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[2003:cb:c745:2a00:d74a:a8c5:20b6:3ec3]) by smtp.gmail.com with ESMTPSA id s11-20020adfeccb000000b003316b38c625sm12583163wro.99.2023.11.27.08.58.52 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 27 Nov 2023 08:58:52 -0800 (PST) Message-ID: <18d06a3d-b75f-4ac9-8791-8391a3f60575@redhat.com> Date: Mon, 27 Nov 2023 17:58:51 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 4/5] s390/mm: implement MEM_PREPARE_ONLINE/MEM_FINISH_OFFLINE notifiers To: Sumanth Korikkar Cc: linux-mm , Andrew Morton , Oscar Salvador , Michal Hocko , "Aneesh Kumar K.V" , Anshuman Khandual , Gerald Schaefer , Alexander Gordeev , Heiko Carstens , Vasily Gorbik , linux-s390 , LKML References: <20231127082023.2079810-1-sumanthk@linux.ibm.com> <20231127082023.2079810-5-sumanthk@linux.ibm.com> From: David Hildenbrand Autocrypt: addr=david@redhat.com; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzSREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwZgEEwEIAEICGwMGCwkIBwMCBhUIAgkKCwQW AgMBAh4BAheAAhkBFiEEG9nKrXNcTDpGDfzKTd4Q9wD/g1oFAl8Ox4kFCRKpKXgACgkQTd4Q 9wD/g1oHcA//a6Tj7SBNjFNM1iNhWUo1lxAja0lpSodSnB2g4FCZ4R61SBR4l/psBL73xktp rDHrx4aSpwkRP6Epu6mLvhlfjmkRG4OynJ5HG1gfv7RJJfnUdUM1z5kdS8JBrOhMJS2c/gPf wv1TGRq2XdMPnfY2o0CxRqpcLkx4vBODvJGl2mQyJF/gPepdDfcT8/PY9BJ7FL6Hrq1gnAo4 3Iv9qV0JiT2wmZciNyYQhmA1V6dyTRiQ4YAc31zOo2IM+xisPzeSHgw3ONY/XhYvfZ9r7W1l pNQdc2G+o4Di9NPFHQQhDw3YTRR1opJaTlRDzxYxzU6ZnUUBghxt9cwUWTpfCktkMZiPSDGd KgQBjnweV2jw9UOTxjb4LXqDjmSNkjDdQUOU69jGMUXgihvo4zhYcMX8F5gWdRtMR7DzW/YE BgVcyxNkMIXoY1aYj6npHYiNQesQlqjU6azjbH70/SXKM5tNRplgW8TNprMDuntdvV9wNkFs 9TyM02V5aWxFfI42+aivc4KEw69SE9KXwC7FSf5wXzuTot97N9Phj/Z3+jx443jo2NR34XgF 89cct7wJMjOF7bBefo0fPPZQuIma0Zym71cP61OP/i11ahNye6HGKfxGCOcs5wW9kRQEk8P9 M/k2wt3mt/fCQnuP/mWutNPt95w9wSsUyATLmtNrwccz63XOwU0EVcufkQEQAOfX3n0g0fZz Bgm/S2zF/kxQKCEKP8ID+Vz8sy2GpDvveBq4H2Y34XWsT1zLJdvqPI4af4ZSMxuerWjXbVWb T6d4odQIG0fKx4F8NccDqbgHeZRNajXeeJ3R7gAzvWvQNLz4piHrO/B4tf8svmRBL0ZB5P5A 2uhdwLU3NZuK22zpNn4is87BPWF8HhY0L5fafgDMOqnf4guJVJPYNPhUFzXUbPqOKOkL8ojk CXxkOFHAbjstSK5Ca3fKquY3rdX3DNo+EL7FvAiw1mUtS+5GeYE+RMnDCsVFm/C7kY8c2d0G NWkB9pJM5+mnIoFNxy7YBcldYATVeOHoY4LyaUWNnAvFYWp08dHWfZo9WCiJMuTfgtH9tc75 7QanMVdPt6fDK8UUXIBLQ2TWr/sQKE9xtFuEmoQGlE1l6bGaDnnMLcYu+Asp3kDT0w4zYGsx 5r6XQVRH4+5N6eHZiaeYtFOujp5n+pjBaQK7wUUjDilPQ5QMzIuCL4YjVoylWiBNknvQWBXS lQCWmavOT9sttGQXdPCC5ynI+1ymZC1ORZKANLnRAb0NH/UCzcsstw2TAkFnMEbo9Zu9w7Kv AxBQXWeXhJI9XQssfrf4Gusdqx8nPEpfOqCtbbwJMATbHyqLt7/oz/5deGuwxgb65pWIzufa N7eop7uh+6bezi+rugUI+w6DABEBAAHCwXwEGAEIACYCGwwWIQQb2cqtc1xMOkYN/MpN3hD3 AP+DWgUCXw7HsgUJEqkpoQAKCRBN3hD3AP+DWrrpD/4qS3dyVRxDcDHIlmguXjC1Q5tZTwNB boaBTPHSy/Nksu0eY7x6HfQJ3xajVH32Ms6t1trDQmPx2iP5+7iDsb7OKAb5eOS8h+BEBDeq 3ecsQDv0fFJOA9ag5O3LLNk+3x3q7e0uo06XMaY7UHS341ozXUUI7wC7iKfoUTv03iO9El5f XpNMx/YrIMduZ2+nd9Di7o5+KIwlb2mAB9sTNHdMrXesX8eBL6T9b+MZJk+mZuPxKNVfEQMQ a5SxUEADIPQTPNvBewdeI80yeOCrN+Zzwy/Mrx9EPeu59Y5vSJOx/z6OUImD/GhX7Xvkt3kq Er5KTrJz3++B6SH9pum9PuoE/k+nntJkNMmQpR4MCBaV/J9gIOPGodDKnjdng+mXliF3Ptu6 3oxc2RCyGzTlxyMwuc2U5Q7KtUNTdDe8T0uE+9b8BLMVQDDfJjqY0VVqSUwImzTDLX9S4g/8 kC4HRcclk8hpyhY2jKGluZO0awwTIMgVEzmTyBphDg/Gx7dZU1Xf8HFuE+UZ5UDHDTnwgv7E th6RC9+WrhDNspZ9fJjKWRbveQgUFCpe1sa77LAw+XFrKmBHXp9ZVIe90RMe2tRL06BGiRZr jPrnvUsUUsjRoRNJjKKA/REq+sAnhkNPPZ/NNMjaZ5b8Tovi8C0tmxiCHaQYqj7G2rgnT0kt WNyWQQ== Organization: Red Hat In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 0009018000F X-Stat-Signature: s3rgcao6gtn8rcnxsz6cqtmf4ngz7fry X-Rspam-User: X-HE-Tag: 1701104337-464103 X-HE-Meta: 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 mHMNRN8S 1x0jw9nqTTX7zTNlv5BbbZ8iwjiZoauzQuPDRgiXrwRS+Q9bIK72RTyWmWgVbi3rUEKpWtvMar3x28tl3gEdrd+ckjVQMvILzlX21593hRZnzgsT2wpcm1MFeVsDHV+JCMZWjIyo7dE/WjA2CzFs8Wlp8b1xJ+HnAUIS6gc7DLO5kdwQ8TNhg8iaNVvkKQtqHHuNd25neRLDWcLc4Hypo1dkwnKrbkqGIXaitPEO6SyeT2s0T2I3jvpdG1oKSwFYbBKm5PL7yozalh8SIDaCdFrdBAItdLjEO38BelygJLc0cyAugXKuw45t2rZ+iFCQsI1nmfIj4sBXpZ+k7cvrJ53HkrHytArIDNkeiPnsegYZs1In1yQU1DaqC2J4xuYjHPVnCggNJup4skRuZj/P04hdPt+IDVCjomMVYaHJnmtiu1GFcOHtuj9wSHWIf3QsXPtltVJlb/3XgeN3IMW9YvSOjig== 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 27.11.23 17:12, Sumanth Korikkar wrote: > On Mon, Nov 27, 2023 at 04:11:05PM +0100, David Hildenbrand wrote: >>> diff --git a/drivers/s390/char/sclp_cmd.c b/drivers/s390/char/sclp_cmd.c >>> index 355e63e44e95..30b829e4c052 100644 >>> --- a/drivers/s390/char/sclp_cmd.c >>> +++ b/drivers/s390/char/sclp_cmd.c >>> @@ -18,6 +18,7 @@ >>> #include >>> #include >>> #include >>> +#include >>> #include >>> #include >>> #include >>> @@ -26,6 +27,7 @@ >>> #include >>> #include >>> #include >>> +#include >>> #include "sclp.h" >>> @@ -319,6 +321,7 @@ static bool contains_standby_increment(unsigned long start, unsigned long end) >>> static int sclp_mem_notifier(struct notifier_block *nb, >>> unsigned long action, void *data) >>> { >>> + struct memory_block *memory_block; >>> unsigned long start, size; >>> struct memory_notify *arg; >>> unsigned char id; >>> @@ -340,18 +343,29 @@ static int sclp_mem_notifier(struct notifier_block *nb, >>> if (contains_standby_increment(start, start + size)) >>> rc = -EPERM; >>> break; >>> - case MEM_GOING_ONLINE: >>> + case MEM_PREPARE_ONLINE: >>> + memory_block = find_memory_block(pfn_to_section_nr(arg->start_pfn)); >>> + if (!memory_block) { >>> + rc = -EINVAL; >>> + goto out; >>> + } >>> rc = sclp_mem_change_state(start, size, 1); >>> + if (rc || !memory_block->altmap) >>> + goto out; >>> + /* >>> + * Set CMMA state to nodat here, since the struct page memory >>> + * at the beginning of the memory block will not go through the >>> + * buddy allocator later. >>> + */ >>> + __arch_set_page_nodat((void *)__va(start), memory_block->altmap->free); >> >> Looking up the memory block and grabbing the altmap from there is a bit >> unfortunate. >> >> Why can't we do that when adding the altmap? Will the hypervisor scream at >> us? >> > calling __arch_set_page_nodat() before making memory block accessible > will lead to crash. Hence, we think this is the only safe location to > place it. > >> ... would we want to communicate any altmap start+size via the memory >> notifier instead? > > Passing start, size of memory range via memory notifier looks correct > approach to me, as we try to make the specified range accessible. > > If we want to pass altmap size (nr_vmemmap_pages), then we might need a > new field in struct memory_notify, which would prevent access of > memory_block->altmap->free in the notifier. > > Do you want to take this approach instead? > > If yes, Then I could add a new field nr_vmemmap_pages in struct > memory_notify and place it in PATCH : introduce > MEM_PREPARE_ONLINE/MEM_FINISH_OFFLINE notifiers. Yes, see my other mail. That's probably cleanest! -- Cheers, David / dhildenb