From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f198.google.com (mail-pf0-f198.google.com [209.85.192.198]) by kanga.kvack.org (Postfix) with ESMTP id 0ED596B0069 for ; Mon, 7 Nov 2016 10:31:50 -0500 (EST) Received: by mail-pf0-f198.google.com with SMTP id n85so51724188pfi.4 for ; Mon, 07 Nov 2016 07:31:50 -0800 (PST) Received: from EUR02-AM5-obe.outbound.protection.outlook.com (mail-eopbgr00104.outbound.protection.outlook.com. [40.107.0.104]) by mx.google.com with ESMTPS id o69si31714306pfi.265.2016.11.07.07.01.32 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Mon, 07 Nov 2016 07:01:32 -0800 (PST) Subject: Re: [PATCH 4/7] mm: defer vmalloc from atomic context References: <1477149440-12478-1-git-send-email-hch@lst.de> <1477149440-12478-5-git-send-email-hch@lst.de> <25c117ae-6d06-9846-6a88-ae6221ad6bfe@virtuozzo.com> From: Andrey Ryabinin Message-ID: Date: Mon, 7 Nov 2016 18:01:45 +0300 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Joel Fernandes Cc: Christoph Hellwig , Andrew Morton , Jisheng Zhang , Chris Wilson , John Dias , "open list:MEMORY MANAGEMENT" , linux-rt-users@vger.kernel.org, LKML , Andy Lutomirski On 11/05/2016 06:43 AM, Joel Fernandes wrote: > On Mon, Oct 24, 2016 at 8:44 AM, Andrey Ryabinin > wrote: >> >> >> On 10/22/2016 06:17 PM, Christoph Hellwig wrote: >>> We want to be able to use a sleeping lock for freeing vmap to keep >>> latency down. For this we need to use the deferred vfree mechanisms >>> no only from interrupt, but from any atomic context. >>> >>> Signed-off-by: Christoph Hellwig >>> --- >>> mm/vmalloc.c | 2 +- >>> 1 file changed, 1 insertion(+), 1 deletion(-) >>> >>> diff --git a/mm/vmalloc.c b/mm/vmalloc.c >>> index a4e2cec..bcc1a64 100644 >>> --- a/mm/vmalloc.c >>> +++ b/mm/vmalloc.c >>> @@ -1509,7 +1509,7 @@ void vfree(const void *addr) >>> >>> if (!addr) >>> return; >>> - if (unlikely(in_interrupt())) { >>> + if (unlikely(in_atomic())) { >> >> in_atomic() cannot always detect atomic context, thus it shouldn't be used here. >> You can add something like vfree_in_atomic() and use it in atomic call sites. >> > > So because in_atomic doesn't work for !CONFIG_PREEMPT kernels, can we > always defer the work in these cases? > > So for non-preemptible kernels, we always defer: > > if (!IS_ENABLED(CONFIG_PREEMPT) || in_atomic()) { > // defer > } > > Is this fine? Or any other ideas? > What's wrong with my idea? We can add vfree_in_atomic() and use it to free vmapped stacks and for any other places where vfree() used 'in_atomict() && !in_interrupt()' context. -- 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