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Tue, 1 Sep 2026 11:21:03 +0000 (GMT) Date: Tue, 1 Sep 2026 13:21:02 +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: <20260901112102.14482D13-hca@linux.ibm.com> References: <20260824104048.11040Cdc-hca@linux.ibm.com> <73a0a916-b39f-4ebe-bffe-448928b13bef-agordeev@linux.ibm.com> <20260826130257.21444B1a-hca@linux.ibm.com> <87a3147f-e993-4629-b0dd-a54aefbf20b1-agordeev@linux.ibm.com> <20260827081156.3869103Abc-hca@linux.ibm.com> <75462b8e-b190-4870-8fd6-22d1e4d89139-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: <75462b8e-b190-4870-8fd6-22d1e4d89139-agordeev@linux.ibm.com> X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-GUID: 8K80PWE4BSGNUh7vQEJ7XHJuKPzIopSE X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwOTAxMDA5OCBTYWx0ZWRfX/RVZH3fDICCj YynxObUK9vNEVHf1kEVw77bP+bjk1OPuuwG/O29XxMhIQf3dGXinc9fkc0gzBQGajvv1Ob3sjAS 9GPGqhUiG9ENdtMV2zR5q/0PK76uQBp2HhkYfmPLc9oTeqCDo0X8vX728bdRW57ZHYiRpw2l9Uw nz6fjK5AmQ+q5Z92RYB5ARR7f8OiqLhnYflXIkTV+vauVN/zUK54hSk3RRXIbqALCmrZQAL8FbI JCwrrGywv2nFcKW2GkItqAehIVz/mmxnxCcSvCzzrW4iGedUey0x2pq+Ufr+abZGAIhQnq29kxh 6PRJ7S5POzqw/JWvwNyzNG5K4TC00WkUKeexPQDxeT98XRGJ+Sh8rSEaCxV2PTFDyYFy/X5Rwzb U2KLwF8nwJ4uY6GSDX+/ADgn/S5cQ07Ni8fbWs7/sAZzYMx5/iVIV8v8aHa2dWeECPK7w2cmqY/ IgYY8OqGAsE8hgW+oKQ== X-Proofpoint-ORIG-GUID: QszmyM0FmfdQgEtsEdyezOdFzxTVE8Fa X-Proofpoint-Spam-Info: AW1haW4tMjYwOTAxMDA5OCBTYWx0ZWRfX7N6H8yy3IiB3 3YVTKkNiTFkfuvGy1w+TeO9feRDt+aIgK49vL4ApYUtR3Lu3Kyf7J+DRCcx3q86vgxeDd4jkY7R 2xVQdbS1v7oC+xdaoAFDNii1RWXtlxQ= X-Authority-Analysis: v=2.4 cv=B92JFutM c=1 sm=1 tr=0 ts=6a96b524 cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17 a=kj9zAlcOel0A:10 a=VdqzKS8jKosA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=V8glGbnc2Ofi9Qvn3v5h:22 a=ZNJKDMMrlkbq0tKfwxIA:9 a=CjuIK1q_8ugA:10 a=zZCYzV9kfG8A:10 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=2026-09-01_03,2026-08-31_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 adultscore=0 spamscore=0 clxscore=1015 suspectscore=0 phishscore=0 lowpriorityscore=0 bulkscore=0 priorityscore=1501 impostorscore=0 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2609010098 On Tue, Sep 01, 2026 at 01:16:58PM +0200, Alexander Gordeev wrote: > On Thu, Aug 27, 2026 at 01:40:01PM +0200, Alexander Gordeev wrote: > > On Thu, Aug 27, 2026 at 10:11:56AM +0200, Heiko Carstens wrote: > > > Imho the "final" version should either be implemented that it can go > > > without disabling bottom halves, or, if that is not worth the effort, > > > even disable interrupts, just to avoid other surprises. > > > > Yes, that would be the last resort. > > So leaving local_bh_enable|disable() while adding VM_BUG_ON(in_hardirq()) > could actually work. > > Also, I do not see how the code could be rearranged to avoid BH disable. Ok, then let's move forward with the current implementation. Thanks for looking into this!