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Tue, 13 Oct 2026 14:43:54 +0000 (GMT) Received: from osiris (unknown [9.111.34.214]) by smtpav07.fra02v.mail.ibm.com (Postfix) with ESMTPS; Tue, 13 Oct 2026 14:43:53 +0000 (GMT) Date: Tue, 13 Oct 2026 16:43:52 +0200 From: Heiko Carstens To: Alexander Gordeev Cc: Gerald Schaefer , Christian Borntraeger , Vasily Gorbik , Claudio Imbrenda , Andrey Ryabinin , Muhammad Usama Anjum , linux-s390@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com Subject: Re: [PATCH v8 10/15] s390/mm: Cleanup pXXp_flush_lazy() routines Message-ID: <20261013144352.128264A4e-hca@linux.ibm.com> References: <964adeedfd20d4dbcc9a6341f57ec7aaac6c6adc.1791365932.git.agordeev@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-s390@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: <964adeedfd20d4dbcc9a6341f57ec7aaac6c6adc.1791365932.git.agordeev@linux.ibm.com> X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Authority-Analysis: v=2.4 cv=Cr0q4X4D c=1 sm=1 tr=0 ts=6ace43af cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17 a=kj9zAlcOel0A:10 a=660iZSQnnn4A:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=iQ6ETzBq9ecOQQE5vZCe:22 a=VnNF1IyMAAAA:8 a=mmsD3Eh6YA-KHFnkoBgA:9 a=CjuIK1q_8ugA:10 a=zZCYzV9kfG8A:10 X-Proofpoint-GUID: oWaGvRRXTzXYQwvMlJ1EMK_XRD2gIlgd X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYxMDEzMDA1OCBTYWx0ZWRfX+nEyqHNkh3qz DhaVa3dj0ROQ6LabrhDVO5Vj99k2pMmy5SA3qr64Df3VgF/CCOKdIGjLZwGPbaDTvUPMjjhp6No lBqwFVJxB5w8x/M6AJ6J1GGay0MlXLCTEgJARo+vHtsPGRDbs3wYXDuSaYOM/EoeCBYkEyDsrso WnJQzSDnfOltaZNf7fz6jm+wydCfySmPKIYnzS2zmqz2w7A3MjOlfOD65HxBuKCA7VkVoObHTXu qS7vtD6cDHTNUZ+DFz5rDqtwGxjl1gzFsRM8ITuMHA5YJXGV+5u2edH9Ds5Y3M+TCCPcJb5VsRd 630mvLRM3Ue9GPD7ddXjoP1Hf5ltEdNYXLML/dZYckl8PiuJ63zUr2PUDQa5ynTz4jRGH9wmuHZ S68i3VBLZudoL3r0vs/LMiCuy2m0RAqYuNU6sIe049QCX02iibJFrKtpK/KFN0MqzwZ7/V7F/Le geE9ThbgH9xRgeLSkGQ== X-Proofpoint-Spam-Info: AW1haW4tMjYxMDEzMDA1OCBTYWx0ZWRfX+ebmIRF7WKZt Bp7b2U5kHDjmI8Pos8BLqth/8SogBIzeXk2haGwf+x0eQI20V8EaD77MijWUfnk4sYCKULYsbEG 7qzRI0T+esyLIHZKnYyB5Y+Ig8zRbv0= X-Proofpoint-ORIG-GUID: CQ313svkBdd2nH7F9syrZVINxu4jyakU 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=2026-10-13_01,2026-10-09_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 spamscore=0 adultscore=0 priorityscore=1501 suspectscore=0 malwarescore=0 clxscore=1011 impostorscore=0 lowpriorityscore=0 phishscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2610080000 definitions=main-2610130058 On Wed, Oct 07, 2026 at 01:41:53PM +0200, Alexander Gordeev wrote: > Avoid unnecessary pgtable entry read in ptep_flush_lazy() and > pmdp_flush_lazy() routines. Use the already obtained value of > a pgtable entry instead of dereferencing it again. > > It might appear that the optimized out second dereferencing happens > under mm_context_t::flush_count lock and therefore a race condition > is possible. However, both routines write invalid entry bits to the > pgtable entries and therefore no reader is allowed to interpret the > rest of the value afterwards. > > Signed-off-by: Alexander Gordeev > --- > arch/s390/mm/pgtable.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) Applied, thanks!