From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f198.google.com (mail-wr0-f198.google.com [209.85.128.198]) by kanga.kvack.org (Postfix) with ESMTP id A2B346B0292 for ; Mon, 5 Jun 2017 17:44:04 -0400 (EDT) Received: by mail-wr0-f198.google.com with SMTP id z70so11378830wrc.1 for ; Mon, 05 Jun 2017 14:44:04 -0700 (PDT) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org. [140.211.169.12]) by mx.google.com with ESMTPS id v70si9527975wmd.29.2017.06.05.14.44.03 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 05 Jun 2017 14:44:03 -0700 (PDT) Date: Mon, 5 Jun 2017 14:44:01 -0700 From: Andrew Morton Subject: Re: Sleeping BUG in khugepaged for i586 Message-Id: <20170605144401.5a7e62887b476f0732560fa0@linux-foundation.org> In-Reply-To: <968ae9a9-5345-18ca-c7ce-d9beaf9f43b6@lwfinger.net> References: <968ae9a9-5345-18ca-c7ce-d9beaf9f43b6@lwfinger.net> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Larry Finger Cc: LKML , linux-mm@kvack.org On Sat, 3 Jun 2017 14:24:26 -0500 Larry Finger wrote: > I recently turned on locking diagnostics for a Dell Latitude D600 laptop, which > requires a 32-bit kernel. In the log I found the following: > > BUG: sleeping function called from invalid context at mm/khugepaged.c:655 > in_atomic(): 1, irqs_disabled(): 0, pid: 20, name: khugepaged > 1 lock held by khugepaged/20: > #0: (&mm->mmap_sem){++++++}, at: [] > collapse_huge_page.isra.47+0x439/0x1240 > CPU: 0 PID: 20 Comm: khugepaged Tainted: G W > 4.12.0-rc1-wl-12125-g952a068 #80 > Hardware name: Dell Computer Corporation Latitude D600 > /03U652, BIOS A05 05/29/2003 > Call Trace: > dump_stack+0x76/0xb2 > ___might_sleep+0x174/0x230 > collapse_huge_page.isra.47+0xacf/0x1240 > khugepaged_scan_mm_slot+0x41e/0xc00 > ? _raw_spin_lock+0x46/0x50 > khugepaged+0x277/0x4f0 > ? prepare_to_wait_event+0xe0/0xe0 > kthread+0xeb/0x120 > ? khugepaged_scan_mm_slot+0xc00/0xc00 > ? kthread_create_on_node+0x30/0x30 > ret_from_fork+0x21/0x30 > > I have no idea when this problem was introduced. Of course, I will test any > proposed fixes. > Odd. There's nothing wrong with cond_resched() while holding mmap_sem. It looks like khugepaged forgot to do a spin_unlock somewhere and we leaked a preempt_count. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org