From f244c41fc185d1eba19a40c415a7dfb39a591fcc Mon Sep 17 00:00:00 2001 From: "Liam R. Howlett" Date: Wed, 9 Nov 2022 10:29:14 -0500 Subject: [PATCH] mm/mmap: Remove preallocation from do_mas_align_munmap() In preparation of passing the vma state through split, the pre-allocation that occurs before the split has to be moved to after. Since the preallocation would then live right next to the store, just call store instead of preallocating. This effectively restores the potential error path of splitting and not munmap'ing which pre-dates the maple tree. Signed-off-by: Liam R. Howlett --- mm/mmap.c | 14 ++++++-------- 1 file changed, 6 insertions(+), 8 deletions(-) diff --git a/mm/mmap.c b/mm/mmap.c index 560f66e49749..fe200ac49f46 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -2384,9 +2384,6 @@ do_mas_align_munmap(struct ma_state *mas, struct vm_area_struct *vma, mt_init_flags(&mt_detach, MT_FLAGS_LOCK_EXTERN); mt_set_external_lock(&mt_detach, &mm->mmap_lock); - if (mas_preallocate(mas, vma, GFP_KERNEL)) - return -ENOMEM; - mas->last = end - 1; /* * If we need to split any vma, do it now to save pain later. @@ -2477,8 +2474,6 @@ do_mas_align_munmap(struct ma_state *mas, struct vm_area_struct *vma, goto userfaultfd_error; } - /* Point of no return */ - mas_set_range(mas, start, end - 1); #if defined(CONFIG_DEBUG_VM_MAPLE_TREE) /* Make sure no VMAs are about to be lost. */ { @@ -2486,6 +2481,7 @@ do_mas_align_munmap(struct ma_state *mas, struct vm_area_struct *vma, struct vm_area_struct *vma_mas, *vma_test; int test_count = 0; + mas_set_range(mas, start, end - 1); rcu_read_lock(); vma_test = mas_find(&test, end - 1); mas_for_each(mas, vma_mas, end - 1) { @@ -2495,10 +2491,13 @@ do_mas_align_munmap(struct ma_state *mas, struct vm_area_struct *vma, } rcu_read_unlock(); BUG_ON(count != test_count); - mas_set_range(mas, start, end - 1); } #endif - mas_store_prealloc(mas, NULL); + /* Point of no return */ + mas_set_range(mas, start, end - 1); + if (mas_store_gfp(mas, NULL, GFP_KERNEL)) + return -ENOMEM; + mm->map_count -= count; /* * Do not downgrade mmap_lock if we are next to VM_GROWSDOWN or @@ -2530,7 +2529,6 @@ end_split_failed: __mt_destroy(&mt_detach); start_split_failed: map_count_exceeded: - mas_destroy(mas); return error; } -- 2.49.0