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Wed, 20 May 2026 14:48:58 +0000 (GMT) Received: from [9.52.200.195] (unknown [9.52.200.195]) by smtpav05.fra02v.mail.ibm.com (Postfix) with ESMTP; Wed, 20 May 2026 14:48:58 +0000 (GMT) Message-ID: <4767d529-4551-43d4-8190-04edd559fff2@linux.ibm.com> Date: Wed, 20 May 2026 16:48:58 +0200 Precedence: bulk X-Mailing-List: sashiko@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v14 03/19] unwind_user/sframe: Store .sframe section data in per-mm maple tree To: Steven Rostedt Cc: Josh Poimboeuf , bpf@vger.kernel.org, sashiko@lists.linux.dev, Indu Bhagat , Chris Mason , Roman Gushchin References: <20260505121718.3572346-4-jremus@linux.ibm.com> <20260505185158.39F35C2BCB4@smtp.kernel.org> <49318ed5-8668-43fe-880d-b91bd7c3a7a9@linux.ibm.com> <20260506112135.554ca88c@fedora> Content-Language: en-US From: Jens Remus Organization: IBM Deutschland Research & Development GmbH In-Reply-To: <20260506112135.554ca88c@fedora> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTIwMDE0MiBTYWx0ZWRfX1y2PGzN8S6lj FEkxSgKgD3GpIvHzHuq9gUJZeEtViKSamTCUmpHFQqgH1hk5L+exQJYn0EO04KtAFqUFeOrAu6A IQlWqOoLACzl4Qs4KXCbFcMTuPQP/KgG0kIxfySvQwhaeU9bcF6N9GzjUqG8jFQ1VSkp9mIXFYb LViHMTBLbF6BZhu09VGwZAF6LpwS1c/exUoXYDXMH+B1JZgOUFapn+8u6TfQ4VJxnByf64yRCgU cYPiYwhyKur3FzUAHfrbTAQLMPn+WtUS6LCRGRL0uOo1UXbcmXqJpmxCMlg+Kyn2i9TGwtx06o7 o4X+auNTQ0W4tV0Zh5iw2WzS5KWdsSEKBMQt/uPksPK55WwTiT7zrH5NSfJca9SRFXlK2CiZ8iS mV4SjlM1mkLzAhy1GeKU2mynuspV47NWKc1/1LpfmrT4qoOpYFlf+iDHOgRE8j98qyyknoDJo10 QhvAYqxIeD1o6cg1hCQ== X-Authority-Analysis: v=2.4 cv=BNuDalQG c=1 sm=1 tr=0 ts=6a0dc9de cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=IkcTkHD0fZMA:10 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=iQ6ETzBq9ecOQQE5vZCe:22 a=VnNF1IyMAAAA:8 a=sYNHCNsufd3psUy7vJEA:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 X-Proofpoint-ORIG-GUID: OG591AqKXtBPSiihZllHHGG11PjzUYrO X-Proofpoint-GUID: 4j-K5WuoIhvTnf28zPkClXWznTwMsY1q X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-05-20_02,2026-05-18_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 adultscore=0 priorityscore=1501 malwarescore=0 impostorscore=0 suspectscore=0 lowpriorityscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1011 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2605130000 definitions=main-2605200142 On 5/6/2026 5:21 PM, Steven Rostedt wrote: > On Wed, 6 May 2026 15:50:45 +0200 > Jens Remus wrote: >>> [ ... ] >>>> @@ -1100,6 +1109,7 @@ static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p, >>>> mm->pmd_huge_pte = NULL; >>>> #endif >>>> mm_init_uprobes_state(mm); >>>> + mm_init_sframe(mm); >>>> hugetlb_count_init(mm); >>>> >>>> mm_flags_clear_all(mm); >>> >>> When a process forks, this initializes an empty sframe_mt for the child's >>> mm_struct. While dup_mmap() duplicates the parent's VMAs, it doesn't appear >>> that the registered .sframe entries are propagated to the child's maple tree. >>> Will child processes silently lose their .sframe unwind data for shared >>> libraries registered prior to the fork? >> >> Does this ring any bell, Steven? I ran into it with my signal frame >> stacktracing test on s390. I think we discussed this during one of the >> SFrame calls and it got lost. > > Oh, this is a good point. I think we need to copy the sframe mt on > fork, not initialize it. I'll send a patch with my next version very soon. Hopefully you did not spend too much time on that yet. Review will be much appreciated! Regards, Jens -- Jens Remus Linux on Z Development (D3303) jremus@de.ibm.com / jremus@linux.ibm.com IBM Deutschland Research & Development GmbH; Vorsitzender des Aufsichtsrats: Wolfgang Wendt; Geschäftsführung: David Faller; Sitz der Gesellschaft: Ehningen; Registergericht: Amtsgericht Stuttgart, HRB 243294 IBM Data Privacy Statement: https://www.ibm.com/privacy/