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[2003:cb:c70c:a600:1e3e:c75:d269:867a]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-38deb4f7bacsm2479965f8f.58.2025.02.12.10.14.53 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 12 Feb 2025 10:14:54 -0800 (PST) Message-ID: Date: Wed, 12 Feb 2025 19:14:52 +0100 Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [GIT PULL v2 09/20] KVM: s390: move pv gmap functions into kvm To: Claudio Imbrenda Cc: pbonzini@redhat.com, kvm@vger.kernel.org, linux-s390@vger.kernel.org, frankja@linux.ibm.com, borntraeger@de.ibm.com References: <20250131112510.48531-1-imbrenda@linux.ibm.com> <20250131112510.48531-10-imbrenda@linux.ibm.com> <20250212184538.3c79d608@p-imbrenda> From: David Hildenbrand Content-Language: en-US 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: <20250212184538.3c79d608@p-imbrenda> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 12.02.25 18:45, Claudio Imbrenda wrote: > On Wed, 12 Feb 2025 17:55:18 +0100 > David Hildenbrand wrote: > >> On 31.01.25 12:24, Claudio Imbrenda wrote: >>> Move gmap related functions from kernel/uv into kvm. >>> >>> Create a new file to collect gmap-related functions. >>> >>> Reviewed-by: Janosch Frank >>> Reviewed-by: Christoph Schlameuss >>> [fixed unpack_one(), thanks mhartmay@linux.ibm.com] >>> Link: https://lore.kernel.org/r/20250123144627.312456-6-imbrenda@linux.ibm.com >>> Signed-off-by: Claudio Imbrenda >>> Message-ID: <20250123144627.312456-6-imbrenda@linux.ibm.com> >>> --- >> >> This patch breaks large folio splitting because you end up un-refing >> the wrong folios after a split; I tried to make it work, but either >> because of other changes in this patch (or in others), I >> cannot get it to work and have to give up for today. > > yes, I had also noticed that and I already have a fix ready. In fact my > fix was exactly like yours, except that I did not pass the struct folio > anymore to kvm_s390_wiggle_split_folio(), but instead I only pass a > page and use page_folio() at the beginning, and I use > split_huge_page_to_list_to_order() directly instead of split_folio() > > unfortunately the fix does not fix the issue I'm seeing.... > > but putting printks everywhere seems to solve the issue, so it seems to > be a race somewhere It also doesn't work with a single vCPU for me. The VM is stuck in With a two vCPUs (so one can report the lockup), I get: [ 62.645168] rcu: INFO: rcu_sched self-detected stall on CPU [ 62.645181] rcu: 0-....: (5999 ticks this GP) idle=0104/1/0x4000000000000002 softirq=2/2 fqs=2997 [ 62.645186] rcu: (t=6000 jiffies g=-1199 q=62 ncpus=2) [ 62.645191] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.14.0-427.33.1.el9_4.s390x #1 [ 62.645194] Hardware name: IBM 3931 LA1 400 (KVM/Linux) [ 62.645195] Krnl PSW : 0704c00180000000 0000000024b3e776 (set_memory_decrypted+0x66/0xa0) [ 62.645206] R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:3 CC:0 PM:0 RI:0 EA:3 [ 62.645208] Krnl GPRS: 00000000ca004000 0000037f00000001 000000008092f000 0000000000000000 [ 62.645210] 0000037fffb1bbc0 0000000000000001 0000000025e75208 000000008092f000 [ 62.645211] 0000000080873808 0000037fffb1bcd8 0000000000001000 0000000025e75220 [ 62.645213] 0000000080281500 00000000258aa480 0000000024c0b17a 0000037fffb1bb20 [ 62.645220] Krnl Code: 0000000024b3e76a: a784000f brc 8,0000000024b3e788 [ 62.645220] 0000000024b3e76e: a7210fff tmll %r2,4095 [ 62.645220] #0000000024b3e772: a7740017 brc 7,0000000024b3e7a0 [ 62.645220] >0000000024b3e776: b9a40034 uvc %r3,%r4,0 [ 62.645220] 0000000024b3e77a: b2220010 ipm %r1 [ 62.645220] 0000000024b3e77e: 8810001c srl %r1,28 [ 62.645220] 0000000024b3e782: ec12fffa017e cij %r1,1,2,0000000024b3e776 [ 62.645220] 0000000024b3e788: a72b1000 aghi %r2,4096 [ 62.645232] Call Trace: [ 62.645234] [<0000000024b3e776>] set_memory_decrypted+0x66/0xa0 [ 62.645238] [<0000000024c0b17a>] dma_direct_alloc+0x16a/0x2d0 [ 62.645242] [<0000000024c09b92>] dma_alloc_attrs+0x62/0x80 [ 62.645243] [<000000002546c950>] cio_gp_dma_create+0x60/0xa0 [ 62.645248] [<0000000025ebb712>] css_bus_init+0x102/0x1b8 [ 62.645252] [<0000000025ebb7ea>] channel_subsystem_init+0x22/0xf8 [ 62.645254] [<0000000024b149ac>] do_one_initcall+0x3c/0x200 [ 62.645256] [<0000000025e777be>] do_initcalls+0x11e/0x148 [ 62.645260] [<0000000025e77a34>] kernel_init_freeable+0x1cc/0x208 [ 62.645262] [<00000000254ad01e>] kernel_init+0x2e/0x170 [ 62.645264] [<0000000024b16fdc>] __ret_from_fork+0x3c/0x60 [ 62.645266] [<00000000254bb07a>] ret_from_fork+0xa/0x40 The removed PTE lock would only explain it if we would have a concurrent GUP etc. from QEMU I/O ? Not sure. To fix the wrong refcount freezing, doing exactly what folio splitting does (migration PTEs, locking the pagecache etc., freezing->converting, removing migration ptes) should work, but requires a bit of work. -- Cheers, David / dhildenb