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Tue, 13 Oct 2026 13:31:11 +0000 (GMT) Received: from thinkpad-T15 (unknown [9.87.131.228]) by smtpav05.fra02v.mail.ibm.com (Postfix) with SMTP; Tue, 13 Oct 2026 13:31:11 +0000 (GMT) Date: Tue, 13 Oct 2026 15:31:09 +0200 From: Gerald Schaefer To: Alexander Gordeev Cc: Heiko Carstens , 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: <20261013153109.5d5143f6@thinkpad-T15> In-Reply-To: <964adeedfd20d4dbcc9a6341f57ec7aaac6c6adc.1791365932.git.agordeev@linux.ibm.com> References: <964adeedfd20d4dbcc9a6341f57ec7aaac6c6adc.1791365932.git.agordeev@linux.ibm.com> X-Mailer: Claws Mail 4.4.0 (GTK 3.24.52; x86_64-redhat-linux-gnu) 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-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-GUID: nbn6L9Ekh3ehchxzuRjBBJZzbONil6I2 X-Proofpoint-ORIG-GUID: _EMY1DVppaZqn56vCK9_9jqVJYlZCfvl X-Authority-Analysis: v=2.4 cv=aqInmiZV c=1 sm=1 tr=0 ts=6ace32a4 cx=c_pps a=bLidbwmWQ0KltjZqbj+ezA==:117 a=bLidbwmWQ0KltjZqbj+ezA==:17 a=kj9zAlcOel0A:10 a=660iZSQnnn4A:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=U7nrCbtTmkRpXpFmAIza:22 a=VnNF1IyMAAAA:8 a=mmsD3Eh6YA-KHFnkoBgA:9 a=CjuIK1q_8ugA:10 a=zZCYzV9kfG8A:10 X-Proofpoint-Spam-Info: AW1haW4tMjYxMDEzMDA1MiBTYWx0ZWRfX4602m6zcTb7e qnLVW5A8CULLZLaZsTQHpjdHHPNRkjITA3O4QcvhC9OxNWgcutb90Pbn+OcczOHivkFFCc4XTzP vf/qTWv/k/dcKvOJOsnC+DQt5KjrYzw= X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYxMDEzMDA1MiBTYWx0ZWRfX3Fny+U00kJZM hkCrydYS+YKWHg2EFbUCegrwD9C1TeQpoG9e2n2Px6hZ+4aPxLXZo2RxTgpuP17VgSe9rQwK8jq ztJtWhCdvwsXm7dsZLBluy+Kxljg5wWVMVVswfoXi8HTzHesLME09BVlOwFdXZLt0gp/SvDV6Qf L6o2mVak+nqIUgEOQD1Rs8EhFapELqUj0YWWjypFo5Sxplxkzm322MQQOxCeuPiAXxQNlUFNE+u Q+wCMRNPFnQbSNZijrZs4ZLpz3f60T5GJq3Rg+Iux5LZjScPmV5cbRFLY89o+K7qtU4YQHBa+HO vOMNjCqhJtqhrY8UIFZwEm3etl8+9TqkBgZwn/kvDZnARzdNlMJOhZlD/KdPM3X9SGKTtOOq9lg Q1TwgMYq/AhqmyUKIEQfmj9ywVXSdBsqQYZt5dA4BK4A+L9viv+EnOsuoX1dPYhHaLRD5qlxDWF 3YvIYUV4Kx51wq7UiLw== 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 phishscore=0 clxscore=1011 spamscore=0 malwarescore=0 suspectscore=0 bulkscore=0 adultscore=0 impostorscore=0 priorityscore=1501 lowpriorityscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2610080000 definitions=main-2610130052 On Wed, 7 Oct 2026 13:41:53 +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(-) Looks good to me. Reviewed-by: Gerald Schaefer