From: Ong Boon Leong Date: Wed, 31 Mar 2021 13:25:03 +0000 (+0800) Subject: xdp: fix xdp_return_frame() kernel BUG throw for page_pool memory model X-Git-Tag: accepted/tizen/unified/20230118.172025~7507^2~41 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=622d13694b5f048c01caa7ba548498d9880d4cb0;p=platform%2Fkernel%2Flinux-rpi.git xdp: fix xdp_return_frame() kernel BUG throw for page_pool memory model 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 Acked-by: Jesper Dangaard Brouer Signed-off-by: David S. Miller --- diff --git a/net/core/xdp.c b/net/core/xdp.c index 0535497..858276e 100644 --- a/net/core/xdp.c +++ b/net/core/xdp.c @@ -350,7 +350,8 @@ 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;