Re: [Crash-utility] kmem -s issue (gdb can't get offest of struct page lru member)

Hello Dave, When issuing "kmem -s" with crash 6.0.2 (same with 6.0.0) on a s390x linux-3.2 kernel dump, I get the following: ... 1ff0a600 signal_cache 1104 112 150 6 32k 1ff0a540 sighand_cache 2088 82 98 7 32k kmem: invalid structure member offset: page_lru FILE: memory.c LINE: 15856 FUNCTION: count_partial() [./crash] error trace: 80099674 => 80097156 => 80083c40 => 801206ba 801206ba: OFFSET_verify+138 80083c40: get_kmem_cache_slub_data+1028 80097156: dump_kmem_cache_slub+902 80099674: cmd_kmem+6636 kmem: invalid structure member offset: page_lru FILE: memory.c LINE: 15856 FUNCTION: count_partial() I think the reason is that MEMBER_OFFSET_INIT(page_lru, "page", "lru") fails. See the following gdb session: Breakpoint 1, vm_init () at memory.c:375 375 MEMBER_OFFSET_INIT(page_lru, "page", "lru"); (gdb) s datatype_info (name=0x80415c4a "page", member=0x803ce36c "lru", dm=0x0) at symbols.c:4919 4919 if (dm == ANON_MEMBER_OFFSET_REQUEST) (gdb) n 4922 strcpy(buf, name); (gdb) n 4924 req = (struct gnu_request *)GETBUF(sizeof(struct gnu_request)); (gdb) n 4925 req->command = GNU_GET_DATATYPE; (gdb) n 4926 req->flags |= GNU_RETURN_ON_ERROR; (gdb) n 4927 req->name = buf; (gdb) n 4928 req->member = member; (gdb) n 4929 req->fp = pc->nullfp; (gdb) n 4931 gdb_interface(req); (gdb) n 4932 if (req->flags & GNU_COMMAND_FAILED) { (gdb) print *req $1 = {command = 5, buf = 0x0, fp = 0x8060d540, addr = 0, addr2 = 0, count = 0, flags = 8, name = 0x3ffffffda94 "page", length = 56, typecode = 3, typename = 0x0, target_typename = 0x0, target_length = 0, target_typecode = 0, is_typedef = 0, member = 0x803ce36c "lru", member_offset = -1, member_length = 0, member_typecode = 0, value = 0, tagname = 0x0, pc = 0, sp = 0, ra = 0, curframe = 0, frame = 0, prevsp = 0, prevpc = 0, lastsp = 0, task = 0, debug = 0, hookp = 0x0} ---> member_offset = -1 (gdb) n 4937 if (!req->typecode) { (gdb) n 4942 if (!req->typecode) { (gdb) n 4947 member_typecode = TYPE_CODE_UNDEF; (gdb) n 4948 member_size = 0; (gdb) n 4949 type_found = 0; (gdb) n 4951 if (CRASHDEBUG(2)) { (gdb) n 4965 switch (req->typecode) (gdb) n 4968 type_found = STRUCT_REQUEST; (gdb) n 4969 size = req->length; (gdb) n 4970 if (req->member_offset >= 0) { (gdb) n 4975 offset = -1; (gdb) n 4976 member_size = 0; Also crash can't evaluate the offset of the "lru" member: crash> struct page struct page { long unsigned int flags; struct address_space *mapping; struct { union {...}; union {...}; }; union { struct list_head lru; struct {...}; }; union { long unsigned int private; spinlock_t ptl; struct kmem_cache *slab; struct page *first_page; }; } SIZE: 56 crash> struct page.mapping struct page { [8] struct address_space *mapping; } crash> struct page.lru struct: invalid data structure reference: page.lru Any idea why we do not get the offset from gdb? Perhaps a problem with the anonymous union?