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 B7D49CA101A for ; Sat, 31 Aug 2024 00:59:07 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 2850C6B0288; Fri, 30 Aug 2024 20:59:07 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 233696B0289; Fri, 30 Aug 2024 20:59:07 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0FB956B028A; Fri, 30 Aug 2024 20:59:07 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id DD3B36B0288 for ; Fri, 30 Aug 2024 20:59:06 -0400 (EDT) Received: from smtpin18.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id 5EB91807C2 for ; Sat, 31 Aug 2024 00:59:06 +0000 (UTC) X-FDA: 82510731492.18.8227580 Received: from nyc.source.kernel.org (nyc.source.kernel.org [147.75.193.91]) by imf20.hostedemail.com (Postfix) with ESMTP id B91061C0009 for ; Sat, 31 Aug 2024 00:59:04 +0000 (UTC) Authentication-Results: imf20.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=AunijzZH; spf=pass (imf20.hostedemail.com: domain of akpm@linux-foundation.org designates 147.75.193.91 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org; dmarc=none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1725065899; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=5SdA1UQ9Vp8O3Zeldymwpe7f/+rqVfzT8tyS/TMHyFM=; b=fCmVIcR9XKcYqmfI3H5SIZ3WlBs8mhOogtt5U5hZtMYV4Gt82WkvkOXXaHtHBR6S+nTMpU 5U/5aJdUdR48Ts4UGPctzTqSkX8RqY5BFgtagxaTld/2sLWPCCNyvC3YXugavp69iviMm/ +D26/0VHEFpwuJ744FTqVIL2B7lb5tE= ARC-Authentication-Results: i=1; imf20.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=AunijzZH; spf=pass (imf20.hostedemail.com: domain of akpm@linux-foundation.org designates 147.75.193.91 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org; dmarc=none ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1725065899; a=rsa-sha256; cv=none; b=OquaXDfHxyupyj+IQlt8PHlaCNOiS6lRM9NCz7MX0/Ih9veVaqdTuYVLdzyx8f1D7uggY0 z76tVH1wMkAcFiQ4DL41GzGO1bLH7LwNIWsEDuhBL7rz5qsE97zwXq4VSGR9auQuOYUBaN L99F5ZdQWLlsgjagqfxq4gAAgpGJA0g= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by nyc.source.kernel.org (Postfix) with ESMTP id E09DAA44601; Sat, 31 Aug 2024 00:58:56 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 65657C4CEC2; Sat, 31 Aug 2024 00:59:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1725065943; bh=HjXW+A1M0PT2CqqxncN2ISGNKCnPAFywGMSvYvNaWt4=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=AunijzZHoDfDlJwGqw2S9WHH1G6SZly0dIowtzTlTpRMwL3yNfAexaEDeoV2GHXSZ gnrIErqerX3udeXvhFVY9yNHAa9wxzsFObqRIMtHb4UtjVvHsIbwGJFdzu1BjD0mf3 XfrfXhLt/JeA1HxVzUxviBThgJQ+9ik5sAKnrzM8= Date: Fri, 30 Aug 2024 17:59:02 -0700 From: Andrew Morton To: Zhu Jun Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] tools/mm: Use calloc and check the memory allocation failure Message-Id: <20240830175902.2cbdb98ed746001896f57fe5@linux-foundation.org> In-Reply-To: <20240829092144.5851-1-zhujun2@cmss.chinamobile.com> References: <20240829092144.5851-1-zhujun2@cmss.chinamobile.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam03 X-Rspam-User: X-Rspamd-Queue-Id: B91061C0009 X-Stat-Signature: 8jubkdbqhfmr33qhhy1pn3t77ix3dz1e X-HE-Tag: 1725065944-714825 X-HE-Meta: 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 arOu3bO5 /TCiAlEZOa0EC0EFBVqoa2QKP+IfY1YHWnqCgd/rUBGsAD6PmdpM1a601i0iOagbYLmDaj1rXGEXFK/WJM00L+FPCo+PkDHm6TB3nqVawiMM3Asra7jU4JLnPC+PyPXNhg9Y9AF33Scp4pJpHCjrggmEuFi91zPV7PoFEjO6HUEl+zH86SpotFlX1QfpEDxuaa6EjfHtbo+5Txjh1UbacrvBlvRhwedVtPJg/Sg1uJqp3oc4iuNBrb9sMmzrTleYrueBW2PcBHIy5jwXDqkk/nV1+hw== 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: List-Subscribe: List-Unsubscribe: On Thu, 29 Aug 2024 02:21:44 -0700 Zhu Jun wrote: > Replace malloc with calloc and add null pointer check > in case of allocation failure. > > ... > > --- a/tools/mm/page_owner_sort.c > +++ b/tools/mm/page_owner_sort.c > @@ -368,9 +368,10 @@ static __u64 get_ts_nsec(char *buf) > > static char *get_comm(char *buf) > { > - char *comm_str = malloc(TASK_COMM_LEN); > + char *comm_str = calloc(TASK_COMM_LEN, sizeof(char)); > > - memset(comm_str, 0, TASK_COMM_LEN); > + if (!comm_str) > + return NULL; It seems rather pointless doing this when the caller aren't coded to handle the NULL return. And really, for these little userspace tools it's OK for us to just assume that malloc() alway succeeds, isn't it?