6.13-stable review patch. If anyone has any objections, please let me know.
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From: Pei Xiao xiaopei01@kylinos.cn
[ Upstream commit dfa94ce54f4139c893b9c4ec17df6f7c6a7515d3 ]
Use an API that resembles more the actual use of mmap_count.
Found by cocci: kernel/bpf/arena.c:245:6-25: WARNING: atomic_dec_and_test variation before object free at line 249.
Fixes: b90d77e5fd78 ("bpf: Fix remap of arena.") Reported-by: kernel test robot lkp@intel.com Closes: https://lore.kernel.org/oe-kbuild-all/202412292037.LXlYSHKl-lkp@intel.com/ Signed-off-by: Pei Xiao xiaopei01@kylinos.cn Link: https://lore.kernel.org/r/6ecce439a6bc81adb85d5080908ea8959b792a50.173554281... Signed-off-by: Alexei Starovoitov ast@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/bpf/arena.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/kernel/bpf/arena.c b/kernel/bpf/arena.c index 945a5680f6a54..8caf56a308d96 100644 --- a/kernel/bpf/arena.c +++ b/kernel/bpf/arena.c @@ -218,7 +218,7 @@ static u64 arena_map_mem_usage(const struct bpf_map *map) struct vma_list { struct vm_area_struct *vma; struct list_head head; - atomic_t mmap_count; + refcount_t mmap_count; };
static int remember_vma(struct bpf_arena *arena, struct vm_area_struct *vma) @@ -228,7 +228,7 @@ static int remember_vma(struct bpf_arena *arena, struct vm_area_struct *vma) vml = kmalloc(sizeof(*vml), GFP_KERNEL); if (!vml) return -ENOMEM; - atomic_set(&vml->mmap_count, 1); + refcount_set(&vml->mmap_count, 1); vma->vm_private_data = vml; vml->vma = vma; list_add(&vml->head, &arena->vma_list); @@ -239,7 +239,7 @@ static void arena_vm_open(struct vm_area_struct *vma) { struct vma_list *vml = vma->vm_private_data;
- atomic_inc(&vml->mmap_count); + refcount_inc(&vml->mmap_count); }
static void arena_vm_close(struct vm_area_struct *vma) @@ -248,7 +248,7 @@ static void arena_vm_close(struct vm_area_struct *vma) struct bpf_arena *arena = container_of(map, struct bpf_arena, map); struct vma_list *vml = vma->vm_private_data;
- if (!atomic_dec_and_test(&vml->mmap_count)) + if (!refcount_dec_and_test(&vml->mmap_count)) return; guard(mutex)(&arena->lock); /* update link list under lock */