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Tue, 28 Oct 2025 14:14:47 -0700 (PDT) X-Google-Smtp-Source: AGHT+IE8D9LTgZgrHHdWeOYc+DL8B2sdCN5Uw6C+NWfSsJhoUGyXAHdeOuejLijrW6CXCNixE1Fy2g== X-Received: by 2002:a05:620a:192a:b0:7f7:8271:1a77 with SMTP id af79cd13be357-8a8e426cda9mr126337685a.13.1761686086724; Tue, 28 Oct 2025 14:14:46 -0700 (PDT) Received: from [192.168.2.110] ([70.49.125.126]) by smtp.gmail.com with ESMTPSA id af79cd13be357-89f254a297dsm929505785a.28.2025.10.28.14.14.45 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 28 Oct 2025 14:14:46 -0700 (PDT) Message-ID: <5cc06269-5a6e-4874-bf68-fa4790f22bc2@redhat.com> Date: Tue, 28 Oct 2025 17:14:35 -0400 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm: hugetlb: fix HVO crash on s390 To: Heiko Carstens Cc: Joao Martins , osalvador@suse.de, akpm@linux-foundation.org, david@redhat.com, aneesh.kumar@kernel.org, borntraeger@linux.ibm.com, mike.kravetz@oracle.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-s390@vger.kernel.org, Vasily Gorbik , Gerald Schaefer , Alexander Gordeev References: <20251028153930.37107-1-luizcap@redhat.com> <50d815a1-8384-4eaa-8515-19d6c92425b3@oracle.com> <20251028161426.35377Af6-hca@linux.ibm.com> <5c72e064-9298-490e-b05a-16be6b5590b7@oracle.com> <20251028170251.11688Aa3-hca@linux.ibm.com> <4f522b65-1ab8-4725-8da7-3f071e7919c1@redhat.com> <20251028193708.7213A7e-hca@linux.ibm.com> From: Luiz Capitulino In-Reply-To: <20251028193708.7213A7e-hca@linux.ibm.com> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: oe2Rx7rKp5jadQiaeGMuPuH4LggjRUfpkF7EwRaLPhI_1761686087 X-Mimecast-Originator: redhat.com Content-Language: en-US, en-CA Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Stat-Signature: swukdc4obrjpzht43z5b1abbbg75eojn X-Rspamd-Queue-Id: C946B180002 X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1761686089-446 X-HE-Meta: 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 5RPnmezJ yHDXpmvDekhYhcZ6rksBHY5fvEiozfTtU+H+P1gIoy0KIm0VkUWbN9b6ISN3kkzO3na943/VjUMVfdsxjzEPe18ly3D7vjswNz2xcjvApWWQz+K3pW6tMBms2SKaL0h54BucfINxY4RWlJfg= 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 2025-10-28 15:37, Heiko Carstens wrote: > On Tue, Oct 28, 2025 at 01:15:57PM -0400, Luiz Capitulino wrote: >>>> flush_tlb_all() however is the *closest* equivalent to this that's behind an >>>> arch generic API i.e. flushing kernel address space on all CPUs TLBs. IIUC, x86 >>>> when doing flush_tlb_kernel_range with enough pages it switches to flush_tlb_all >>>> (these days on modern AMDs it's even one instruction solely in the calling CPU). >>> >>> Considering that flush_tlb_all() should be mapped to __tlb_flush_global() >>> and not __tlb_flush_kernel() on s390. >> >> You're right. >> >>> However if there is only a need to flush tlb entries for the complete(?) >>> kernel address space, then I'd rather propose a new tlb_flush_kernel() >>> instead of a big hammer. If I'm not mistaken flush_tlb_kernel_range() >>> exists for just avoiding that. And if architectures can avoid a global >>> flush of _all_ tlb entries then that should be made possible. >> >> Should we take a v2 doing your suggestion above for now and work on >> the tlb_flush_kernel() idea as a follow up improvement? At least we >> go from crashing to flushing more than we should... > > That's of course fine. I guess for stable backports a small fix is the > best way forward anyway. Exactly. I'll also see if I can find time to explore your API improvement suggestion. I'll send v2 shortly.