From: "Liam R. Howlett" <Liam.Howlett@xxxxxxxxxx> The maple tree was already tracking VMAs in this function by an earlier commit, but the rbtree iterator was being used to iterate the list. Change the iterator to use a maple tree native iterator and switch to the maple tree advanced API to avoid multiple walks of the tree during insert operations. Unexport the now-unused vma_store() function. For performance reasons we bulk allocate the maple tree nodes. The node calculations are done internally to the tree and use the VMA count and assume the worst-case node requirements. The VM_DONT_COPY flag does not allow for the most efficient copy method of the tree and so a bulk loading algorithm is used. Link: https://lkml.kernel.org/r/20220504010716.661115-16-Liam.Howlett@xxxxxxxxxx Signed-off-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx> Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx> Acked-by: Vlastimil Babka <vbabka@xxxxxxx> Cc: Catalin Marinas <catalin.marinas@xxxxxxx> Cc: David Howells <dhowells@xxxxxxxxxx> Cc: SeongJae Park <sj@xxxxxxxxxx> Cc: Will Deacon <will@xxxxxxxxxx> Cc: Davidlohr Bueso <dave@xxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/mm.h | 2 -- kernel/fork.c | 12 +++++++++--- 2 files changed, 9 insertions(+), 5 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index f22c6f71a18c..27fa36a7c093 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -2612,8 +2612,6 @@ extern bool arch_has_descending_max_zone_pfns(void); /* nommu.c */ extern atomic_long_t mmap_pages_allocated; extern int nommu_shrink_inode_mappings(struct inode *, size_t, size_t); -/* mmap.c */ -void vma_mas_store(struct vm_area_struct *vma, struct ma_state *mas); /* interval_tree.c */ void vma_interval_tree_insert(struct vm_area_struct *node, diff --git a/kernel/fork.c b/kernel/fork.c index 1840da0732f6..4ecca79556eb 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -583,9 +583,10 @@ static __latent_entropy int dup_mmap(struct mm_struct *mm, struct vm_area_struct *mpnt, *tmp, *prev, **pprev; struct rb_node **rb_link, *rb_parent; int retval; - unsigned long charge; - LIST_HEAD(uf); + unsigned long charge = 0; + MA_STATE(old_mas, &oldmm->mm_mt, 0, 0); MA_STATE(mas, &mm->mm_mt, 0, 0); + LIST_HEAD(uf); uprobe_start_dup_mmap(); if (mmap_write_lock_killable(oldmm)) { @@ -620,7 +621,12 @@ static __latent_entropy int dup_mmap(struct mm_struct *mm, goto out; prev = NULL; - for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) { + + retval = mas_expected_entries(&mas, oldmm->map_count); + if (retval) + goto out; + + mas_for_each(&old_mas, mpnt, ULONG_MAX) { struct file *file; if (mpnt->vm_flags & VM_DONTCOPY) { -- 2.35.1
