From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lf0-f69.google.com (mail-lf0-f69.google.com [209.85.215.69]) by kanga.kvack.org (Postfix) with ESMTP id 258DE6B0069 for ; Wed, 19 Oct 2016 09:05:55 -0400 (EDT) Received: by mail-lf0-f69.google.com with SMTP id x79so8290492lff.2 for ; Wed, 19 Oct 2016 06:05:55 -0700 (PDT) Received: from newverein.lst.de (verein.lst.de. [213.95.11.211]) by mx.google.com with ESMTPS id a10si54242155wjd.63.2016.10.19.06.05.53 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 19 Oct 2016 06:05:53 -0700 (PDT) Date: Wed, 19 Oct 2016 15:05:52 +0200 From: Christoph Hellwig Subject: Re: [PATCH 2/6] mm: mark all calls into the vmalloc subsystem as potentially sleeping Message-ID: <20161019130552.GB5876@lst.de> References: <1476773771-11470-1-git-send-email-hch@lst.de> <1476773771-11470-3-git-send-email-hch@lst.de> <20161019111541.GQ29358@nuc-i3427.alporthouse.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20161019111541.GQ29358@nuc-i3427.alporthouse.com> Sender: owner-linux-mm@kvack.org List-ID: To: Chris Wilson Cc: Christoph Hellwig , akpm@linux-foundation.org, joelaf@google.com, jszhang@marvell.com, joaodias@google.com, linux-mm@kvack.org, linux-rt-users@vger.kernel.org, linux-kernel@vger.kernel.org, Andy Lutomirski On Wed, Oct 19, 2016 at 12:15:41PM +0100, Chris Wilson wrote: > On Tue, Oct 18, 2016 at 08:56:07AM +0200, Christoph Hellwig wrote: > > This is how everyone seems to already use them, but let's make that > > explicit. > > Ah, found an exception, vmapped stacks: Oh, fun. So if we can't require vfree to be called from process context we also can't use a mutex to wait for the vmap flushing. Given that we free stacks from the scheduler context switch I also fear there is no good way to get a sleepable context there. The only other idea I had was to use vmap_area_lock for the protection that purge_lock currently provides, but that would require some serious refactoring to avoid recursive locking first. -- 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