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[5.45.199.163]) by mx.google.com with ESMTPS id a6si5981008ljj.214.2019.06.09.03.08.53 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 09 Jun 2019 03:08:53 -0700 (PDT) Received-SPF: pass (google.com: domain of khlebnikov@yandex-team.ru designates 5.45.199.163 as permitted sender) client-ip=5.45.199.163; Authentication-Results: mx.google.com; dkim=pass header.i=@yandex-team.ru header.s=default header.b=JRKbcrjI; spf=pass (google.com: domain of khlebnikov@yandex-team.ru designates 5.45.199.163 as permitted sender) smtp.mailfrom=khlebnikov@yandex-team.ru; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=yandex-team.ru Received: from mxbackcorp1g.mail.yandex.net (mxbackcorp1g.mail.yandex.net [IPv6:2a02:6b8:0:1402::301]) by forwardcorp1j.mail.yandex.net (Yandex) with ESMTP id 1AFF12E087D; Sun, 9 Jun 2019 13:08:53 +0300 (MSK) Received: from smtpcorp1o.mail.yandex.net (smtpcorp1o.mail.yandex.net [2a02:6b8:0:1a2d::30]) by mxbackcorp1g.mail.yandex.net (nwsmtp/Yandex) with ESMTP id 13LYxQ2B9j-8pliI2hm; Sun, 09 Jun 2019 13:08:53 +0300 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yandex-team.ru; s=default; t=1560074933; bh=vE25/fE3GbSUmEmrdF2LzH942xvuS41f5y8rGOLXdnQ=; h=In-Reply-To:Message-ID:References:Date:To:From:Subject:Cc; b=JRKbcrjIO3Qau84WEWIcAh/pGsYAjU0pBAE0iOqS7wdR0k5OSt+AWz7uKQJI4mJg6 8827ndi69XToznkB0q2AePqeqDvA/uq02G6iPx4++PVKEp0BXjJpvgdvNRgAY29Sw6 RRh4rf2ePf7A9V7TIg/fu2WM1HrJJvQgXF2H2b2Q= Authentication-Results: mxbackcorp1g.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 2fhLdaNKBQ-8pYaK4tB; Sun, 09 Jun 2019 13:08:51 +0300 (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client certificate not present) Subject: [PATCH v2 1/6] proc: use down_read_killable mmap_sem for /proc/pid/maps 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 13:08:51 +0300 Message-ID: <156007493160.3335.14447544314127417266.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 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: Do not stuck forever if something wrong. Killable lock allows to cleanup stuck tasks and simplifies investigation. This function also used for /proc/pid/smaps. 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 | 6 +++++- fs/proc/task_nommu.c | 6 +++++- 2 files changed, 10 insertions(+), 2 deletions(-) diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 01d4eb0e6bd1..2bf210229daf 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -166,7 +166,11 @@ static void *m_start(struct seq_file *m, loff_t *ppos) if (!mm || !mmget_not_zero(mm)) return NULL; - down_read(&mm->mmap_sem); + if (down_read_killable(&mm->mmap_sem)) { + mmput(mm); + return ERR_PTR(-EINTR); + } + hold_task_mempolicy(priv); priv->tail_vma = get_gate_vma(mm); diff --git a/fs/proc/task_nommu.c b/fs/proc/task_nommu.c index 36bf0f2e102e..7907e6419e57 100644 --- a/fs/proc/task_nommu.c +++ b/fs/proc/task_nommu.c @@ -211,7 +211,11 @@ static void *m_start(struct seq_file *m, loff_t *pos) if (!mm || !mmget_not_zero(mm)) return NULL; - down_read(&mm->mmap_sem); + if (down_read_killable(&mm->mmap_sem)) { + mmput(mm); + return ERR_PTR(-EINTR); + } + /* start from the Nth VMA */ for (p = rb_first(&mm->mm_rb); p; p = rb_next(p)) if (n-- == 0)