From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id DEA8BC433F5 for ; Wed, 27 Apr 2022 20:34:24 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 6BB696B0071; Wed, 27 Apr 2022 16:34:24 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 6460A6B0073; Wed, 27 Apr 2022 16:34:24 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 4BF656B0074; Wed, 27 Apr 2022 16:34:24 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (relay.a.hostedemail.com [64.99.140.24]) by kanga.kvack.org (Postfix) with ESMTP id 3B7AA6B0071 for ; Wed, 27 Apr 2022 16:34:24 -0400 (EDT) Received: from smtpin11.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 1CF8928F50 for ; Wed, 27 Apr 2022 20:34:24 +0000 (UTC) X-FDA: 79403811648.11.6B56692 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by imf05.hostedemail.com (Postfix) with ESMTP id 41F59100066 for ; Wed, 27 Apr 2022 20:34:16 +0000 (UTC) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 9FD7F61D70; Wed, 27 Apr 2022 20:34:22 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7B2B9C385A7; Wed, 27 Apr 2022 20:34:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1651091661; bh=QhjW6sqbQQAgxviJKBe4aWpl0/FEQUpaXuQ5s4h6qWg=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=q7Ns2THonpI64rhc55ciDClC+/tZwbo74ep5sf07OFCb26oZ1kUe9z79CZSpHNgzN VGMMisHTfPF3UFsfvxZ0AEUddllyF0mAQ72EsVMFRXrTjUdgq9z58WzHBUfQPEqp0O W6dNwKJCwvp4aKEyZx9Z3zIMHTeQ0j/etEQ7Dh8M= Date: Wed, 27 Apr 2022 13:34:20 -0700 From: Andrew Morton To: Vlastimil Babka Cc: Alexey Dobriyan , Matthew Wilcox , "Alex Xu (Hello71)" , Daniel Colascione , linux-api@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH] mm/smaps_rollup: return empty file for kthreads instead of ESRCH Message-Id: <20220427133420.2847e62203b9e10a106c86b2@linux-foundation.org> In-Reply-To: <83f49beb-52f7-15f6-3b53-97cac0030ca4@suse.cz> References: <20220413211357.26938-1-alex_y_xu.ref@yahoo.ca> <20220413211357.26938-1-alex_y_xu@yahoo.ca> <20220413142748.a5796e31e567a6205c850ae7@linux-foundation.org> <1649886492.rqei1nn3vm.none@localhost> <20220413160613.385269bf45a9ebb2f7223ca8@linux-foundation.org> <83f49beb-52f7-15f6-3b53-97cac0030ca4@suse.cz> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.33; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Stat-Signature: 77uistestg9inz7eswn643zs45aox5zc X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 41F59100066 X-Rspam-User: Authentication-Results: imf05.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=q7Ns2THo; dmarc=none; spf=pass (imf05.hostedemail.com: domain of akpm@linux-foundation.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org X-HE-Tag: 1651091656-833715 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, 14 Apr 2022 09:38:14 +0200 Vlastimil Babka wrote: > > Returning ESRCH is better so that programs don't waste time reading and > > closing empty files and instantiating useless inodes. > > Hm, unfortunately I don't remember why I put return -ESRCH for this case in > addition to get_proc_task() failing. I doubt it was a conscious decision to > treat kthreads differently - I think I would have preferred consistency with > maps/smaps. > > Can the awk use case be fixed with some flag to make it ignore the errors? This is all too hard. I think I'll drop the patch for now.