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Tue, 20 Jun 2023 13:14:46 GMT Received: from smtpav02.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 2135720040; Tue, 20 Jun 2023 13:14:46 +0000 (GMT) Received: from smtpav02.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 53CFC20043; Tue, 20 Jun 2023 13:14:42 +0000 (GMT) Received: from tarunpc (unknown [9.199.157.25]) by smtpav02.fra02v.mail.ibm.com (Postfix) with ESMTPS; Tue, 20 Jun 2023 13:14:42 +0000 (GMT) From: Tarun Sahu To: Vishal Verma , "Rafael J. Wysocki" , Len Brown , Andrew Morton , David Hildenbrand , Oscar Salvador , Dan Williams , Dave Jiang Cc: linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, nvdimm@lists.linux.dev, linux-cxl@vger.kernel.org, Huang Ying , Dave Hansen , Vishal Verma , aneesh.kumar@linux.ibm.com Subject: Re: [PATCH 3/3] dax/kmem: Always enroll hotplugged memory for memmap_on_memory In-Reply-To: <20230613-vv-kmem_memmap-v1-3-f6de9c6af2c6@intel.com> References: <20230613-vv-kmem_memmap-v1-0-f6de9c6af2c6@intel.com> <20230613-vv-kmem_memmap-v1-3-f6de9c6af2c6@intel.com> Date: Tue, 20 Jun 2023 18:44:40 +0530 Message-ID: <87zg4uwa0v.fsf@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: k445iHDRACRzPCIxEzPCR5_a3eK4s88q X-Proofpoint-GUID: uz0hnxRkr9FUlWfHMTCrnrTx7dGX1Mqi X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.254,Aquarius:18.0.957,Hydra:6.0.591,FMLib:17.11.176.26 definitions=2023-06-20_09,2023-06-16_01,2023-05-22_02 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 adultscore=0 mlxscore=0 suspectscore=0 lowpriorityscore=0 impostorscore=0 mlxlogscore=999 phishscore=0 malwarescore=0 bulkscore=0 clxscore=1011 spamscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2305260000 definitions=main-2306200117 X-Rspam-User: X-Stat-Signature: kkf9fhq9x99gc45uzftxkkipn49ebs6o X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: C6353140023 X-HE-Tag: 1687266902-960737 X-HE-Meta: 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 mpPHO6+c fIT1oenWpLbZxlaQQ255CbfCoSBjlJZosIoxO1KkE6vvJSpCTta33dnCR399H8/LDJJy3N9yVZas3Iizx9dPzEpG5PrdrAhOiAW2MfIeq3ZdW7arT4mENWiXCTqR37U6Qqjiw4t6OM+rPHNbScZCuKuqJZbz1gx2YLSZBNcisYmO6/n0XKIOv8LRhOb7x2RMPOJ+OK3mnUc6O8i30+Jx9T9YnYS7x/Lb6qG488TQa6IJ+2B0I9PEqgkI+vRhd95WGQkTejvByBfd3uIWWE8yBR+Ikpe6xuyO4L8BzxYn2PA4S3NA= 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: Hi Vishal, Vishal Verma writes: > With DAX memory regions originating from CXL memory expanders or > NVDIMMs, the kmem driver may be hot-adding huge amounts of system memory > on a system without enough 'regular' main memory to support the memmap > for it. To avoid this, ensure that all kmem managed hotplugged memory is > added with the MHP_MEMMAP_ON_MEMORY flag to place the memmap on the > new memory region being hot added. > Some architectures doesn't have support for MEMMAP_ON_MEMORY, bypassing the check mhp_memmap_on_memory() might cause problems on such architectures (for e.g PPC64). > To do this, call add_memory() in chunks of memory_block_size_bytes() as > that is a requirement for memmap_on_memory. Additionally, Use the > mhp_flag to force the memmap_on_memory checks regardless of the > respective module parameter setting. > > Cc: "Rafael J. Wysocki" > Cc: Len Brown > Cc: Andrew Morton > Cc: David Hildenbrand > Cc: Oscar Salvador > Cc: Dan Williams > Cc: Dave Jiang > Cc: Dave Hansen > Cc: Huang Ying > Signed-off-by: Vishal Verma > --- > drivers/dax/kmem.c | 49 ++++++++++++++++++++++++++++++++++++------------- > 1 file changed, 36 insertions(+), 13 deletions(-) > > diff --git a/drivers/dax/kmem.c b/drivers/dax/kmem.c > index 7b36db6f1cbd..0751346193ef 100644 > --- a/drivers/dax/kmem.c > +++ b/drivers/dax/kmem.c > @@ -12,6 +12,7 @@ > #include > #include > #include > +#include > #include "dax-private.h" > #include "bus.h" > > @@ -105,6 +106,7 @@ static int dev_dax_kmem_probe(struct dev_dax *dev_dax) > data->mgid = rc; > > for (i = 0; i < dev_dax->nr_range; i++) { > + u64 cur_start, cur_len, remaining; > struct resource *res; > struct range range; > > @@ -137,21 +139,42 @@ static int dev_dax_kmem_probe(struct dev_dax *dev_dax) > res->flags = IORESOURCE_SYSTEM_RAM; > > /* > - * Ensure that future kexec'd kernels will not treat > - * this as RAM automatically. > + * Add memory in chunks of memory_block_size_bytes() so that > + * it is considered for MHP_MEMMAP_ON_MEMORY > + * @range has already been aligned to memory_block_size_bytes(), > + * so the following loop will always break it down cleanly. > */ > - rc = add_memory_driver_managed(data->mgid, range.start, > - range_len(&range), kmem_name, MHP_NID_IS_MGID); > + cur_start = range.start; > + cur_len = memory_block_size_bytes(); > + remaining = range_len(&range); > + while (remaining) { > + mhp_t mhp_flags = MHP_NID_IS_MGID; > > - if (rc) { > - dev_warn(dev, "mapping%d: %#llx-%#llx memory add failed\n", > - i, range.start, range.end); > - remove_resource(res); > - kfree(res); > - data->res[i] = NULL; > - if (mapped) > - continue; > - goto err_request_mem; > + if (mhp_supports_memmap_on_memory(cur_len, > + MHP_MEMMAP_ON_MEMORY)) > + mhp_flags |= MHP_MEMMAP_ON_MEMORY; > + /* > + * Ensure that future kexec'd kernels will not treat > + * this as RAM automatically. > + */ > + rc = add_memory_driver_managed(data->mgid, cur_start, > + cur_len, kmem_name, > + mhp_flags); > + > + if (rc) { > + dev_warn(dev, > + "mapping%d: %#llx-%#llx memory add failed\n", > + i, cur_start, cur_start + cur_len - 1); > + remove_resource(res); > + kfree(res); > + data->res[i] = NULL; > + if (mapped) > + continue; > + goto err_request_mem; > + } > + > + cur_start += cur_len; > + remaining -= cur_len; > } > mapped++; > } > > -- > 2.40.1