Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752012AbdHHFeK (ORCPT ); Tue, 8 Aug 2017 01:34:10 -0400 Received: from ozlabs.org ([103.22.144.67]:38963 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751974AbdHHFeF (ORCPT ); Tue, 8 Aug 2017 01:34:05 -0400 From: Michael Ellerman To: Andrew Morton , Jonathan Toppins Cc: linux-mm@kvack.org, linux-rdma@vger.kernel.org, dledford@redhat.com, Michal Hocko , Vlastimil Babka , Mel Gorman , Hillf Danton , open list Subject: Re: [PATCH] mm: ratelimit PFNs busy info message In-Reply-To: <20170802141720.228502368b534f517e3107ff@linux-foundation.org> References: <499c0f6cc10d6eb829a67f2a4d75b4228a9b356e.1501695897.git.jtoppins@redhat.com> <20170802141720.228502368b534f517e3107ff@linux-foundation.org> User-Agent: Notmuch/0.21 (https://notmuchmail.org) Date: Tue, 08 Aug 2017 15:34:02 +1000 Message-ID: <87k22eoc6t.fsf@concordia.ellerman.id.au> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 871 Lines: 23 Andrew Morton writes: > On Wed, 2 Aug 2017 13:44:57 -0400 Jonathan Toppins wrote: > >> The RDMA subsystem can generate several thousand of these messages per >> second eventually leading to a kernel crash. Ratelimit these messages >> to prevent this crash. > > Well... why are all these EBUSY's occurring? It sounds inefficient (at > least) but if it is expected, normal and unavoidable then perhaps we > should just remove that message altogether? We see them on powerpc sometimes when CMA is unable to make large allocations for the hash table of a KVM guest. At least in that context they're not useful, CMA will try the allocation again, and if it really can't allocate then CMA will print more useful information itself. So I'd vote for dropping the message and letting the callers decide what to do. cheers