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xdp: fix xdp_return_frame() kernel BUG throw for page_pool memory model 

[ Upstream commit 622d13694b ]

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: 2539650fad ("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>
pull/305/head^2
Ong Boon Leong 2021-03-31 21:25:03 +08:00 committed by Greg Kroah-Hartman
parent 4cfae7b238
commit 553290002a
1 changed files with 2 additions and 1 deletions
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3
net/core/xdp.c
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@ -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;