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Thu, 1 Oct 2026 15:41:18 +0000 (GMT) Received: from osiris (unknown [9.111.57.16]) by smtpav04.fra02v.mail.ibm.com (Postfix) with ESMTPS; Thu, 1 Oct 2026 15:41:18 +0000 (GMT) Date: Thu, 1 Oct 2026 17:41:17 +0200 From: Heiko Carstens To: Alexander Gordeev Cc: Gerald Schaefer , Christian Borntraeger , Vasily Gorbik , Claudio Imbrenda , Andrey Ryabinin , linux-s390@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com Subject: Re: [PATCH v7 2/4] s390/mm: Batch PTE updates in lazy MMU mode Message-ID: <20261001154117.23106Da3-hca@linux.ibm.com> References: <20260824104048.11040Cdc-hca@linux.ibm.com> <20261001082143.23106A21-hca@linux.ibm.com> <15c64970-d54e-4b8f-96f6-50c021079a94-agordeev@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <15c64970-d54e-4b8f-96f6-50c021079a94-agordeev@linux.ibm.com> X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Authority-Analysis: v=2.4 cv=FYWiV5+6 c=1 sm=1 tr=0 ts=6abe7f23 cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=kj9zAlcOel0A:10 a=660iZSQnnn4A:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=V8glGbnc2Ofi9Qvn3v5h:22 a=RQ3G99v50yCnU2VXwHMA:9 a=CjuIK1q_8ugA:10 X-Proofpoint-Spam-Info: AW1haW4tMjYxMDAxMDA2MiBTYWx0ZWRfX2z+LpBAEyxRt Kx/W8UWE7w2jOo30Q+6cHpEdD8uZAmx0VaxLB+mtqsnFJyO2ezeEbXoKplI2RbU/Ptc0LLSOnPe /WSGK4CzGEe0dS+Cl+hxbRUsl8VVTvQ= X-Proofpoint-ORIG-GUID: Z6UFw9oTZ0wEx_TlcRHvUidj7D5SDPbL X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYxMDAxMDA2MiBTYWx0ZWRfXx7MDApKeGV58 0BP7hn3rjnPlt/0FlyxvAXksOL8xH31JqwCL3UWGp/IIYm5vva+6MvbqZMUgt5hj9hmvqbTam6o PRhMR7Em+qwReoUjsf9DsqvO52ouGFG8whQMJR60fDxX3ZQO5FLwX9H5Dpe6sR3QFF/aDzjJFt0 drkfpq4Jgek9aeOz9h8iqP1H2TspssKiGVk0ngl+j+npyqu19IFHPiNHC/BPS+8Q6Ty7WcNTo3N tJz3yIkWyy8fcKr720w1fcygPPv5LyZa1xEHAnK+MZhdxQDpFvZm85cRdE216NtmapkrM7bDFqH LvK8INARMyax5cbwHzESfRzjtSBWJr95nCCH4OF8cLFPWKvH5zFlFBH9bUf99NjMLyYOswZUERg jB1Mi63JIhadfEXZFq6PxbAYU4L3NYvuEw/vE8KE5a38u7YftU4+3PJcHKNCx4mG+PjsL7ikWkr 5p6UhgIOBc64wtu3Stg== X-Proofpoint-GUID: _qdtfAZ6gAzJ0RjX8Ic6qXL6aF2Zt8nE X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-10-01_04,2026-09-21_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 adultscore=0 clxscore=1015 impostorscore=0 spamscore=0 phishscore=0 priorityscore=1501 malwarescore=0 bulkscore=0 lowpriorityscore=0 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2609040000 definitions=main-2610010062 On Thu, Oct 01, 2026 at 11:20:17AM +0200, Alexander Gordeev wrote: > On Thu, Oct 01, 2026 at 10:21:43AM +0200, Heiko Carstens wrote: > > On Thu, Oct 01, 2026 at 10:00:55AM +0200, Alexander Gordeev wrote: > > > On Mon, Aug 24, 2026 at 12:40:48PM +0200, Heiko Carstens wrote: > > Not really. But why is lazy_mmu_count 32 bit? Do you expect a nesting > > level of 2^32? :) If you would reduce that to one byte you could use > > tmy or cliy. > > Good point. But still, do you think it worth dropping the KASAN check? KASAN check for lowcore? I don't think we care - this is initialized to zero anyway, so what could go wrong? Also given how frequently these operations are used, yes, please drop KASAN checks.