The patch titled Subject: ipc/shm: use VMA iterator instead of linked list has been added to the -mm mm-unstable branch. Its filename is ipc-shm-use-vma-iterator-instead-of-linked-list.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/ipc-shm-use-vma-iterator-instead-of-linked-list.patch This patch will later appear in the mm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: "Liam R. Howlett" <Liam.Howlett@xxxxxxxxxx> Subject: ipc/shm: use VMA iterator instead of linked list Date: Mon, 22 Aug 2022 15:06:26 +0000 The VMA iterator is faster than the linked llist, and it can be walked even when VMAs are being removed from the address space, so there's no need to keep track of 'next'. Link: https://lkml.kernel.org/r/20220822150128.1562046-46-Liam.Howlett@xxxxxxxxxx Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx> Signed-off-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx> Cc: Catalin Marinas <catalin.marinas@xxxxxxx> Cc: David Hildenbrand <david@xxxxxxxxxx> Cc: David Howells <dhowells@xxxxxxxxxx> Cc: SeongJae Park <sj@xxxxxxxxxx> Cc: Sven Schnelle <svens@xxxxxxxxxxxxx> Cc: Vlastimil Babka <vbabka@xxxxxxx> Cc: Will Deacon <will@xxxxxxxxxx> Cc: Yu Zhao <yuzhao@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- ipc/shm.c | 21 ++++++++++----------- 1 file changed, 10 insertions(+), 11 deletions(-) --- a/ipc/shm.c~ipc-shm-use-vma-iterator-instead-of-linked-list +++ a/ipc/shm.c @@ -1721,7 +1721,7 @@ long ksys_shmdt(char __user *shmaddr) #ifdef CONFIG_MMU loff_t size = 0; struct file *file; - struct vm_area_struct *next; + VMA_ITERATOR(vmi, mm, addr); #endif if (addr & ~PAGE_MASK) @@ -1751,12 +1751,9 @@ long ksys_shmdt(char __user *shmaddr) * match the usual checks anyway. So assume all vma's are * above the starting address given. */ - vma = find_vma(mm, addr); #ifdef CONFIG_MMU - while (vma) { - next = vma->vm_next; - + for_each_vma(vmi, vma) { /* * Check if the starting address would match, i.e. it's * a fragment created by mprotect() and/or munmap(), or it @@ -1774,6 +1771,7 @@ long ksys_shmdt(char __user *shmaddr) file = vma->vm_file; size = i_size_read(file_inode(vma->vm_file)); do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start, NULL); + mas_pause(&vmi.mas); /* * We discovered the size of the shm segment, so * break out of here and fall through to the next @@ -1781,10 +1779,9 @@ long ksys_shmdt(char __user *shmaddr) * searching for matching vma's. */ retval = 0; - vma = next; + vma = vma_next(&vmi); break; } - vma = next; } /* @@ -1794,17 +1791,19 @@ long ksys_shmdt(char __user *shmaddr) */ size = PAGE_ALIGN(size); while (vma && (loff_t)(vma->vm_end - addr) <= size) { - next = vma->vm_next; - /* finding a matching vma now does not alter retval */ if ((vma->vm_ops == &shm_vm_ops) && ((vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) && - (vma->vm_file == file)) + (vma->vm_file == file)) { do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start, NULL); - vma = next; + mas_pause(&vmi.mas); + } + + vma = vma_next(&vmi); } #else /* CONFIG_MMU */ + vma = vma_lookup(mm, addr); /* under NOMMU conditions, the exact address to be destroyed must be * given */ _ Patches currently in -mm which might be from Liam.Howlett@xxxxxxxxxx are maple-tree-add-new-data-structure.patch radix-tree-test-suite-add-pr_err-define.patch radix-tree-test-suite-add-kmem_cache_set_non_kernel.patch radix-tree-test-suite-add-allocation-counts-and-size-to-kmem_cache.patch radix-tree-test-suite-add-support-for-slab-bulk-apis.patch radix-tree-test-suite-add-lockdep_is_held-to-header.patch lib-test_maple_tree-add-testing-for-maple-tree.patch mm-start-tracking-vmas-with-maple-tree.patch mm-mmap-use-the-maple-tree-in-find_vma-instead-of-the-rbtree.patch mm-mmap-use-the-maple-tree-for-find_vma_prev-instead-of-the-rbtree.patch mm-mmap-use-maple-tree-for-unmapped_area_topdown.patch kernel-fork-use-maple-tree-for-dup_mmap-during-forking.patch damon-convert-__damon_va_three_regions-to-use-the-vma-iterator.patch mm-remove-rb-tree.patch mmap-change-zeroing-of-maple-tree-in-__vma_adjust.patch xen-use-vma_lookup-in-privcmd_ioctl_mmap.patch mm-optimize-find_exact_vma-to-use-vma_lookup.patch mm-khugepaged-optimize-collapse_pte_mapped_thp-by-using-vma_lookup.patch mm-mmap-change-do_brk_flags-to-expand-existing-vma-and-add-do_brk_munmap.patch mm-use-maple-tree-operations-for-find_vma_intersection.patch mm-mmap-use-advanced-maple-tree-api-for-mmap_region.patch mm-remove-vmacache.patch mm-convert-vma_lookup-to-use-mtree_load.patch mm-mmap-move-mmap_region-below-do_munmap.patch mm-mmap-reorganize-munmap-to-use-maple-states.patch mm-mmap-change-do_brk_munmap-to-use-do_mas_align_munmap.patch arm64-change-elfcore-for_each_mte_vma-to-use-vma-iterator.patch fs-proc-base-use-maple-tree-iterators-in-place-of-linked-list.patch userfaultfd-use-maple-tree-iterator-to-iterate-vmas.patch ipc-shm-use-vma-iterator-instead-of-linked-list.patch bpf-remove-vma-linked-list.patch mm-gup-use-maple-tree-navigation-instead-of-linked-list.patch mm-madvise-use-vma_find-instead-of-vma-linked-list.patch mm-memcontrol-stop-using-mm-highest_vm_end.patch mm-mempolicy-use-vma-iterator-maple-state-instead-of-vma-linked-list.patch mm-mprotect-use-maple-tree-navigation-instead-of-vma-linked-list.patch mm-mremap-use-vma_find_intersection-instead-of-vma-linked-list.patch mm-msync-use-vma_find-instead-of-vma-linked-list.patch mm-oom_kill-use-maple-tree-iterators-instead-of-vma-linked-list.patch mm-swapfile-use-vma-iterator-instead-of-vma-linked-list.patch riscv-use-vma-iterator-for-vdso.patch mm-remove-the-vma-linked-list.patch mm-mmap-drop-range_has_overlap-function.patch mm-mmapc-pass-in-mapping-to-__vma_link_file.patch