Re: [Crash-utility] [PATCH v5 0/6] Add maple tree vma iteration support for crash

Patchset [1] introduces maple tree data structure for linux, and the modification on mm subsystem. The main impact on crash utility, is the modification on vm_area_struct. Patch [2][3] removed the rbtree and linked list iteration of vm_area_struct, making it impossible for crash to iterate vma in the traditional way. For example, we can observe the failing of crash cmd vm/fuser on kernel which has integrated with patchset [1]. This patchset deals with the issue by porting and adapting kernel's maple tree vma iteration code to crash utility. It has been tested on linux-next-next-20220914 [4]. [1]: https://lore.kernel.org/all/20220906194824.2110408-1-Liam.Howlett@oracle.... [2]: https://github.com/oracle/linux-uek/commit/d19703645b80abe35dff1a88449d07... [3]: https://github.com/oracle/linux-uek/commit/91dee01f1ebb6b6587463b6ee6f7bb... [4]: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/snaps... v1 -> v2: 1) Move xarray.h and maple_tree_vma.h into maple.h. 2) Remove variable-length array for maple_tree.c. 3) Add tree cmd and do_maple_tree() support for maple tree. 4) Other small modifications. v2 -> v3: 1) Remove for_each_vma() macro, and all its dependence functions such as mas_find(), and use mt_dump()(aka do_maple_tree_traverse()) as a way for maple tree iteration instead. 2) Make do_maple_tree_info and maple_tree_ops local variable instead of global variable. 3) Show only valid maple entries by tree cmd. 4) Remove empty structures, such as maple_tree{}/maple_metadata{}, use void * instead. 5) Other changes based on Kazu and Lianbo's comments. v3 -> v4: 1) Rename maple_tree/node_struct to maple_tree/node. 2) Use ULONG(ptr) to replace *(unsigned long *)ptr. 3) Replace void * with ulong. 4) Add maple tree examples to help_tree EXAMPLES section. 5) Remove unused maple_tree_mt variable to simplify do_mt_entry(), do_mt_node() and do_mt_range64() functions. 6) Removed unused radix variable of maple_tree_ops. 7) Rebase the code to the latest in upstream. v4 -> v5: 1) Several formatting/wrapping/renaming issues suggested by Kazu. 2) Replace cases as *((void **)(buf + OFFSET(xx)) + i) to VOID_PTR(buf + OFFSET(xx) + sizeof(void *) * i)