Re: [Crash-utility] Adding a new command rbtree

----- Original Message ----- > > > ----- Original Message ----- > As it turns out, the radix tree problem I reported seems to be an issue > associated with the kernel version. > But when I try the same thing on a RHEL5 kernel, it always fails like > this: > > crash> tree -t radix -r address_space.page_tree ffff81012eab2e00 > radix_tree_node at ffff81011f9932e8 > struct radix_tree_node { > count = 0x6, > slots = {0xffff810103c06490, 0xffff810103c1c760, > 0xffff810103c58580, 0xffff810103bfb750, 0xffff810103e84cd8, > 0xffff810103bf8b5 > 8, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, > 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, > 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, > 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0 > , 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0}, > tags = {{0x0}, {0x0}} > } > tree: height 1536 is greater than height_to_maxindex[] > index 12 > crash> The reason that the command fails on RHEL5 is due to this part of your patch: 3766 void rdtree_iteration(ulong node_p, struct tree_data *td, char * ppos, ulong indexnum) 3767 { 3768 uint height; 3769 ulong slot; 3770 int index; 3771 int i; 3772 char pos[BUFSIZE]; 3773 3774 if (indexnum != -1) 3775 sprintf(pos, "%s/%ld", ppos, indexnum); 3776 else 3777 sprintf(pos, "%s", ppos); 3778 3779 readmem(node_p + MEMBER_OFFSET("radix_tree_node", "height"), KVADDR, 3780&height, sizeof(uint), "radix_tree_node height", FAULT_ON_ERROR); 3781 3782 if (height> ARRAY_LENGTH(height_to_maxindex)) { 3783 fprintf(fp, "radix_tree_node at %lx\n", node_p); 3784 dump_struct("radix_tree_node", node_p, RADIX(16)); 3785 error(FATAL, "height %d is greater than height_to_maxindex[] \ 3786 index %ld\n", height, ARRAY_LENGTH(height_to_maxindex)); 3787 } In line 3779, you calculate "height" using: MEMBER_OFFSET("radix_tree_node", "height") which returns -1, because RHEL5's radix_tree_node does not have a "height" member: crash> radix_tree_node struct radix_tree_node { unsigned int count; void *slots[64]; long unsigned int tags[2][1]; } SIZE: 536 crash> In RHEL6, a radix_tree_node structure does have a "height" member: crash> radix_tree_node struct radix_tree_node { unsigned int height; unsigned int count; struct rcu_head rcu_head; void *slots[64]; long unsigned int tags[3][1]; } SIZE: 560 crash> In any case, I now see that your patch uses MEMBER_OFFSET(...) in 4 places: $ grep MEMBER_OFFSET 0001-add-a-new-command-tree.patch + readmem(node_p + MEMBER_OFFSET("radix_tree_node", "height"), KVADDR, + readmem(td->start + MEMBER_OFFSET("rb_root", "rb_node"), KVADDR, + readmem(node_p+MEMBER_OFFSET("rb_node", "rb_left"), KVADDR,&left_p, + readmem(node_p+MEMBER_OFFSET("rb_node", "rb_right"), KVADDR,&right_p, $ which is not acceptable, because it hides these kinds of programming errors. For each of the 4 structure members above, add them to the offset_table[] array, initialize them with MEMBER_OFFSET_INIT(), and use OFFSET(...) instead of MEMBER_OFFSET(). Then if your code is incorrect as above, it will fail immediately and show a meaningful error message. Dave -- Crash-utility mailing list Crash-utility(a)redhat.com https://www.redhat.com/mailman/listinfo/crash-utility