On Tue, Feb 15, 2022 at 02:37:44PM +0000, Liam Howlett wrote: > The maple tree is an RCU-safe range based B-tree designed to use modern > processor cache efficiently. There are a number of places in the kernel > that a non-overlapping range-based tree would be beneficial, especially > one with a simple interface. The first user that is covered in this > patch set is the vm_area_struct, where three data structures are > replaced by the maple tree: the augmented rbtree, the vma cache, and the > linked list of VMAs in the mm_struct. The long term goal is to reduce > or remove the mmap_sem contention. > > The tree has a branching factor of 10 for non-leaf nodes and 16 for leaf > nodes. With the increased branching factor, it is significantly shorter than > the rbtree so it has fewer cache misses. The removal of the linked list > between subsequent entries also reduces the cache misses and the need to pull > in the previous and next VMA during many tree alterations. > > This patch is based on v5.17-rc4 > > git: https://github.com/oracle/linux-uek/tree/howlett/maple/20220214 Just a heads-up. I noticed an use-after-free in today's linux-next below. I am running out of time to fully triage this, but I noticed this is the only series (not sure which revision) heavily touched mm/mmap.c recently there. BUG: KASAN: use-after-free in move_vma.isra.0 Read of size 8 at addr ffff0009ce752ac8 by task systemd-logind/1280 CPU: 21 PID: 1280 Comm: systemd-logind Not tainted 5.17.0-rc5-next-20220223-dirty #242 Hardware name: MiTAC RAPTOR EV-883832-X3-0001/RAPTOR, BIOS 1.6 06/28/2020 Call trace: dump_backtrace show_stack dump_stack_lvl print_address_description.constprop.0 kasan_report __asan_report_load8_noabort move_vma.isra.0 move_vma at /usr/src/linux-next/mm/mremap.c:714 __do_sys_mremap __arm64_sys_mremap invoke_syscall el0_svc_common.constprop.0 do_el0_svc el0_svc el0t_64_sync_handler el0t_64_sync Allocated by task 1280: kasan_save_stack __kasan_slab_alloc slab_post_alloc_hook kmem_cache_alloc vm_area_alloc vm_area_alloc at /usr/src/linux-next/kernel/fork.c:455 mmap_region mmap_region at /usr/src/linux-next/mm/mmap.c:2585 do_mmap vm_mmap_pgoff ksys_mmap_pgoff __arm64_sys_mmap invoke_syscall el0_svc_common.constprop.0 do_el0_svc el0_svc el0t_64_sync_handler el0t_64_sync Freed by task 1280: kasan_save_stack kasan_set_track kasan_set_free_info __kasan_slab_free kmem_cache_free vm_area_free remove_vma remove_vma at /usr/src/linux-next/mm/mmap.c:187 do_mas_align_munmap.isra.0 remove_mt at /usr/src/linux-next/mm/mmap.c:2176 (inlined by) do_mas_align_munmap at /usr/src/linux-next/mm/mmap.c:2437 do_mas_munmap do_mas_munmap at /usr/src/linux-next/mm/mmap.c:2483 do_munmap move_vma.isra.0 __do_sys_mremap __arm64_sys_mremap invoke_syscall el0_svc_common.constprop.0 do_el0_svc el0_svc el0t_64_sync_handler el0t_64_sync The buggy address belongs to the object at ffff0009ce752aa8 which belongs to the cache vm_area_struct of size 144 The buggy address is located 32 bytes inside of 144-byte region [ffff0009ce752aa8, ffff0009ce752b38) The buggy address belongs to the page: page:fffffc002739d400 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0xa4e750 head:fffffc002739d400 order:2 compound_mapcount:0 compound_pincount:0 memcg:ffff0009ce456e01 flags: 0xbfffc0000010200(slab|head|node=0|zone=2|lastcpupid=0xffff) raw: 0bfffc0000010200 fffffc002739f108 fffffc00273a3b08 ffff000800f53380 raw: 0000000000000000 0000000000210021 00000001ffffffff ffff0009ce456e01 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff0009ce752980: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff0009ce752a00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff0009ce752a80: fc fc fc fc fc fa fb fb fb fb fb fb fb fb fb fb ^ ffff0009ce752b00: fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc fc ffff0009ce752b80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
