From 25bed2fdbc8f9cec0d1fa1c72ea02e209da300fa Mon Sep 17 00:00:00 2001 From: "Liam R. Howlett" Date: Fri, 20 Jan 2023 11:26:12 -0500 Subject: [PATCH] UPSTREAM: 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. Link: https://lkml.kernel.org/r/20230120162650.984577-12-Liam.Howlett@oracle.com Signed-off-by: Liam R. Howlett Signed-off-by: Andrew Morton (cherry picked from commit 0378c0a0e9e463b9e31b94fbbbc10f94b34225b6) Bug: 274059236 Change-Id: I3539fb3a08043dae1bc8aaa6c7f285711a0b5548 Signed-off-by: Suren Baghdasaryan --- mm/mmap.c | 14 ++++++-------- 1 file changed, 6 insertions(+), 8 deletions(-) diff --git a/mm/mmap.c b/mm/mmap.c index fa5443930535..e03141ce83ce 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -2314,9 +2314,6 @@ do_mas_align_munmap(struct ma_state *mas, struct vm_area_struct *vma, mt_init_flags(&mt_detach, mas->tree->ma_flags & MT_FLAGS_LOCK_MASK); 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. @@ -2407,8 +2404,6 @@ 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. */ { @@ -2416,6 +2411,7 @@ 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) { @@ -2425,10 +2421,13 @@ 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 @@ -2460,7 +2459,6 @@ end_split_failed: __mt_destroy(&mt_detach); start_split_failed: map_count_exceeded: - mas_destroy(mas); return error; }