From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lb0-f180.google.com (mail-lb0-f180.google.com [209.85.217.180]) by kanga.kvack.org (Postfix) with ESMTP id B87116B0032 for ; Wed, 11 Feb 2015 00:34:47 -0500 (EST) Received: by mail-lb0-f180.google.com with SMTP id z12so1162653lbi.11 for ; Tue, 10 Feb 2015 21:34:46 -0800 (PST) Received: from mail-la0-f41.google.com (mail-la0-f41.google.com. [209.85.215.41]) by mx.google.com with ESMTPS id y9si13636515lbr.7.2015.02.10.21.34.45 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 10 Feb 2015 21:34:45 -0800 (PST) Received: by labpn19 with SMTP id pn19so1249076lab.4 for ; Tue, 10 Feb 2015 21:34:45 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <20150211034307.GA2932@kroah.com> References: <20150203231211.486950145@linuxfoundation.org> <20150203231212.223123220@linuxfoundation.org> <20150211034307.GA2932@kroah.com> Date: Wed, 11 Feb 2015 09:34:44 +0400 Message-ID: Subject: Re: [PATCH 3.18 04/57] vm: add VM_FAULT_SIGSEGV handling support From: Konstantin Khlebnikov Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org List-ID: To: Greg Kroah-Hartman Cc: Linux Kernel Mailing List , Stable , Jan Engelhardt , linux-arch@vger.kernel.org, Linus Torvalds , "linux-mm@kvack.org" On Wed, Feb 11, 2015 at 6:43 AM, Greg Kroah-Hartman wrote: > On Tue, Feb 10, 2015 at 12:22:41PM +0400, Konstantin Khlebnikov wrote: >> I've found regression: >> >> [ 257.139907] ================================================ >> [ 257.139909] [ BUG: lock held when returning to user space! ] >> [ 257.139912] 3.18.6-debug+ #161 Tainted: G U >> [ 257.139914] ------------------------------------------------ >> [ 257.139916] python/22843 is leaving the kernel with locks still held! >> [ 257.139918] 1 lock held by python/22843: >> [ 257.139920] #0: (&mm->mmap_sem){++++++}, at: [] >> __do_page_fault+0x162/0x570 >> >> upstream commit 7fb08eca45270d0ae86e1ad9d39c40b7a55d0190 must be backported too. > > Ah, nice, I missed that one. How did you test this? I've catched hang on mmap_sem in some python self-test inside exherbo chroot. With that patch test has finished successfully. It seems the only way to tigger this is stack-overflow: for now VM_FAULT_SIGSEGV is returned only if kernel cannot add guard page when stack expands. > > thanks, > > greg k-h -- 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