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_PASS,URIBL_BLOCKED autolearn=ham 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 2DFE2C04E53 for ; Wed, 15 May 2019 08:21:23 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id E314620862 for ; Wed, 15 May 2019 08:21:22 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=yandex-team.ru header.i=@yandex-team.ru header.b="fHGe8418" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E314620862 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=yandex-team.ru Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 7FB536B0005; Wed, 15 May 2019 04:21:22 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 7AC0F6B0006; Wed, 15 May 2019 04:21:22 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 6E9EC6B0007; Wed, 15 May 2019 04:21:22 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from mail-lj1-f198.google.com (mail-lj1-f198.google.com [209.85.208.198]) by kanga.kvack.org (Postfix) with ESMTP id 0BCA16B0005 for ; Wed, 15 May 2019 04:21:22 -0400 (EDT) Received: by mail-lj1-f198.google.com with SMTP id m2so282654ljj.13 for ; Wed, 15 May 2019 01:21:21 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:dkim-signature:subject:from:to:date:message-id :user-agent:mime-version:content-transfer-encoding; bh=rH/t30KXMBGr4dF0FJuUrEPHJpTL3NQhSuLj3xwva+0=; b=Oov+C4+0S2m8DXmq87u4K2Vy/vX8G/vSy7iiskiR1x0a3TZbrIidAiiVvGig1BCRMH HkY/xvNe2Ga7wH3Vk2EGqQGVDqWl7kYnziIAPBDrgjdSRrKJE4k4b3BTo5Sy/MEVwnLv 770rzO2aZq6o+ySFR7jtD2kBm7tzlEKSaDLFwKefr8G7Juq3hUs2PYuBGLtLylsJSF1N S8/ybA2Ld24C570zl+dV0+/h2DB+/6xw2RSFDmJPl2/7Y3FjrVqZKKlRG2rsFbR2Wdio GVrDPz3b0jyPlOmF03rAnywQwB8yvuUbKck8rx9yN8xN33H9ihZD/oenlxdcjZNoLeD0 KmzA== X-Gm-Message-State: APjAAAUJhxe8NeDbMr6ThO15LR24+2DdKoTAtn9ciFEYbHkNbeDgDlJ3 7ZDn5OC/tLFg6NJeO11I3jHRA+5MHVYDvcBd7TTdX/enZsOqOXEIdbXgjO+MsjV9TurzMYpsk3f Mgnj0dvYrVOoSBcXRRJJ5AS281okfVkDvJLjRUC7pGXOAUvFOTxlIXBl/uxhuAaQTeQ== X-Received: by 2002:a2e:568d:: with SMTP id k13mr19127016lje.194.1557908481148; Wed, 15 May 2019 01:21:21 -0700 (PDT) X-Google-Smtp-Source: APXvYqz14bp+ySn+TmfvPSF4v4EKF5bGKzF5O+uXT5uh/MuuxiWxR+WJQw9/0njCZEZluquDy6er X-Received: by 2002:a2e:568d:: with SMTP id k13mr19126972lje.194.1557908480306; Wed, 15 May 2019 01:21:20 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1557908480; cv=none; d=google.com; s=arc-20160816; b=nN+EQ1ja/Z0yPPDqjseezE6fHNAdQROe2KG74BKQgp+Mj0JklQYb9KOowDkz4Sgbgw KyoBVDsTy48H1FIKryegqHUik/HAIczxumDXOra7USzSFDxy8kj3YSdZvgi+jGAeDtdw xtGJhJBBpq4P5yutDR1qvZhtoDehSu6i5ldzfXOIBCBzx5ghtbDezQIWMyZ0kL7MLnmc T0GSh0mvW64EsoBdMIPZxIttyq63YFnEXtQRCKp7w/EwZTG6TZ5qQC16M/OREkCsEAyV uZsF6dnMg7Yh84if1TpMYmIxcbzJsC3BBROo97U4TSwSGzEdzzA6D+q5w3G9DQRw47NV VrXQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=content-transfer-encoding:mime-version:user-agent:message-id:date :to:from:subject:dkim-signature; bh=rH/t30KXMBGr4dF0FJuUrEPHJpTL3NQhSuLj3xwva+0=; b=aINiMQNhxa216eg+Aou4SO8TGHWVJs7rsYqwFVXzIPg/BVu1cAxELbUIahMx+9orxE EfuLm9zE54xag8TFqIarf6fLmtnnR/fkJaNjf7DMmpjAUntKYTSxOROjFazBlzp2SdJL AAXEO/08cooHoqb5gUVpCcYiCs0rI2p2PoQAStIofMMpcKJIDs2HtoVNQtPpxU5t5Frp 6svF/hRGLjQUIKVpR1pwAPAXfe7I8ERmR4llTko/byVppwSudnZSwhYMYbw11C2qV4aN oQW1Znn0wce8iW0FR7VNfhe1HgSLmDLC116FFvFqGyJBKTjnM3cLHHJeX9H2BgSHL0ek TDgg== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@yandex-team.ru header.s=default header.b=fHGe8418; spf=pass (google.com: domain of khlebnikov@yandex-team.ru designates 95.108.205.193 as permitted sender) smtp.mailfrom=khlebnikov@yandex-team.ru; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=yandex-team.ru Received: from forwardcorp1o.mail.yandex.net (forwardcorp1o.mail.yandex.net. [95.108.205.193]) by mx.google.com with ESMTP id p70si1033879ljp.7.2019.05.15.01.21.20 for ; Wed, 15 May 2019 01:21:20 -0700 (PDT) Received-SPF: pass (google.com: domain of khlebnikov@yandex-team.ru designates 95.108.205.193 as permitted sender) client-ip=95.108.205.193; Authentication-Results: mx.google.com; dkim=pass header.i=@yandex-team.ru header.s=default header.b=fHGe8418; spf=pass (google.com: domain of khlebnikov@yandex-team.ru designates 95.108.205.193 as permitted sender) smtp.mailfrom=khlebnikov@yandex-team.ru; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=yandex-team.ru Received: from mxbackcorp1o.mail.yandex.net (mxbackcorp1o.mail.yandex.net [IPv6:2a02:6b8:0:1a2d::301]) by forwardcorp1o.mail.yandex.net (Yandex) with ESMTP id A784B2E147B; Wed, 15 May 2019 11:21:19 +0300 (MSK) Received: from smtpcorp1p.mail.yandex.net (smtpcorp1p.mail.yandex.net [2a02:6b8:0:1472:2741:0:8b6:10]) by mxbackcorp1o.mail.yandex.net (nwsmtp/Yandex) with ESMTP id DwA5FsojOl-LJ0GRkIN; Wed, 15 May 2019 11:21:19 +0300 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yandex-team.ru; s=default; t=1557908479; bh=rH/t30KXMBGr4dF0FJuUrEPHJpTL3NQhSuLj3xwva+0=; h=Message-ID:Date:To:From:Subject; b=fHGe8418tN46yDfQFsQ6wSmHFaUCKDn9hk25OB75c5F8CZaDVuzJE3eqbZhBq6oTD KIU4i3rNGp8X6ahgcORt5JIudN3gzYuTn/Q8xJy2ex/jLMfmHd5kABXrLZg/WNLYXo n7e5PNwGicPSEkyRzqIMK5WMjAeFBYiNWrHhO/lE= Authentication-Results: mxbackcorp1o.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:ed19:3833:7ce1:2324]) by smtpcorp1p.mail.yandex.net (nwsmtp/Yandex) with ESMTPSA id fxC6AkQBIj-LJd0oVGu; Wed, 15 May 2019 11:21:19 +0300 (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client certificate not present) Subject: [PATCH] mm: use down_read_killable for locking mmap_sem in access_remote_vm From: Konstantin Khlebnikov To: linux-mm@kvack.org, Andrew Morton , linux-kernel@vger.kernel.org, Oleg Nesterov Date: Wed, 15 May 2019 11:21:18 +0300 Message-ID: <155790847881.2798.7160461383704600177.stgit@buzz> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: This function is used by ptrace and proc files like /proc/pid/cmdline and /proc/pid/environ. Return 0 (bytes read) if current task is killed. Mmap_sem could be locked for a long time or forever if something wrong. Signed-off-by: Konstantin Khlebnikov --- mm/memory.c | 4 +++- mm/nommu.c | 3 ++- 2 files changed, 5 insertions(+), 2 deletions(-) diff --git a/mm/memory.c b/mm/memory.c index 96f1d473c89a..2e6846d09023 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -4348,7 +4348,9 @@ int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm, void *old_buf = buf; int write = gup_flags & FOLL_WRITE; - down_read(&mm->mmap_sem); + if (down_read_killable(&mm->mmap_sem)) + return 0; + /* ignore errors, just check how much was successfully transferred */ while (len) { int bytes, ret, offset; diff --git a/mm/nommu.c b/mm/nommu.c index b492fd1fcf9f..cad8fb34088f 100644 --- a/mm/nommu.c +++ b/mm/nommu.c @@ -1791,7 +1791,8 @@ int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm, struct vm_area_struct *vma; int write = gup_flags & FOLL_WRITE; - down_read(&mm->mmap_sem); + if (down_read_killable(&mm->mmap_sem)) + return 0; /* the access must start within one of the target process's mappings */ vma = find_vma(mm, addr);