5.4-stable review patch. If anyone has any objections, please let me know.
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From: Zijian Zhang zijianzhang@bytedance.com
[ Upstream commit af2b7e5b741aaae9ffbba2c660def434e07aa241 ]
In selftests/net/msg_zerocopy.c, it has a while loop keeps calling sendmsg on a socket with MSG_ZEROCOPY flag, and it will recv the notifications until the socket is not writable. Typically, it will start the receiving process after around 30+ sendmsgs. However, as the introduction of commit dfa2f0483360 ("tcp: get rid of sysctl_tcp_adv_win_scale"), the sender is always writable and does not get any chance to run recv notifications. The selftest always exits with OUT_OF_MEMORY because the memory used by opt_skb exceeds the net.core.optmem_max. Meanwhile, it could be set to a different value to trigger OOM on older kernels too.
Thus, we introduce "cfg_notification_limit" to force sender to receive notifications after some number of sendmsgs.
Fixes: 07b65c5b31ce ("test: add msg_zerocopy test") Signed-off-by: Zijian Zhang zijianzhang@bytedance.com Signed-off-by: Xiaochun Lu xiaochun.lu@bytedance.com Reviewed-by: Willem de Bruijn willemb@google.com Link: https://patch.msgid.link/20240701225349.3395580-2-zijianzhang@bytedance.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- tools/testing/selftests/net/msg_zerocopy.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-)
diff --git a/tools/testing/selftests/net/msg_zerocopy.c b/tools/testing/selftests/net/msg_zerocopy.c index bdc03a2097e85..926556febc83c 100644 --- a/tools/testing/selftests/net/msg_zerocopy.c +++ b/tools/testing/selftests/net/msg_zerocopy.c @@ -85,6 +85,7 @@ static bool cfg_rx; static int cfg_runtime_ms = 4200; static int cfg_verbose; static int cfg_waittime_ms = 500; +static int cfg_notification_limit = 32; static bool cfg_zerocopy;
static socklen_t cfg_alen; @@ -95,6 +96,7 @@ static char payload[IP_MAXPACKET]; static long packets, bytes, completions, expected_completions; static int zerocopied = -1; static uint32_t next_completion; +static uint32_t sends_since_notify;
static unsigned long gettimeofday_ms(void) { @@ -208,6 +210,7 @@ static bool do_sendmsg(int fd, struct msghdr *msg, bool do_zerocopy, int domain) error(1, errno, "send"); if (cfg_verbose && ret != len) fprintf(stderr, "send: ret=%u != %u\n", ret, len); + sends_since_notify++;
if (len) { packets++; @@ -460,6 +463,7 @@ static bool do_recv_completion(int fd, int domain) static void do_recv_completions(int fd, int domain) { while (do_recv_completion(fd, domain)) {} + sends_since_notify = 0; }
/* Wait for all remaining completions on the errqueue */ @@ -549,6 +553,9 @@ static void do_tx(int domain, int type, int protocol) else do_sendmsg(fd, &msg, cfg_zerocopy, domain);
+ if (cfg_zerocopy && sends_since_notify >= cfg_notification_limit) + do_recv_completions(fd, domain); + while (!do_poll(fd, POLLOUT)) { if (cfg_zerocopy) do_recv_completions(fd, domain); @@ -708,7 +715,7 @@ static void parse_opts(int argc, char **argv)
cfg_payload_len = max_payload_len;
- while ((c = getopt(argc, argv, "46c:C:D:i:mp:rs:S:t:vz")) != -1) { + while ((c = getopt(argc, argv, "46c:C:D:i:l:mp:rs:S:t:vz")) != -1) { switch (c) { case '4': if (cfg_family != PF_UNSPEC) @@ -736,6 +743,9 @@ static void parse_opts(int argc, char **argv) if (cfg_ifindex == 0) error(1, errno, "invalid iface: %s", optarg); break; + case 'l': + cfg_notification_limit = strtoul(optarg, NULL, 0); + break; case 'm': cfg_cork_mixed = true; break;