Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753451Ab3HBBkL (ORCPT ); Thu, 1 Aug 2013 21:40:11 -0400 Received: from mail-oa0-f43.google.com ([209.85.219.43]:48180 "EHLO mail-oa0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751448Ab3HBBkJ (ORCPT ); Thu, 1 Aug 2013 21:40:09 -0400 MIME-Version: 1.0 In-Reply-To: <20130731201708.efa5ae87.akpm@linux-foundation.org> References: <1374842669-22844-1-git-send-email-mhocko@suse.cz> <20130729135743.c04224fb5d8e64b2730d8263@linux-foundation.org> <51F9D1F6.4080001@jp.fujitsu.com> <20130731201708.efa5ae87.akpm@linux-foundation.org> From: KOSAKI Motohiro Date: Thu, 1 Aug 2013 21:39:48 -0400 X-Google-Sender-Auth: pwSdKodC2whHbpRlq7G9sgIa054 Message-ID: Subject: Re: [PATCH resend] drop_caches: add some documentation and info message To: Andrew Morton Cc: Michal Hocko , "linux-mm@kvack.org" , LKML , dave.hansen@intel.com, KAMEZAWA Hiroyuki , bp@suse.de, Dave Hansen Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1568 Lines: 36 On Wed, Jul 31, 2013 at 11:17 PM, Andrew Morton wrote: > On Wed, 31 Jul 2013 23:11:50 -0400 KOSAKI Motohiro wrote: > >> >> --- a/fs/drop_caches.c >> >> +++ b/fs/drop_caches.c >> >> @@ -59,6 +59,8 @@ int drop_caches_sysctl_handler(ctl_table *table, int write, >> >> if (ret) >> >> return ret; >> >> if (write) { >> >> + printk(KERN_INFO "%s (%d): dropped kernel caches: %d\n", >> >> + current->comm, task_pid_nr(current), sysctl_drop_caches); >> >> if (sysctl_drop_caches & 1) >> >> iterate_supers(drop_pagecache_sb, NULL); >> >> if (sysctl_drop_caches & 2) >> > >> > How about we do >> > >> > if (!(sysctl_drop_caches & 4)) >> > printk(....) >> > >> > so people can turn it off if it's causing problems? >> >> The best interface depends on the purpose. If you want to detect crazy application, >> we can't assume an application co-operate us. So, I doubt this works. > > You missed the "!". I'm proposing that setting the new bit 2 will > permit people to prevent the new printk if it is causing them problems. No I don't. I'm sure almost all abuse users think our usage is correct. Then, I can imagine all crazy applications start to use this flag eventually. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/