From 723e1e8b7756a552f4d6ddc8047bffe452187617 Mon Sep 17 00:00:00 2001 From: "Liam R. Howlett" Date: Fri, 30 Aug 2024 00:01:01 -0400 Subject: [PATCH] mm/vma.h: optimise vma_munmap_struct The vma_munmap_struct has a hole of 4 bytes and pushes the struct to three cachelines. Relocating the three booleans upwards allows for the struct to only use two cachelines (as reported by pahole on amd64). Before: struct vma_munmap_struct { struct vma_iterator * vmi; /* 0 8 */ struct vm_area_struct * vma; /* 8 8 */ struct vm_area_struct * prev; /* 16 8 */ struct vm_area_struct * next; /* 24 8 */ struct list_head * uf; /* 32 8 */ long unsigned int start; /* 40 8 */ long unsigned int end; /* 48 8 */ long unsigned int unmap_start; /* 56 8 */ /* --- cacheline 1 boundary (64 bytes) --- */ long unsigned int unmap_end; /* 64 8 */ int vma_count; /* 72 4 */ /* XXX 4 bytes hole, try to pack */ long unsigned int nr_pages; /* 80 8 */ long unsigned int locked_vm; /* 88 8 */ long unsigned int nr_accounted; /* 96 8 */ long unsigned int exec_vm; /* 104 8 */ long unsigned int stack_vm; /* 112 8 */ long unsigned int data_vm; /* 120 8 */ /* --- cacheline 2 boundary (128 bytes) --- */ bool unlock; /* 128 1 */ bool clear_ptes; /* 129 1 */ bool closed_vm_ops; /* 130 1 */ /* size: 136, cachelines: 3, members: 19 */ /* sum members: 127, holes: 1, sum holes: 4 */ /* padding: 5 */ /* last cacheline: 8 bytes */ }; After: struct vma_munmap_struct { struct vma_iterator * vmi; /* 0 8 */ struct vm_area_struct * vma; /* 8 8 */ struct vm_area_struct * prev; /* 16 8 */ struct vm_area_struct * next; /* 24 8 */ struct list_head * uf; /* 32 8 */ long unsigned int start; /* 40 8 */ long unsigned int end; /* 48 8 */ long unsigned int unmap_start; /* 56 8 */ /* --- cacheline 1 boundary (64 bytes) --- */ long unsigned int unmap_end; /* 64 8 */ int vma_count; /* 72 4 */ bool unlock; /* 76 1 */ bool clear_ptes; /* 77 1 */ bool closed_vm_ops; /* 78 1 */ /* XXX 1 byte hole, try to pack */ long unsigned int nr_pages; /* 80 8 */ long unsigned int locked_vm; /* 88 8 */ long unsigned int nr_accounted; /* 96 8 */ long unsigned int exec_vm; /* 104 8 */ long unsigned int stack_vm; /* 112 8 */ long unsigned int data_vm; /* 120 8 */ /* size: 128, cachelines: 2, members: 19 */ /* sum members: 127, holes: 1, sum holes: 1 */ }; Link: https://lkml.kernel.org/r/20240830040101.822209-22-Liam.Howlett@oracle.com Signed-off-by: Liam R. Howlett Reviewed-by: Lorenzo Stoakes Cc: Bert Karwatzki Cc: Jeff Xu Cc: Jiri Olsa Cc: Kees Cook Cc: Lorenzo Stoakes Cc: Mark Brown Cc: Matthew Wilcox Cc: "Paul E. McKenney" Cc: Paul Moore Cc: Sidhartha Kumar Cc: Suren Baghdasaryan Cc: Vlastimil Babka Signed-off-by: Andrew Morton --- mm/vma.h | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/mm/vma.h b/mm/vma.h index 45fbc56bc0b0..2a3a5c89a33b 100644 --- a/mm/vma.h +++ b/mm/vma.h @@ -40,15 +40,16 @@ struct vma_munmap_struct { unsigned long unmap_start; /* Unmap PTE start */ unsigned long unmap_end; /* Unmap PTE end */ int vma_count; /* Number of vmas that will be removed */ + bool unlock; /* Unlock after the munmap */ + bool clear_ptes; /* If there are outstanding PTE to be cleared */ + bool closed_vm_ops; /* call_mmap() was encountered, so vmas may be closed */ + /* 1 byte hole */ unsigned long nr_pages; /* Number of pages being removed */ unsigned long locked_vm; /* Number of locked pages */ unsigned long nr_accounted; /* Number of VM_ACCOUNT pages */ unsigned long exec_vm; unsigned long stack_vm; unsigned long data_vm; - bool unlock; /* Unlock after the munmap */ - bool clear_ptes; /* If there are outstanding PTE to be cleared */ - bool closed_vm_ops; /* call_mmap() was encountered, so vmas may be closed */ }; #ifdef CONFIG_DEBUG_VM_MAPLE_TREE