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Wed, 9 Jun 2021 16:28:11 +0000 (GMT) Received: from b06wcsmtp001.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id E091EA4067; Wed, 9 Jun 2021 16:28:10 +0000 (GMT) Received: from ibm-vm (unknown [9.145.5.240]) by b06wcsmtp001.portsmouth.uk.ibm.com (Postfix) with ESMTP; Wed, 9 Jun 2021 16:28:10 +0000 (GMT) Date: Wed, 9 Jun 2021 18:28:09 +0200 From: Claudio Imbrenda To: Christoph Hellwig Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, linux-s390@vger.kernel.org, frankja@linux.ibm.com, borntraeger@de.ibm.com, cohuck@redhat.com, david@redhat.com, linux-mm@kvack.org, Andrew Morton , Nicholas Piggin , Uladzislau Rezki , Catalin Marinas , Thomas Gleixner , Ingo Molnar , David Rientjes Subject: Re: [PATCH v2 1/2] mm/vmalloc: export __vmalloc_node_range Message-ID: <20210609182809.7ae07aad@ibm-vm> In-Reply-To: References: <20210608180618.477766-1-imbrenda@linux.ibm.com> <20210608180618.477766-2-imbrenda@linux.ibm.com> Organization: IBM X-Mailer: Claws Mail 3.17.8 (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-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: 4dArTF9SgWQ2jROyRmRWPKChc48Cpmr7 X-Proofpoint-GUID: cxkj1UJfSeHbYCvHTev4n6QkkZuxq53h X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391,18.0.761 definitions=2021-06-09_04:2021-06-04,2021-06-09 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 phishscore=0 adultscore=0 bulkscore=0 priorityscore=1501 impostorscore=0 mlxlogscore=999 lowpriorityscore=0 malwarescore=0 clxscore=1015 suspectscore=0 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2104190000 definitions=main-2106090078 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 9 Jun 2021 16:59:17 +0100 Christoph Hellwig wrote: > On Tue, Jun 08, 2021 at 08:06:17PM +0200, Claudio Imbrenda wrote: > > The recent patches to add support for hugepage vmalloc mappings > > added a flag for __vmalloc_node_range to allow to request small > > pages. This flag is not accessible when calling vmalloc, the only > > option is to call directly __vmalloc_node_range, which is not > > exported. > > > > This means that a module can't vmalloc memory with small pages. > > > > Case in point: KVM on s390x needs to vmalloc a large area, and it > > needs to be mapped with small pages, because of a hardware > > limitation. > > > > This patch exports __vmalloc_node_range so it can be used in modules > > too. > > No. I spent a lot of effort to mak sure such a low-level API is > not exported. ok, but then how can we vmalloc memory with small pages from KVM?