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Thu, 6 Nov 2025 04:51:41 GMT Received: from smtpav06.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 783892004B; Thu, 6 Nov 2025 04:51:41 +0000 (GMT) Received: from smtpav06.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id AAE3A20049; Thu, 6 Nov 2025 04:51:37 +0000 (GMT) Received: from li-4f5ba44c-27d4-11b2-a85c-a08f5b49eada.in.ibm.com (unknown [9.109.204.116]) by smtpav06.fra02v.mail.ibm.com (Postfix) with ESMTP; Thu, 6 Nov 2025 04:51:37 +0000 (GMT) From: Sourabh Jain To: linux-kernel@vger.kernel.org Cc: Sourabh Jain , Aditya Gupta , Andrew Morton , Baoquan he , Dave Young , Hari Bathini , Jiri Bohac , Madhavan Srinivasan , Mahesh J Salgaonkar , Pingfan Liu , "Ritesh Harjani (IBM)" , Shivang Upadhyay , Vivek Goyal , linuxppc-dev@lists.ozlabs.org, kexec@lists.infradead.org Subject: [PATCH v2 5/5] crash: export crashkernel CMA reservation to userspace Date: Thu, 6 Nov 2025 10:21:07 +0530 Message-ID: <20251106045107.17813-6-sourabhjain@linux.ibm.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20251106045107.17813-1-sourabhjain@linux.ibm.com> References: <20251106045107.17813-1-sourabhjain@linux.ibm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: oy27WJyoVf45d-2LYhmnWv46AmUci0rC X-Proofpoint-GUID: bhah8pCo5NneVwQiOxlrQKOSrzEtVPK- X-Authority-Analysis: v=2.4 cv=SqidKfO0 c=1 sm=1 tr=0 ts=690c2962 cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=6UeiqGixMTsA:10 a=VkNPw1HP01LnGYTKEx00:22 a=VnNF1IyMAAAA:8 a=Z4Rwk6OoAAAA:8 a=20KFwNOVAAAA:8 a=pGLkceISAAAA:8 a=voM4FWlXAAAA:8 a=JfrnYn6hAAAA:8 a=JDx1kcstoNt1si94OFQA:9 a=HkZW87K1Qel5hWWM3VKY:22 a=IC2XNlieTeVoXbcui8wp:22 a=1CNFftbPRP8L7MoqJWF3:22 a=cPQSjfK2_nFv0Q5t_7PE:22 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUxMTAxMDAwOSBTYWx0ZWRfXwCcKGiv9l+zk G3FMJjzZrOWIYCtDyBfdjH+GpMX8ULeqFjgenl1Y1AvC5LwLZK/aKjSjjeMzftRTBQd8OIvI5Ur sjfggqm2SqG0rmD6t5g37WLrtZoaWyLTaWDbCxo+J2uQi5S6Yp3JV9rnmEvO6yjXWIZ50NQ1xGa MJ1cV2BhVnXcNPIN/zBO1N1/bFejR2kezioimG7Bt0BKDTRpDfpqRq3SH9XVaOSaMLF8Aqou1c5 7n4osxcATVfghVZVmPSNrZMBoOSzu+eDrGYLFsHEZIAF1b304eCn997xRixGk3YaJ9u6AhbxDgL WJDgbIm9qPkRoStDXaQ18k5LNOdO23+HnWmZXnv3RCjmWk2/i0GETP+Nw0K5Tvi6FMMuQN4GbtI lJI/k8CcXLAvJ3QI447Wzs8YTO7zGw== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.9,FMLib:17.12.100.49 definitions=2025-11-05_09,2025-11-03_03,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 clxscore=1015 impostorscore=0 adultscore=0 lowpriorityscore=0 malwarescore=0 spamscore=0 priorityscore=1501 bulkscore=0 phishscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2510240000 definitions=main-2511010009 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20251105_205147_911905_FD1FFB8F X-CRM114-Status: GOOD ( 14.57 ) X-BeenThere: kexec@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "kexec" Errors-To: kexec-bounces+kexec=archiver.kernel.org@lists.infradead.org Add a sysfs entry /sys/kernel/kexec/crash_cma_ranges to expose all CMA crashkernel ranges. This allows userspace tools configuring kdump to determine how much memory is reserved for crashkernel. If CMA is used, tools can warn users when attempting to capture user pages with CMA reservation. The new sysfs hold the CMA ranges in below format: cat /sys/kernel/kexec/crash_cma_ranges 100000000-10c7fffff Cc: Aditya Gupta Cc: Andrew Morton Cc: Baoquan he Cc: Dave Young Cc: Hari Bathini Cc: Jiri Bohac Cc: Madhavan Srinivasan Cc: Mahesh J Salgaonkar Cc: Pingfan Liu Cc: Ritesh Harjani (IBM) Cc: Shivang Upadhyay Cc: Vivek Goyal Cc: linuxppc-dev@lists.ozlabs.org Cc: kexec@lists.infradead.org Signed-off-by: Sourabh Jain --- Documentation/ABI/testing/sysfs-kernel-kexec-kdump | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/Documentation/ABI/testing/sysfs-kernel-kexec-kdump b/Documentation/ABI/testing/sysfs-kernel-kexec-kdump index 00c00f380fea..f59051b5d96d 100644 --- a/Documentation/ABI/testing/sysfs-kernel-kexec-kdump +++ b/Documentation/ABI/testing/sysfs-kernel-kexec-kdump @@ -49,3 +49,13 @@ Description: read only is used by the user space utility kexec to support updating the in-kernel kdump image during hotplug operations. User: Kexec tools + +What: /sys/kernel/kexec/crash_cma_ranges +Date: Nov 2025 +Contact: kexec@lists.infradead.org +Description: read only + Provides information about the memory ranges reserved from + the Contiguous Memory Allocator (CMA) area that are allocated + to the crash (kdump) kernel. It lists the start and end physical + addresses of CMA regions assigned for crashkernel use. +User: kdump service -- 2.51.0