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x-vs=clean score=-100 state=0 X-ME-VSCategory: clean Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753885AbeCUWyU (ORCPT ); Wed, 21 Mar 2018 18:54:20 -0400 Received: from aserp2130.oracle.com ([141.146.126.79]:55540 "EHLO aserp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753715AbeCUWyT (ORCPT ); Wed, 21 Mar 2018 18:54:19 -0400 Subject: Re: [PATCH v2] shm: add split function to shm_vm_ops To: Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Laurent Dufour , Michal Hocko , Dan Williams , Andrea Arcangeli , stable@vger.kernel.org References: <0d24f817-303a-7b4d-4603-b2d14e4b391a@oracle.com> <20180321161314.7711-1-mike.kravetz@oracle.com> <20180321135618.f3d4a0c30d9f413ce4092ddf@linux-foundation.org> From: Mike Kravetz Message-ID: <051fa302-f4c2-cc90-7a12-eaedfa806e73@oracle.com> Date: Wed, 21 Mar 2018 15:53:56 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.5.2 MIME-Version: 1.0 In-Reply-To: <20180321135618.f3d4a0c30d9f413ce4092ddf@linux-foundation.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=8839 signatures=668695 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1711220000 definitions=main-1803200127 Sender: stable-owner@vger.kernel.org X-Mailing-List: stable@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On 03/21/2018 01:56 PM, Andrew Morton wrote: > On Wed, 21 Mar 2018 09:13:14 -0700 Mike Kravetz wrote: >> >> +static int shm_split(struct vm_area_struct *vma, unsigned long addr) >> +{ >> + struct file *file = vma->vm_file; >> + struct shm_file_data *sfd = shm_file_data(file); >> + >> + if (sfd->vm_ops && sfd->vm_ops->split) >> + return sfd->vm_ops->split(vma, addr); > > This will be the only site which tests for NULL shm_file_data.vm_ops. > It's a can't-happen, methinks. You are correct, thanks for catching this. > > I think I'll leave it as it is for now and will queue up a non-urgent > patch: > > > > From: Andrew Morton > Subject: ipc/shm.c: shm_split(): remove unneeded test for NULL shm_file_data.vm_ops > > This was added by the recent "ipc/shm.c: add split function to > shm_vm_ops", but it is not necessary. > > Cc: Laurent Dufour > Cc: Dan Williams > Cc: Michal Hocko > Cc: Davidlohr Bueso > Cc: Manfred Spraul > Signed-off-by: Andrew Morton Looks good, FWIW Reviewed-by: Mike Kravetz -- Mike Kravetz > --- > > ipc/shm.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff -puN ipc/shm.c~ipc-shmc-shm_split-remove-unneeded-test-for-null-shm_file_datavm_ops ipc/shm.c > --- a/ipc/shm.c~ipc-shmc-shm_split-remove-unneeded-test-for-null-shm_file_datavm_ops > +++ a/ipc/shm.c > @@ -391,7 +391,7 @@ static int shm_split(struct vm_area_stru > struct file *file = vma->vm_file; > struct shm_file_data *sfd = shm_file_data(file); > > - if (sfd->vm_ops && sfd->vm_ops->split) > + if (sfd->vm_ops->split) > return sfd->vm_ops->split(vma, addr); > > return 0; > _ >