[PATCH bpf-next] bpf: Do not alloc arena on unsupported arches

[PATCH bpf-next] bpf: Do not alloc arena on unsupported arches

[Viktor Malik]

Do not allocate BPF arena on arches that do not support it, instead
return EOPNOTSUPP. This is useful to prevent bugs such as soft lockups
while trying to free the arena which we have witnessed on ppc64le [1].

[1] https://lore.kernel.org/bpf/4afdcb50-13f2-4772-8db1-3fd02bd985b3@redhat.com/

Signed-off-by: Viktor Malik <vmalik@redhat.com>
---
 kernel/bpf/arena.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/kernel/bpf/arena.c b/kernel/bpf/arena.c
index 3e1dfe349ced..945a5680f6a5 100644
--- a/kernel/bpf/arena.c
+++ b/kernel/bpf/arena.c
@@ -3,6 +3,7 @@
 #include <linux/bpf.h>
 #include <linux/btf.h>
 #include <linux/err.h>
+#include "linux/filter.h"
 #include <linux/btf_ids.h>
 #include <linux/vmalloc.h>
 #include <linux/pagemap.h>
@@ -99,6 +100,9 @@ static struct bpf_map *arena_map_alloc(union bpf_attr *attr)
 	u64 vm_range;
 	int err = -ENOMEM;
 
+	if (!bpf_jit_supports_arena())
+		return ERR_PTR(-EOPNOTSUPP);
+
 	if (attr->key_size || attr->value_size || attr->max_entries == 0 ||
 	    /* BPF_F_MMAPABLE must be set */
 	    !(attr->map_flags & BPF_F_MMAPABLE) ||
-- 
2.47.0

Re: [PATCH bpf-next] bpf: Do not alloc arena on unsupported arches

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to bpf/bpf-next.git (master)
by Alexei Starovoitov <ast@kernel.org>:

On Fri, 15 Nov 2024 09:25:48 +0100 you wrote:
> Do not allocate BPF arena on arches that do not support it, instead
> return EOPNOTSUPP. This is useful to prevent bugs such as soft lockups
> while trying to free the arena which we have witnessed on ppc64le [1].
> 
> [1] https://lore.kernel.org/bpf/4afdcb50-13f2-4772-8db1-3fd02bd985b3@redhat.com/
> 
> Signed-off-by: Viktor Malik <vmalik@redhat.com>
> 
> [...]

Here is the summary with links:
  - [bpf-next] bpf: Do not alloc arena on unsupported arches
    https://git.kernel.org/bpf/bpf-next/c/ab4dc30c5322

You are awesome, thank you!
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