On 2022/10/12 17:44, lijiang wrote: > Hi, Tao > Thanks for the work. > On Mon, Sep 19, 2022 at 11:10 PM <crash-utility-request@xxxxxxxxxx> wrote: > >> Date: Mon, 19 Sep 2022 23:10:22 +0800 >> From: Tao Liu <ltao@xxxxxxxxxx> >> To: crash-utility@xxxxxxxxxx >> Subject: [RFC] [PATCH 0/6] Add maple tree vma >> iteration support for crash >> Message-ID: <20220919151028.25830-1-ltao@xxxxxxxxxx> >> Content-Type: text/plain; charset="US-ASCII"; x-default=true >> >> 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]. >> >> > Good job. But I still have several questions about the patchset. > > Can you help try to tidy up the following patches? For example: > Step 1: > - introduce the maple tree data structures and iterative algorithms as > one patch. > - (they include two files: maple_tree.c, maple_tree.h) > > Patch 1: the pure copy-and-paste work, extracting related kernel >> structures, functions, constants to crash. >> Patch 2: minimal code modification for crash adaption, kernel >> structures are kept for member resolving. >> Patch 3: modification on crash memory.c to use the maple vma >> iteration. >> >> The idea is to make patch 1-3 a POC work. >> >> > Step 2: > - imitate the do_rbtree(), do_radix_tree(), do_xarray()..., you could > refer to the filesys.c/tools.c > - the maple tree can be considered as a new structure and algorithm, just > like the rbtree, radix_tree and xarray..., crash can keep the same code > style. > - the advantage is that it is easy to maintain in the future. Agree. The kernel code of the maple tree looks quite complex to make it minimal and crash-like, so I thought that it's ok to copy and convert it. But it may be worth trying. Thanks, Kazu > > Step 3: > - call the do_maple_tree(),... in crash code, etc... > - enable the maple tree support for crash-utility > > That is my concern. But this may increase the difficulty of implementation, > can you also evaluate if it is doable? > > Thanks. > Lianbo > > Patch 4: Get rid of kernel structures by rewriting the structure >> member resolving code into the crash way, aka change >> "node->member" into "readmem(node) and OFFSET(member)" >> Patch 5: print the added variables of offset/size table >> Patch 6: Get rid of the compiling-time assgined arrays. >> >> Patch 4-6 will make the POC work formal for use. >> >> >> [1]: >> https://lore.kernel.org/all/20220906194824.2110408-1-Liam.Howlett@xxxxxxxxxx/ >> [2]: >> https://github.com/oracle/linux-uek/commit/d19703645b80abe35dff1a88449d074b0b5b1bb1 >> [3]: >> https://github.com/oracle/linux-uek/commit/91dee01f1ebb6b6587463b6ee6f7bbc4965f91d5 >> [4]: >> https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/snapshot/linux-next-next-20220914.tar.gz >> >> Tao Liu (6): >> Port linux maple tree related files to crash >> Maple tree kernel code modification for step 1 >> Introduce maple tree vma iteration to memory.c >> Maple tree kernel code modification for step 2 >> Dump maple tree offset variables by help -o >> Remove mt_slots and mt_pivots array assignment >> >> Makefile | 12 +- >> defs.h | 19 ++ >> maple_tree.c | 824 +++++++++++++++++++++++++++++++++++++++++++++++ >> maple_tree.h | 109 +++++++ >> maple_tree_vma.h | 34 ++ >> memory.c | 315 ++++++++++-------- >> symbols.c | 34 ++ >> xarray.h | 70 ++++ >> 8 files changed, 1285 insertions(+), 132 deletions(-) >> create mode 100644 maple_tree.c >> create mode 100644 maple_tree.h >> create mode 100644 maple_tree_vma.h >> create mode 100644 xarray.h >> >> -- >> 2.33.1 -- Crash-utility mailing list Crash-utility@xxxxxxxxxx https://listman.redhat.com/mailman/listinfo/crash-utility Contribution Guidelines: https://github.com/crash-utility/crash/wiki
