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Wed, 10 Nov 2021 15:55:55 +0000 (GMT) Message-ID: Date: Wed, 10 Nov 2021 21:25:54 +0530 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.2.0 Subject: Re: [PATCH v4 2/3] mm/mempolicy: add set_mempolicy_home_node syscall Content-Language: en-US To: Jonathan Corbet , linux-mm@kvack.org Cc: akpm@linux-foundation.org, Ben Widawsky , Dave Hansen , Feng Tang , Michal Hocko , Andrea Arcangeli , Mel Gorman , Mike Kravetz , Randy Dunlap , Vlastimil Babka , Andi Kleen , Dan Williams , Huang Ying , linux-api@vger.kernel.org References: <20211101050206.549050-1-aneesh.kumar@linux.ibm.com> <20211101050206.549050-3-aneesh.kumar@linux.ibm.com> <871r3okpjh.fsf@meer.lwn.net> From: "Aneesh Kumar K.V" In-Reply-To: <871r3okpjh.fsf@meer.lwn.net> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: xsOoGOKCXADymWOh323nxMxnfdrvKHaT X-Proofpoint-GUID: L6SNECGRnExaZfBbJFaAaUIqIOttrayr X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.790,Hydra:6.0.425,FMLib:17.0.607.475 definitions=2021-11-10_05,2021-11-08_02,2020-04-07_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 suspectscore=0 mlxscore=0 spamscore=0 adultscore=0 lowpriorityscore=0 impostorscore=0 priorityscore=1501 clxscore=1011 mlxlogscore=999 bulkscore=0 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2110150000 definitions=main-2111100081 X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 16D91B0000B0 X-Stat-Signature: 81xqp4girezww6zgxsc4eksuajqsj3tc Authentication-Results: imf19.hostedemail.com; dkim=pass header.d=ibm.com header.s=pp1 header.b="Lqp/5fjK"; spf=pass (imf19.hostedemail.com: domain of aneesh.kumar@linux.ibm.com designates 148.163.156.1 as permitted sender) smtp.mailfrom=aneesh.kumar@linux.ibm.com; dmarc=pass (policy=none) header.from=ibm.com X-HE-Tag: 1636559764-80038 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 11/10/21 20:48, Jonathan Corbet wrote: > "Aneesh Kumar K.V" writes: > >> This syscall can be used to set a home node for the MPOL_BIND >> and MPOL_PREFERRED_MANY memory policy. Users should use this >> syscall after setting up a memory policy for the specified range >> as shown below. > > So I noticed one little thing as I was looking at this... > > [...] > >> +SYSCALL_DEFINE4(set_mempolicy_home_node, unsigned long, start, unsigned long, len, >> + unsigned long, home_node, unsigned long, flags) >> +{ >> + struct mm_struct *mm = current->mm; >> + struct vm_area_struct *vma; >> + struct mempolicy *new; >> + unsigned long vmstart; >> + unsigned long vmend; >> + unsigned long end; >> + int err = -ENOENT; >> + >> + if (start & ~PAGE_MASK) >> + return -EINVAL; >> + >> + len = (len + PAGE_SIZE - 1) & PAGE_MASK; >> + end = start + len; >> + >> + if (end < start) >> + return -EINVAL; >> + if (end == start) >> + return 0; >> + mmap_write_lock(mm); >> + vma = find_vma(mm, start); >> + for (; vma && vma->vm_start < end; vma = vma->vm_next) { >> + >> + vmstart = max(start, vma->vm_start); >> + vmend = min(end, vma->vm_end); >> + new = mpol_dup(vma_policy(vma)); >> + if (IS_ERR(new)) { >> + err = PTR_ERR(new); >> + break; >> + } >> + /* >> + * Only update home node if there is an existing vma policy >> + */ >> + if (!new) >> + continue; >> + new->home_node = home_node; >> + err = mbind_range(mm, vmstart, vmend, new); >> + if (err) >> + break; >> + } >> + mmap_write_unlock(mm); >> + return err; >> +} > > You never do anything with flags; I believe you want to check and ensure > that it's zero if there are no defined flags at this point? > > Will update that in v5. I guess EINVAL is the right error for flags != 0? -aneesh