From: Kazuhito Hagio <k-hagio-ab(a)nec.com&gt; Kernel commit b8fea7af0e40 ("sched/fair: Allocate cfs_tg_state with percpu allocator") changed task_group.cfs_rq from a pointer array to a per-cpu variable allocated by the per-cpu allocator. Without the patch, the "runq -g" option fails with the following error on the first time, and with a segmentation fault on the second time. crash> runq -g CPU 0 CURRENT: PID: 5687 TASK: ffff8b0bc175a2c0 COMMAND: "bash" ROOT_TASK_GROUP: ffffffff93a55600 CFS_RQ: 0 runq: invalid kernel virtual address: 58 type: "curr" crash> runq -g Segmentation fault (core dumped) Since there is no way to determine whether it is a per-cpu variable, check wthether it is a pointer array or not. Signed-off-by: Kazuhito Hagio <k-hagio-ab(a)nec.com&gt; --- Hi, I could not find a way to determine it's a __percpu variable or not, any better ideas?

defs.h | 2 ++ kernel.c | 14 ++++++++++++++ symbols.c | 27 +++++++++++++++++++++++++++ task.c | 30 ++++++++++++++++++++++-------- 4 files changed, 65 insertions(+), 8 deletions(-) diff --git a/defs.h b/defs.h index a4f70b773cd7..caa4faabb73e 100644 --- a/defs.h +++ b/defs.h @@ -691,6 +691,7 @@ struct new_utsname { #define KMOD_PAX (0x100ULL) #define KMOD_MEMORY (0x200ULL) #define IRQ_DESC_TREE_MAPLE (0x400ULL) +#define PER_CPU_CFS_RQ (0x800ULL) #define XEN() (kt->flags & ARCH_XEN) #define OPENVZ() (kt->flags & ARCH_OPENVZ) @@ -5884,6 +5885,7 @@ void parse_for_member_extended(struct datatype_member *, ulong); void add_to_downsized(char *); int is_downsized(char *); int is_string(char *, char *); +int is_ptrptr(char *, char *); struct syment *symbol_complete_match(const char *, struct syment *); /* diff --git a/kernel.c b/kernel.c index eb9754c5e082..e53038d5d8db 100644 --- a/kernel.c +++ b/kernel.c @@ -400,6 +400,18 @@ kernel_init() MEMBER_OFFSET_INIT(task_group_rt_rq, "task_group", "rt_rq"); MEMBER_OFFSET_INIT(task_group_parent, "task_group", "parent"); + /* + * task_group.cfs_rq was changed from a pointer array to a per-cpu + * variable at Linux 7.2 (b8fea7af0e40). Since there is no way to + * determine it, we check whether it is a pointer array or not. + * - struct cfs_rq **cfs_rq; + * + struct cfs_rq __percpu *cfs_rq; + */ + if (VALID_MEMBER(task_group_cfs_rq)) { + if (!is_ptrptr("task_group", "cfs_rq")) + kt->flags2 |= PER_CPU_CFS_RQ; + } + /* * In 2.4, smp_send_stop() sets smp_num_cpus back to 1 * in some, but not all, architectures. So if a count @@ -6362,6 +6374,8 @@ dump_kernel_table(int verbose) fprintf(fp, "%sKMOD_PAX", others++ ? "|" : ""); if (kt->flags2 & KMOD_MEMORY) fprintf(fp, "%sKMOD_MEMORY", others++ ? "|" : ""); + if (kt->flags2 & PER_CPU_CFS_RQ) + fprintf(fp, "%sPER_CPU_CFS_RQ", others++ ? "|" : ""); fprintf(fp, ")\n"); fprintf(fp, " stext: %lx\n", kt->stext); diff --git a/symbols.c b/symbols.c index 78e400ba3756..03511c8cbe8c 100644 --- a/symbols.c +++ b/symbols.c @@ -7933,6 +7933,33 @@ is_string(char *structure, char *member) return retval; } +int +is_ptrptr(char *structure, char *member) +{ + int retval; + char *t; + char buf[BUFSIZE]; + + retval = FALSE; + open_tmpfile(); + whatis_datatype(structure, STRUCT_REQUEST, pc->tmpfile); + rewind(pc->tmpfile); + while (fgets(buf, BUFSIZE, pc->tmpfile)) { + if (!(t = strstr(buf, "**"))) + continue; + t += 2; + if (t != strstr(t, member)) + continue; + t += strlen(member); + if (*t == ';') { + retval = TRUE; + break; + } + } + close_tmpfile(); + + return retval; +} /* * Generic function for dumping data structure declarations, with a small diff --git a/task.c b/task.c index d7f3c129a709..5920d6499687 100644 --- a/task.c +++ b/task.c @@ -9464,8 +9464,12 @@ print_parent_task_group_fair(void *t, int cpu) readmem(tgi->task_group + OFFSET(task_group_cfs_rq), KVADDR, &cfs_rq_c, sizeof(ulong), "task_group cfs_rq", FAULT_ON_ERROR); - readmem(cfs_rq_c + cpu * sizeof(ulong), KVADDR, &cfs_rq_p, - sizeof(ulong), "task_group cfs_rq", FAULT_ON_ERROR); + + if (kt->flags2 & PER_CPU_CFS_RQ) + cfs_rq_p = cfs_rq_c + kt->__per_cpu_offset[cpu]; + else + readmem(cfs_rq_c + cpu * sizeof(ulong), KVADDR, &cfs_rq_p, + sizeof(ulong), "task_group cfs_rq", FAULT_ON_ERROR); print_group_header_fair(tgi->depth, cfs_rq_p, tgi); tgi->use = 0; @@ -9491,8 +9495,13 @@ dump_tasks_in_lower_dequeued_cfs_rq(int depth, ulong cfs_rq, int cpu, readmem(tgi_array[i]->task_group + OFFSET(task_group_cfs_rq), KVADDR, &cfs_rq_c, sizeof(ulong), "task_group cfs_rq", FAULT_ON_ERROR); - readmem(cfs_rq_c + cpu * sizeof(ulong), KVADDR, &cfs_rq_p, - sizeof(ulong), "task_group cfs_rq", FAULT_ON_ERROR); + + if (kt->flags2 & PER_CPU_CFS_RQ) + cfs_rq_p = cfs_rq_c + kt->__per_cpu_offset[cpu]; + else + readmem(cfs_rq_c + cpu * sizeof(ulong), KVADDR, &cfs_rq_p, + sizeof(ulong), "task_group cfs_rq", FAULT_ON_ERROR); + if (cfs_rq == cfs_rq_p) continue; @@ -10355,10 +10364,15 @@ dump_tasks_by_task_group(void) readmem(rt_rq + cpu * sizeof(ulong), KVADDR, &rt_rq_p, sizeof(ulong), "task_group rt_rq", FAULT_ON_ERROR); - if (cfs_rq) - readmem(cfs_rq + cpu * sizeof(ulong), KVADDR, - &cfs_rq_p, sizeof(ulong), "task_group cfs_rq", - FAULT_ON_ERROR); + if (cfs_rq) { + if (kt->flags2 & PER_CPU_CFS_RQ) + cfs_rq_p = cfs_rq + kt->__per_cpu_offset[cpu]; + else + readmem(cfs_rq + cpu * sizeof(ulong), KVADDR, + &cfs_rq_p, sizeof(ulong), + "task_group cfs_rq", FAULT_ON_ERROR); + } + fprintf(fp, "%sCPU %d", displayed++ ? "\n" : "", cpu); if (hide_offline_cpu(cpu)) { -- 2.31.1 -- Crash-utility mailing list -- devel(a)lists.crash-utility.osci.io To unsubscribe send an email to devel-leave(a)lists.crash-utility.osci.io https://${domain_name}/admin/lists/devel.lists.crash-utility.osci.io/ Contribution Guidelines: https://github.com/crash-utility/crash/wiki