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b=jUDfUc7mEFZUX45qomM6RsYqoM/5CDi75b7/yyE4Z73kJovnvDmd/C8y4u1uj24dF ipBJjGLGPtR53JWmGj6U0tOIvgXHUDnwdse8EQsjVQofHFVhizI4f1CQnepNrgthao 2O7U1frt90PzjaFvpfA68R420ut+CTY5fKNVrsy8= Date: Tue, 28 Oct 2025 14:53:34 -0700 From: Andrew Morton To: Luiz Capitulino Cc: hca@linux.ibm.com, borntraeger@linux.ibm.com, joao.m.martins@oracle.com, mike.kravetz@oracle.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-s390@vger.kernel.org, gor@linux.ibm.com, gerald.schaefer@linux.ibm.com, agordeev@linux.ibm.com, osalvador@suse.de, david@redhat.com, aneesh.kumar@kernel.org Subject: Re: [PATCH v2] s390: fix HugeTLB vmemmap optimization crash Message-Id: <20251028145334.5a97211e0e46ca42fe2fa0d0@linux-foundation.org> In-Reply-To: <20251028211533.47694-1-luizcap@redhat.com> References: <20251028211533.47694-1-luizcap@redhat.com> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 29CDB160002 X-Stat-Signature: if535n1b8bmz7d4y3cyrrarthdkjfhcj X-Rspam-User: X-HE-Tag: 1761688417-818362 X-HE-Meta: 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 AlsJN+8F bSicv+4oem8Gd/+iFKWk/Qrg6PALs/w30MtGVZmbUW2j3b2B5NULjjhBEY8jqxFn6FWsXtEHwqeW3YOASgyAKMG14cFQHbn/DDiy7DEaBobzHbQyRdsxYyQwO/LHQAzAQYy2OELp8flmb2DCuKwvIzrgcCGIIqk/in0uhN+m9D1NDuSDRvTOme+DYEqjszPPiPEwKqa3SfTs8coyDfh3idVsGLov0X8cbbFDRhaIPddXBfSHYWpA3XmSKmKBscLCn9wYRX5nzhysMP2VB++i0v3MUzwyM6C5hnC1Gppk+o2rhOKg= 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 Tue, 28 Oct 2025 17:15:33 -0400 Luiz Capitulino wrote: > A reproducible crash occurs when enabling HugeTLB vmemmap optimization (HVO) > on s390. The crash and the proposed fix were worked on an s390 KVM guest > running on an older hypervisor, as I don't have access to an LPAR. However, > the same issue should occur on bare-metal. > > Reproducer (it may take a few runs to trigger): > > # sysctl vm.hugetlb_optimize_vmemmap=1 > # echo 1 > /proc/sys/vm/nr_hugepages > # echo 0 > /proc/sys/vm/nr_hugepages > > ... > > This commit fixes this by implementing flush_tlb_all() on s390 as an > alias to __tlb_flush_global(). This should cause a flush on all TLB > entries on all CPUs as expected by the flush_tlb_all() semantics. > > ... > > arch/s390/include/asm/tlbflush.h | 6 +++++- Thanks, I'll add this to mm.git. If s390 people prefer to merge it (or nack it!) then please do so and I'll drop the mm.git copy.