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=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 F1282C76186 for ; Mon, 29 Jul 2019 19:55:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C1B8821773 for ; Mon, 29 Jul 2019 19:55:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564430113; bh=vYx/zHP8wWU9g1UIxBmoe+KnVEnCZqWTIOJc41rRGsQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Ka7evbHyAEuFwU/oce7NrRqm7Z3YpLAY4yM3+pwqA/ysv1t1puk1On+DUhZr+2iOK pFMy9Hc++5YnSM5nVI5wYdSj1JsK78tYeKLb2I5RuH2fM6G09JqeiUYTf+eqRzKXZF +C+tu5ifTciC2tux2K8YvL/+uI6DQqNs+rcg/72M= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391039AbfG2TzM (ORCPT ); Mon, 29 Jul 2019 15:55:12 -0400 Received: from mail.kernel.org ([198.145.29.99]:47882 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2403890AbfG2TzI (ORCPT ); Mon, 29 Jul 2019 15:55:08 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 46E952054F; Mon, 29 Jul 2019 19:55:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564430107; bh=vYx/zHP8wWU9g1UIxBmoe+KnVEnCZqWTIOJc41rRGsQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=pnTPb4AjXNFB1atxPkhyren0de8uUY5M7C5OzZK6Eife3lxasvT3F4XHKO7wNmhTH kqXJSAHRJziPmm+FWxmDk8CvhQClgWxnEOvuiWlkZPgTqVubPevyza6k1YOnFBdz4K 57kJQp9pTU0n9JNu4lJo+t+xfCzJfR2G4MY3PTIE= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Konstantin Khlebnikov , Roman Gushchin , Cyrill Gorcunov , Kirill Tkhai , Michal Hocko , Alexey Dobriyan , Al Viro , Matthew Wilcox , =?UTF-8?q?Michal=20Koutn=C3=BD?= , Oleg Nesterov , Andrew Morton , Linus Torvalds , Sasha Levin Subject: [PATCH 5.2 159/215] proc: use down_read_killable mmap_sem for /proc/pid/clear_refs Date: Mon, 29 Jul 2019 21:22:35 +0200 Message-Id: <20190729190807.416089191@linuxfoundation.org> X-Mailer: git-send-email 2.22.0 In-Reply-To: <20190729190739.971253303@linuxfoundation.org> References: <20190729190739.971253303@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org [ Upstream commit c46038017fbdcac627b670c9d4176f1d0c2f5fa3 ] Do not remain stuck forever if something goes wrong. Using a killable lock permits cleanup of stuck tasks and simplifies investigation. Replace the only unkillable mmap_sem lock in clear_refs_write(). Link: http://lkml.kernel.org/r/156007493826.3335.5424884725467456239.stgit@buzz Signed-off-by: Konstantin Khlebnikov Reviewed-by: Roman Gushchin Reviewed-by: Cyrill Gorcunov Reviewed-by: Kirill Tkhai Acked-by: Michal Hocko Cc: Alexey Dobriyan Cc: Al Viro Cc: Matthew Wilcox Cc: Michal Koutný Cc: Oleg Nesterov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin --- fs/proc/task_mmu.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 1d9c63cd8a3c..abcd9513efff 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -1136,7 +1136,10 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf, goto out_mm; } - down_read(&mm->mmap_sem); + if (down_read_killable(&mm->mmap_sem)) { + count = -EINTR; + goto out_mm; + } tlb_gather_mmu(&tlb, mm, 0, -1); if (type == CLEAR_REFS_SOFT_DIRTY) { for (vma = mm->mmap; vma; vma = vma->vm_next) { -- 2.20.1