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=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 DC309C433FF for ; Mon, 29 Jul 2019 19:43:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A862621773 for ; Mon, 29 Jul 2019 19:43:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564429423; bh=7IlkZw/2t+39Kdv3zI+iZeNRgsWP2mSgdijooRbHjyc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=QH8Ybx3a8Ld+owlSn4/1ZQxuLhHasXcI9ItV3OZ0iGHH8L59l3bxu1RT8rns/Ijog 0gjS9BZQY6Snh9bCI+2yOu8neKEVy0kunnHh4JwwWYcDr+5rYPiA3GKShE8za0oUND bt1MB8bDstB/cXft2waA3rVfk0FQNZ6Qz8Lc/OL0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389686AbfG2Tnl (ORCPT ); Mon, 29 Jul 2019 15:43:41 -0400 Received: from mail.kernel.org ([198.145.29.99]:60008 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389146AbfG2Tng (ORCPT ); Mon, 29 Jul 2019 15:43:36 -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 3E3CC20C01; Mon, 29 Jul 2019 19:43:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564429415; bh=7IlkZw/2t+39Kdv3zI+iZeNRgsWP2mSgdijooRbHjyc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=D7sarOmRUsCiMgfOgY6szA/aRvokh5q4x/mOZMI4j8bBHYu1RJNa/A1+oJD9y4l5q r4hVASvijt3JoXLDXUZTUkAvT4BVHa52fYI/kJ9VcDhL6LOLo2MaquPOIJSoiPT0SO C0eWNnbs6OV8zDf+OrS16SRGwSn0qLr493e6BSJI= 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 4.19 091/113] proc: use down_read_killable mmap_sem for /proc/pid/clear_refs Date: Mon, 29 Jul 2019 21:22:58 +0200 Message-Id: <20190729190717.223896566@linuxfoundation.org> X-Mailer: git-send-email 2.22.0 In-Reply-To: <20190729190655.455345569@linuxfoundation.org> References: <20190729190655.455345569@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 74965e17ffd5..195fbbaf77d4 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -1131,7 +1131,10 @@ 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