9 Jun 2019 06:09:03 -0400 Received: from forwardcorp1j.mail.yandex.net ([5.45.199.163]:46698 "EHLO forwardcorp1j.mail.yandex.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728149AbfFIKJA (ORCPT ); Sun, 9 Jun 2019 06:09:00 -0400 Received: from mxbackcorp2j.mail.yandex.net (mxbackcorp2j.mail.yandex.net [IPv6:2a02:6b8:0:1619::119]) by forwardcorp1j.mail.yandex.net (Yandex) with ESMTP id 265F52E097B; Sun, 9 Jun 2019 13:08:57 +0300 (MSK) Received: from smtpcorp1o.mail.yandex.net (smtpcorp1o.mail.yandex.net [2a02:6b8:0:1a2d::30]) by mxbackcorp2j.mail.yandex.net (nwsmtp/Yandex) with ESMTP id pNBtwZTYyg-8udqp0pt; Sun, 09 Jun 2019 13:08:57 +0300 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yandex-team.ru; s=default; t=1560074937; bh=3rk+4uRwl46CAyP7ka3QhboNqPwEZHBXTQqkcXWKDZU=; h=In-Reply-To:Message-ID:References:Date:To:From:Subject:Cc; b=HEBN1BfECtA+NWOl1NyhYjybz8lV9L5DriON81fOTee7qLzo9B1x324RjmVk79R1d EPwmvCOgjHYCRKWT83RsO0l/Q9io6+Tangbs3bDwNXlFGnRXGUalmBWJ7ENrOSa5Rs E5y5f08BToJC0UDl/kAKm5SjyMhHRX/j+Ms+1QrE= Authentication-Results: mxbackcorp2j.mail.yandex.net; dkim=pass header.i=@yandex-team.ru Received: from dynamic-red.dhcp.yndx.net (dynamic-red.dhcp.yndx.net [2a02:6b8:0:40c:3d25:9e27:4f75:a150]) by smtpcorp1o.mail.yandex.net (nwsmtp/Yandex) with ESMTPSA id Qx30l6oFjQ-8uYGIqxH; Sun, 09 Jun 2019 13:08:56 +0300 (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client certificate not present) Subject: [PATCH v2 3/6] proc: use down_read_killable mmap_sem for /proc/pid/pagemap From: Konstantin Khlebnikov To: linux-mm@kvack.org, Andrew Morton , linux-kernel@vger.kernel.org Cc: Oleg Nesterov , Matthew Wilcox , Michal Hocko , Cyrill Gorcunov , Kirill Tkhai , Michal =?utf-8?q?Koutn=C3=BD?= , Al Viro , Roman Gushchin Date: Sun, 09 Jun 2019 13:08:56 +0300 Message-ID: <156007493638.3335.4872164955523928492.stgit@buzz> In-Reply-To: <156007465229.3335.10259979070641486905.stgit@buzz> References: <156007465229.3335.10259979070641486905.stgit@buzz> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Do not stuck forever if something wrong. Killable lock allows to cleanup stuck tasks and simplifies investigation. Signed-off-by: Konstantin Khlebnikov Reviewed-by: Roman Gushchin Reviewed-by: Cyrill Gorcunov Reviewed-by: Kirill Tkhai Acked-by: Michal Hocko --- fs/proc/task_mmu.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 781879a91e3b..78bed6adc62d 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -1547,7 +1547,9 @@ static ssize_t pagemap_read(struct file *file, char __user *buf, /* overflow ? */ if (end < start_vaddr || end > end_vaddr) end = end_vaddr; - down_read(&mm->mmap_sem); + ret = down_read_killable(&mm->mmap_sem); + if (ret) + goto out_free; ret = walk_page_range(start_vaddr, end, &pagemap_walk); up_read(&mm->mmap_sem); start_vaddr = end;