From: Ong Boon Leong boon.leong.ong@intel.com
[ Upstream commit 622d13694b5f048c01caa7ba548498d9880d4cb0 ]
xdp_return_frame() may be called outside of NAPI context to return xdpf back to page_pool. xdp_return_frame() calls __xdp_return() with napi_direct = false. For page_pool memory model, __xdp_return() calls xdp_return_frame_no_direct() unconditionally and below false negative kernel BUG throw happened under preempt-rt build:
[ 430.450355] BUG: using smp_processor_id() in preemptible [00000000] code: modprobe/3884 [ 430.451678] caller is __xdp_return+0x1ff/0x2e0 [ 430.452111] CPU: 0 PID: 3884 Comm: modprobe Tainted: G U E 5.12.0-rc2+ #45
Changes in v2: - This patch fixes the issue by making xdp_return_frame_no_direct() is only called if napi_direct = true, as recommended for better by Jesper Dangaard Brouer. Thanks!
Fixes: 2539650fadbf ("xdp: Helpers for disabling napi_direct of xdp_return_frame") Signed-off-by: Ong Boon Leong boon.leong.ong@intel.com Acked-by: Jesper Dangaard Brouer brouer@redhat.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- net/core/xdp.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/net/core/xdp.c b/net/core/xdp.c index d900cebc0acd..b8d7fa47d293 100644 --- a/net/core/xdp.c +++ b/net/core/xdp.c @@ -349,7 +349,8 @@ static void __xdp_return(void *data, struct xdp_mem_info *mem, bool napi_direct, /* mem->id is valid, checked in xdp_rxq_info_reg_mem_model() */ xa = rhashtable_lookup(mem_id_ht, &mem->id, mem_id_rht_params); page = virt_to_head_page(data); - napi_direct &= !xdp_return_frame_no_direct(); + if (napi_direct && xdp_return_frame_no_direct()) + napi_direct = false; page_pool_put_full_page(xa->page_pool, page, napi_direct); rcu_read_unlock(); break;