Date: Sat, 18 Apr 2026 20:39:44 +0000 From: bugzilla-noreply@freebsd.org To: bugs@FreeBSD.org Subject: [Bug 293871] kern/proc: expose reaper PID and subtree root in struct kinfo_proc Message-ID: <bug-293871-227-iMnlK1alb3@https.bugs.freebsd.org/bugzilla/> In-Reply-To: <bug-293871-227@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=293871 --- Comment #7 from Generic Rikka <rikka.goering@outlook.de> --- The patch has been revised and testing is now complete. The new approach (described in comment 3) has been fully implemented and validated. Rather than introducing a new procctl operation, the patch extends struct kinfo_proc with two new fields: - ki_reaper: PID of the owning reaper process - ki_reapsubtree: PID of the direct child of the reaper that roots the subtree the process belongs to Both fields are pid_t to match their kernel-side counterparts (p_reaper->p_pid and p_reapsubtree in struct proc), and are consistent with the existing procctl_reaper_pidinfo interface. The two remaining KI_NSPARE_INT slots are consumed (KI_NSPARE_INT 2->0), with no change to sizeof(struct kinfo_proc). The following components are updated: - sys/sys/user.h: new fields added from spare slots - sys/kern/kern_proc.c: fill_kinfo_proc_pgrp() populates the new fields; p_reaper is NULL-guarded with NO_PID fallback, consistent with how ki_tpgid is handled; access is safe under proctree_lock held shared by the sysctl machinery - lib/libkvm/kvm_proc.c: kvm_proclist() updated for crash dump consumers, with matching NULL guard - sys/compat/freebsd32/freebsd32.h and freebsd32_kinfo_proc_out(): 32-bit compat struct and conversion updated Runtime validation was performed using a userland test program (attached as kern-proc_reap_status_test.c, with output in kern-proc_reap_status_test.log) covering: - Baseline state before PROC_REAP_ACQUIRE (children show init as reaper) - Post-acquire state (children correctly show the acquiring process as reaper, with per-child subtree roots) - Direct-child subtree tracking - Post-release reparenting back to init All tests pass. The revised patch is attached as kern/proc: expose reaper PID and subtree root in kinfo_proc. With these two fields exposed via kern.proc.all, userland can reconstruct reaper hierarchies without any new kernel interface. The snapshot consistency caveat noted in the earlier review applies equally here, consistent with existing fields such as ki_ppid. -- You are receiving this mail because: You are the assignee for the bug.home | help
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