Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S938961AbcJSQbS (ORCPT ); Wed, 19 Oct 2016 12:31:18 -0400 Received: from verein.lst.de ([213.95.11.211]:42900 "EHLO newverein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932857AbcJSQbO (ORCPT ); Wed, 19 Oct 2016 12:31:14 -0400 Date: Wed, 19 Oct 2016 18:31:12 +0200 From: Christoph Hellwig To: Andy Lutomirski Cc: Christoph Hellwig , Chris Wilson , Andrew Morton , joelaf@google.com, jszhang@marvell.com, joaodias@google.com, "linux-mm@kvack.org" , linux-rt-users@vger.kernel.org, "linux-kernel@vger.kernel.org" Subject: Re: [PATCH 2/6] mm: mark all calls into the vmalloc subsystem as potentially sleeping Message-ID: <20161019163112.GA31091@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> <20161019130552.GB5876@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 966 Lines: 27 On Wed, Oct 19, 2016 at 08:34:40AM -0700, Andy Lutomirski wrote: > > It would be quite awkward for a task stack to get freed from a > sleepable context, because the obvious sleepable context is the task > itself, and it still needs its stack. This was true even in the old > regime when task stacks were freed from RCU context. > > But vfree has a magic automatic deferral mechanism. Couldn't you make > the non-deferred case might_sleep()? But it's only magic from interrupt context.. Chris, does this patch make virtually mapped stack work for you again? diff --git a/mm/vmalloc.c b/mm/vmalloc.c index f2481cb..942e02d 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -1533,7 +1533,7 @@ void vfree(const void *addr) if (!addr) return; - if (unlikely(in_interrupt())) { + if (in_interrupt() || in_atomic()) { struct vfree_deferred *p = this_cpu_ptr(&vfree_deferred); if (llist_add((struct llist_node *)addr, &p->list)) schedule_work(&p->wq);