linux_dsm_epyc7002

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Eric Dumazet 72d05c00d7 tcp: select sane initial rcvq_space.space for big MSS Before commit `a337531b94` ("tcp: up initial rmem to 128KB and SYN rwin to around 64KB") small tcp_rmem[1] values were overridden by tcp_fixup_rcvbuf() to accommodate various MSS. This is no longer the case, and Hazem Mohamed Abuelfotoh reported that DRS would not work for MTU 9000 endpoints receiving regular (1500 bytes) frames. Root cause is that tcp_init_buffer_space() uses tp->rcv_wnd for upper limit of rcvq_space.space computation, while it can select later a smaller value for tp->rcv_ssthresh and tp->window_clamp. ss -temoi on receiver would show : skmem:(r0,rb131072,t0,tb46080,f0,w0,o0,bl0,d0) rcv_space:62496 rcv_ssthresh:56596 This means that TCP can not increase its window in tcp_grow_window(), and that DRS can never kick. Fix this by making sure that rcvq_space.space is not bigger than number of bytes that can be held in TCP receive queue. People unable/unwilling to change their kernel can work around this issue by selecting a bigger tcp_rmem[1] value as in : echo "4096 196608 6291456" >/proc/sys/net/ipv4/tcp_rmem Based on an initial report and patch from Hazem Mohamed Abuelfotoh https://lore.kernel.org/netdev/20201204180622.14285-1-abuehaze@amazon.com/ Fixes: `a337531b94` ("tcp: up initial rmem to 128KB and SYN rwin to around 64KB") Fixes: `041a14d267` ("tcp: start receiver buffer autotuning sooner") Reported-by: Hazem Mohamed Abuelfotoh <abuehaze@amazon.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Acked-by: Soheil Hassas Yeganeh <soheil@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>		2020-12-08 16:27:48 -08:00
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drivers	net: ll_temac: Fix potential NULL dereference in temac_probe()	2020-12-08 16:15:46 -08:00
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include	net: stmmac: overwrite the dma_cap.addr64 according to HW design	2020-12-08 14:52:29 -08:00
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net	tcp: select sane initial rcvq_space.space for big MSS	2020-12-08 16:27:48 -08:00
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