[PATCH bpf-next v2 2/2] bpf: Migrate dynptr file to kmalloc_nolock

[Mykyta Yatsenko <mykyta.yatsenko5@gmail.com>]

From: Mykyta Yatsenko <yatsenko@meta.com>

Replace bpf_mem_alloc/bpf_mem_free with kmalloc_nolock/kfree_nolock for
bpf_dynptr_file_impl, continuing the migration away from bpf_mem_alloc
now that kmalloc can be used from NMI context.

freader_cleanup() runs before kfree_nolock() while the dynptr still
holds exclusive access, so plain kfree_nolock() is safe — no concurrent
readers can access the object.

Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
---
 kernel/bpf/helpers.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index 4c3011ef631f..7bb8b1339e2f 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -4435,7 +4435,7 @@ static int make_file_dynptr(struct file *file, u32 flags, bool may_sleep,
 		return -EINVAL;
 	}
 
-	state = bpf_mem_alloc(&bpf_global_ma, sizeof(struct bpf_dynptr_file_impl));
+	state = kmalloc_nolock(sizeof(*state), 0, NUMA_NO_NODE);
 	if (!state) {
 		bpf_dynptr_set_null(ptr);
 		return -ENOMEM;
@@ -4467,7 +4467,7 @@ __bpf_kfunc int bpf_dynptr_file_discard(struct bpf_dynptr *dynptr)
 		return 0;
 
 	freader_cleanup(&df->freader);
-	bpf_mem_free(&bpf_global_ma, df);
+	kfree_nolock(df);
 	bpf_dynptr_set_null(ptr);
 	return 0;
 }

-- 
2.52.0