JIRA: https://issues.redhat.com/browse/RHEL-83546
commit 1c2709cfff1dedbb9591e989e2f001484208d914
Author: Neal Cardwell <ncardwell@google.com>
Date: Sun Oct 15 13:47:00 2023 -0400
tcp: fix excessive TLP and RACK timeouts from HZ rounding
We discovered from packet traces of slow loss recovery on kernels with
the default HZ=250 setting (and min_rtt < 1ms) that after reordering,
when receiving a SACKed sequence range, the RACK reordering timer was
firing after about 16ms rather than the desired value of roughly
min_rtt/4 + 2ms. The problem is largely due to the RACK reorder timer
calculation adding in TCP_TIMEOUT_MIN, which is 2 jiffies. On kernels
with HZ=250, this is 2*4ms = 8ms. The TLP timer calculation has the
exact same issue.
This commit fixes the TLP transmit timer and RACK reordering timer
floor calculation to more closely match the intended 2ms floor even on
kernels with HZ=250. It does this by adding in a new
TCP_TIMEOUT_MIN_US floor of 2000 us and then converting to jiffies,
instead of the current approach of converting to jiffies and then
adding th TCP_TIMEOUT_MIN value of 2 jiffies.
Our testing has verified that on kernels with HZ=1000, as expected,
this does not produce significant changes in behavior, but on kernels
with the default HZ=250 the latency improvement can be large. For
example, our tests show that for HZ=250 kernels at low RTTs this fix
roughly halves the latency for the RACK reorder timer: instead of
mostly firing at 16ms it mostly fires at 8ms.
Suggested-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Fixes: bb4d991a28 ("tcp: adjust tail loss probe timeout")
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20231015174700.2206872-1-ncardwell.sw@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: CKI Backport Bot <cki-ci-bot+cki-gitlab-backport-bot@redhat.com>
MR: https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-9/-/merge_requests/4765
JIRA: https://issues.redhat.com/browse/RHEL-48648
Various visibility improvements; mainly around drop reasons, reset reason and improved tracepoints this time.
Signed-off-by: Antoine Tenart <atenart@redhat.com>
Approved-by: Chris von Recklinghausen <crecklin@redhat.com>
Approved-by: Marcelo Ricardo Leitner <mleitner@redhat.com>
Approved-by: CKI KWF Bot <cki-ci-bot+kwf-gitlab-com@redhat.com>
Merged-by: Lucas Zampieri <lzampier@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-48648
Upstream Status: linux.git
commit b533fb9cf4f7c6ca2aa255a5a1fdcde49fff2b24
Author: Jason Xing <kernelxing@tencent.com>
Date: Thu Apr 25 11:13:40 2024 +0800
rstreason: make it work in trace world
At last, we should let it work by introducing this reset reason in
trace world.
One of the possible expected outputs is:
... tcp_send_reset: skbaddr=xxx skaddr=xxx src=xxx dest=xxx
state=TCP_ESTABLISHED reason=NOT_SPECIFIED
Signed-off-by: Jason Xing <kernelxing@tencent.com>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Antoine Tenart <atenart@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-48648
Upstream Status: linux.git
Conflicts:\
- Context difference due to missing upstream commit e13ec3da05d1 ("tcp:
annotate lockless access to sk->sk_err") in c9s.
commit 5691276b39daf90294c6a81fb6d62d667f634c92
Author: Jason Xing <kernelxing@tencent.com>
Date: Thu Apr 25 11:13:36 2024 +0800
rstreason: prepare for active reset
Like what we did to passive reset:
only passing possible reset reason in each active reset path.
No functional changes.
Signed-off-by: Jason Xing <kernelxing@tencent.com>
Acked-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Antoine Tenart <atenart@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-41185
Tested: compile only
commit eb44ad4e635132754bfbcb18103f1dcb7058aedd
Author: Eric Dumazet <edumazet@google.com>
Date: Thu Sep 21 20:28:18 2023 +0000
net: annotate data-races around sk->sk_dst_pending_confirm
This field can be read or written without socket lock being held.
Add annotations to avoid load-store tearing.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Xin Long <lxin@redhat.com>
MR: https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-9/-/merge_requests/3921
JIRA: https://issues.redhat.com/browse/RHEL-22708
Upstream Status: linux.git
commit 7267e8dcad6b2f9fce05a6a06335d7040acbc2b6
Author: Salvatore Dipietro <dipiets@amazon.com>
Date: Fri Jan 19 11:01:33 2024 -0800
tcp: Add memory barrier to tcp_push()
On CPUs with weak memory models, reads and updates performed by tcp_push
to the sk variables can get reordered leaving the socket throttled when
it should not. The tasklet running tcp_wfree() may also not observe the
memory updates in time and will skip flushing any packets throttled by
tcp_push(), delaying the sending. This can pathologically cause 40ms
extra latency due to bad interactions with delayed acks.
Adding a memory barrier in tcp_push removes the bug, similarly to the
previous commit bf06200e73 ("tcp: tsq: fix nonagle handling").
smp_mb__after_atomic() is used to not incur in unnecessary overhead
on x86 since not affected.
Patch has been tested using an AWS c7g.2xlarge instance with Ubuntu
22.04 and Apache Tomcat 9.0.83 running the basic servlet below:
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class HelloWorldServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=utf-8");
OutputStreamWriter osw = new OutputStreamWriter(response.getOutputStream(),"UTF-8");
String s = "a".repeat(3096);
osw.write(s,0,s.length());
osw.flush();
}
}
Load was applied using wrk2 (https://github.com/kinvolk/wrk2) from an AWS
c6i.8xlarge instance. Before the patch an additional 40ms latency from P99.99+
values is observed while, with the patch, the extra latency disappears.
No patch and tcp_autocorking=1
./wrk -t32 -c128 -d40s --latency -R10000 http://172.31.60.173:8080/hello/hello
...
50.000% 0.91ms
75.000% 1.13ms
90.000% 1.46ms
99.000% 1.74ms
99.900% 1.89ms
99.990% 41.95ms <<< 40+ ms extra latency
99.999% 48.32ms
100.000% 48.96ms
With patch and tcp_autocorking=1
./wrk -t32 -c128 -d40s --latency -R10000 http://172.31.60.173:8080/hello/hello
...
50.000% 0.90ms
75.000% 1.13ms
90.000% 1.45ms
99.000% 1.72ms
99.900% 1.83ms
99.990% 2.11ms <<< no 40+ ms extra latency
99.999% 2.53ms
100.000% 2.62ms
Patch has been also tested on x86 (m7i.2xlarge instance) which it is not
affected by this issue and the patch doesn't introduce any additional
delay.
Fixes: 7aa5470c2c ("tcp: tsq: move tsq_flags close to sk_wmem_alloc")
Signed-off-by: Salvatore Dipietro <dipiets@amazon.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20240119190133.43698-1-dipiets@amazon.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Antoine Tenart <atenart@redhat.com>
Approved-by: Hangbin Liu <haliu@redhat.com>
Approved-by: Guillaume Nault <gnault@redhat.com>
Approved-by: CKI KWF Bot <cki-ci-bot+kwf-gitlab-com@redhat.com>
Merged-by: Scott Weaver <scweaver@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-22708
Upstream Status: linux.git
commit b548b17a93fd18357a5a6f535c10c1e68719ad32
Author: Eric Dumazet <edumazet@google.com>
Date: Thu Nov 10 19:02:39 2022 +0000
tcp: tcp_wfree() refactoring
Use try_cmpxchg() (instead of cmpxchg()) in a more readable way.
oval = smp_load_acquire(&sk->sk_tsq_flags);
do {
...
} while (!try_cmpxchg(&sk->sk_tsq_flags, &oval, nval));
Reduce indentation level.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20221110190239.3531280-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Antoine Tenart <atenart@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-32164
Tested: LNST, Tier1
Upstream commit:
commit f921a4a5bffa8a0005b190fb9421a7fc1fd716b6
Author: Eric Dumazet <edumazet@google.com>
Date: Tue Oct 17 12:45:26 2023 +0000
tcp: tsq: relax tcp_small_queue_check() when rtx queue contains a single skb
In commit 75eefc6c59 ("tcp: tsq: add a shortcut in tcp_small_queue_check()")
we allowed to send an skb regardless of TSQ limits being hit if rtx queue
was empty or had a single skb, in order to better fill the pipe
when/if TX completions were slow.
Then later, commit 75c119afe1 ("tcp: implement rb-tree based
retransmit queue") accidentally removed the special case for
one skb in rtx queue.
Stefan Wahren reported a regression in single TCP flow throughput
using a 100Mbit fec link, starting from commit 65466904b015 ("tcp: adjust
TSO packet sizes based on min_rtt"). This last commit only made the
regression more visible, because it locked the TCP flow on a particular
behavior where TSQ prevented two skbs being pushed downstream,
adding silences on the wire between each TSO packet.
Many thanks to Stefan for his invaluable help !
Fixes: 75c119afe1 ("tcp: implement rb-tree based retransmit queue")
Link: https://lore.kernel.org/netdev/7f31ddc8-9971-495e-a1f6-819df542e0af@gmx.net/
Reported-by: Stefan Wahren <wahrenst@gmx.net>
Tested-by: Stefan Wahren <wahrenst@gmx.net>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Link: https://lore.kernel.org/r/20231017124526.4060202-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-21432
Tested: LNST, Tier1
Upstream commit:
commit f99cd56230f56c8b6b33713c5be4da5d6766be1f
Author: Dong Chenchen <dongchenchen2@huawei.com>
Date: Sun Dec 10 10:02:00 2023 +0800
net: Remove acked SYN flag from packet in the transmit queue correctly
syzkaller report:
kernel BUG at net/core/skbuff.c:3452!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 6.7.0-rc4-00009-gbee0e7762ad2-dirty #135
RIP: 0010:skb_copy_and_csum_bits (net/core/skbuff.c:3452)
Call Trace:
icmp_glue_bits (net/ipv4/icmp.c:357)
__ip_append_data.isra.0 (net/ipv4/ip_output.c:1165)
ip_append_data (net/ipv4/ip_output.c:1362 net/ipv4/ip_output.c:1341)
icmp_push_reply (net/ipv4/icmp.c:370)
__icmp_send (./include/net/route.h:252 net/ipv4/icmp.c:772)
ip_fragment.constprop.0 (./include/linux/skbuff.h:1234 net/ipv4/ip_output.c:592 net/ipv4/ip_output.c:577)
__ip_finish_output (net/ipv4/ip_output.c:311 net/ipv4/ip_output.c:295)
ip_output (net/ipv4/ip_output.c:427)
__ip_queue_xmit (net/ipv4/ip_output.c:535)
__tcp_transmit_skb (net/ipv4/tcp_output.c:1462)
__tcp_retransmit_skb (net/ipv4/tcp_output.c:3387)
tcp_retransmit_skb (net/ipv4/tcp_output.c:3404)
tcp_retransmit_timer (net/ipv4/tcp_timer.c:604)
tcp_write_timer (./include/linux/spinlock.h:391 net/ipv4/tcp_timer.c:716)
The panic issue was trigered by tcp simultaneous initiation.
The initiation process is as follows:
TCP A TCP B
1. CLOSED CLOSED
2. SYN-SENT --> <SEQ=100><CTL=SYN> ...
3. SYN-RECEIVED <-- <SEQ=300><CTL=SYN> <-- SYN-SENT
4. ... <SEQ=100><CTL=SYN> --> SYN-RECEIVED
5. SYN-RECEIVED --> <SEQ=100><ACK=301><CTL=SYN,ACK> ...
// TCP B: not send challenge ack for ack limit or packet loss
// TCP A: close
tcp_close
tcp_send_fin
if (!tskb && tcp_under_memory_pressure(sk))
tskb = skb_rb_last(&sk->tcp_rtx_queue); //pick SYN_ACK packet
TCP_SKB_CB(tskb)->tcp_flags |= TCPHDR_FIN; // set FIN flag
6. FIN_WAIT_1 --> <SEQ=100><ACK=301><END_SEQ=102><CTL=SYN,FIN,ACK> ...
// TCP B: send challenge ack to SYN_FIN_ACK
7. ... <SEQ=301><ACK=101><CTL=ACK> <-- SYN-RECEIVED //challenge ack
// TCP A: <SND.UNA=101>
8. FIN_WAIT_1 --> <SEQ=101><ACK=301><END_SEQ=102><CTL=SYN,FIN,ACK> ... // retransmit panic
__tcp_retransmit_skb //skb->len=0
tcp_trim_head
len = tp->snd_una - TCP_SKB_CB(skb)->seq // len=101-100
__pskb_trim_head
skb->data_len -= len // skb->len=-1, wrap around
... ...
ip_fragment
icmp_glue_bits //BUG_ON
If we use tcp_trim_head() to remove acked SYN from packet that contains data
or other flags, skb->len will be incorrectly decremented. We can remove SYN
flag that has been acked from rtx_queue earlier than tcp_trim_head(), which
can fix the problem mentioned above.
Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Co-developed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Dong Chenchen <dongchenchen2@huawei.com>
Link: https://lore.kernel.org/r/20231210020200.1539875-1-dongchenchen2@huawei.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
MR: https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-9/-/merge_requests/3301
JIRA: https://issues.redhat.com/browse/RHEL-11592
commit b650d953cd391595e536153ce30b4aab385643ac
Author: mfreemon@cloudflare.com <mfreemon@cloudflare.com>
Date: Sun Jun 11 22:05:24 2023 -0500
tcp: enforce receive buffer memory limits by allowing the tcp window to shrink
Under certain circumstances, the tcp receive buffer memory limit
set by autotuning (sk_rcvbuf) is increased due to incoming data
packets as a result of the window not closing when it should be.
This can result in the receive buffer growing all the way up to
tcp_rmem[2], even for tcp sessions with a low BDP.
To reproduce: Connect a TCP session with the receiver doing
nothing and the sender sending small packets (an infinite loop
of socket send() with 4 bytes of payload with a sleep of 1 ms
in between each send()). This will cause the tcp receive buffer
to grow all the way up to tcp_rmem[2].
As a result, a host can have individual tcp sessions with receive
buffers of size tcp_rmem[2], and the host itself can reach tcp_mem
limits, causing the host to go into tcp memory pressure mode.
The fundamental issue is the relationship between the granularity
of the window scaling factor and the number of byte ACKed back
to the sender. This problem has previously been identified in
RFC 7323, appendix F [1].
The Linux kernel currently adheres to never shrinking the window.
In addition to the overallocation of memory mentioned above, the
current behavior is functionally incorrect, because once tcp_rmem[2]
is reached when no remediations remain (i.e. tcp collapse fails to
free up any more memory and there are no packets to prune from the
out-of-order queue), the receiver will drop in-window packets
resulting in retransmissions and an eventual timeout of the tcp
session. A receive buffer full condition should instead result
in a zero window and an indefinite wait.
In practice, this problem is largely hidden for most flows. It
is not applicable to mice flows. Elephant flows can send data
fast enough to "overrun" the sk_rcvbuf limit (in a single ACK),
triggering a zero window.
But this problem does show up for other types of flows. Examples
are websockets and other type of flows that send small amounts of
data spaced apart slightly in time. In these cases, we directly
encounter the problem described in [1].
RFC 7323, section 2.4 [2], says there are instances when a retracted
window can be offered, and that TCP implementations MUST ensure
that they handle a shrinking window, as specified in RFC 1122,
section 4.2.2.16 [3]. All prior RFCs on the topic of tcp window
management have made clear that sender must accept a shrunk window
from the receiver, including RFC 793 [4] and RFC 1323 [5].
This patch implements the functionality to shrink the tcp window
when necessary to keep the right edge within the memory limit by
autotuning (sk_rcvbuf). This new functionality is enabled with
the new sysctl: net.ipv4.tcp_shrink_window
Additional information can be found at:
https://blog.cloudflare.com/unbounded-memory-usage-by-tcp-for-receive-buffers-and-how-we-fixed-it/
[1] https://www.rfc-editor.org/rfc/rfc7323#appendix-F
[2] https://www.rfc-editor.org/rfc/rfc7323#section-2.4
[3] https://www.rfc-editor.org/rfc/rfc1122#page-91
[4] https://www.rfc-editor.org/rfc/rfc793
[5] https://www.rfc-editor.org/rfc/rfc1323
Signed-off-by: Mike Freemon <mfreemon@cloudflare.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Felix Maurer <fmaurer@redhat.com>
Approved-by: Florian Westphal <fwestpha@redhat.com>
Approved-by: Marcelo Ricardo Leitner <mleitner@redhat.com>
Signed-off-by: Jan Stancek <jstancek@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-11592
Conflicts:
- net/ipv4/sysctl_net_ipv4.c: context difference due to missing new sysctls
- net/ipv4/tcp_ipv4.c: context difference due to missing ccce324dabfe
("tcp: make the first N SYN RTO backoffs linear") and 37ba017dcc3b
("ipv4/tcp: do not use per netns ctl sockets")
commit b650d953cd391595e536153ce30b4aab385643ac
Author: mfreemon@cloudflare.com <mfreemon@cloudflare.com>
Date: Sun Jun 11 22:05:24 2023 -0500
tcp: enforce receive buffer memory limits by allowing the tcp window to shrink
Under certain circumstances, the tcp receive buffer memory limit
set by autotuning (sk_rcvbuf) is increased due to incoming data
packets as a result of the window not closing when it should be.
This can result in the receive buffer growing all the way up to
tcp_rmem[2], even for tcp sessions with a low BDP.
To reproduce: Connect a TCP session with the receiver doing
nothing and the sender sending small packets (an infinite loop
of socket send() with 4 bytes of payload with a sleep of 1 ms
in between each send()). This will cause the tcp receive buffer
to grow all the way up to tcp_rmem[2].
As a result, a host can have individual tcp sessions with receive
buffers of size tcp_rmem[2], and the host itself can reach tcp_mem
limits, causing the host to go into tcp memory pressure mode.
The fundamental issue is the relationship between the granularity
of the window scaling factor and the number of byte ACKed back
to the sender. This problem has previously been identified in
RFC 7323, appendix F [1].
The Linux kernel currently adheres to never shrinking the window.
In addition to the overallocation of memory mentioned above, the
current behavior is functionally incorrect, because once tcp_rmem[2]
is reached when no remediations remain (i.e. tcp collapse fails to
free up any more memory and there are no packets to prune from the
out-of-order queue), the receiver will drop in-window packets
resulting in retransmissions and an eventual timeout of the tcp
session. A receive buffer full condition should instead result
in a zero window and an indefinite wait.
In practice, this problem is largely hidden for most flows. It
is not applicable to mice flows. Elephant flows can send data
fast enough to "overrun" the sk_rcvbuf limit (in a single ACK),
triggering a zero window.
But this problem does show up for other types of flows. Examples
are websockets and other type of flows that send small amounts of
data spaced apart slightly in time. In these cases, we directly
encounter the problem described in [1].
RFC 7323, section 2.4 [2], says there are instances when a retracted
window can be offered, and that TCP implementations MUST ensure
that they handle a shrinking window, as specified in RFC 1122,
section 4.2.2.16 [3]. All prior RFCs on the topic of tcp window
management have made clear that sender must accept a shrunk window
from the receiver, including RFC 793 [4] and RFC 1323 [5].
This patch implements the functionality to shrink the tcp window
when necessary to keep the right edge within the memory limit by
autotuning (sk_rcvbuf). This new functionality is enabled with
the new sysctl: net.ipv4.tcp_shrink_window
Additional information can be found at:
https://blog.cloudflare.com/unbounded-memory-usage-by-tcp-for-receive-buffers-and-how-we-fixed-it/
[1] https://www.rfc-editor.org/rfc/rfc7323#appendix-F
[2] https://www.rfc-editor.org/rfc/rfc7323#section-2.4
[3] https://www.rfc-editor.org/rfc/rfc1122#page-91
[4] https://www.rfc-editor.org/rfc/rfc793
[5] https://www.rfc-editor.org/rfc/rfc1323
Signed-off-by: Mike Freemon <mfreemon@cloudflare.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Felix Maurer <fmaurer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-11592
Conflicts:
- net/ipv4/tcp_input.c: context difference due to missing 240bfd134c59
("tcp: tweak len/truesize ratio for coalesce candidates")
commit 053f368412c9a7bfce2befec8c795113c8cfb0b1
Author: Wei Wang <weiwan@google.com>
Date: Wed Sep 29 10:25:13 2021 -0700
tcp: adjust rcv_ssthresh according to sk_reserved_mem
When user sets SO_RESERVE_MEM socket option, in order to utilize the
reserved memory when in memory pressure state, we adjust rcv_ssthresh
according to the available reserved memory for the socket, instead of
using 4 * advmss always.
Signed-off-by: Wei Wang <weiwan@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Felix Maurer <fmaurer@redhat.com>
JIRA: https://issues.redhat.com/browse/RHEL-14348
Tested: LNST, Tier1
Conflicts: different context, as rhel lacks the upstream commit \
03b123debcbc ("tcp: tcp_enter_quickack_mode() should be static")
Upstream commit:
commit 059217c18be6757b95bfd77ba53fb50b48b8a816
Author: Neal Cardwell <ncardwell@google.com>
Date: Sun Oct 1 11:12:38 2023 -0400
tcp: fix quick-ack counting to count actual ACKs of new data
This commit fixes quick-ack counting so that it only considers that a
quick-ack has been provided if we are sending an ACK that newly
acknowledges data.
The code was erroneously using the number of data segments in outgoing
skbs when deciding how many quick-ack credits to remove. This logic
does not make sense, and could cause poor performance in
request-response workloads, like RPC traffic, where requests or
responses can be multi-segment skbs.
When a TCP connection decides to send N quick-acks, that is to
accelerate the cwnd growth of the congestion control module
controlling the remote endpoint of the TCP connection. That quick-ack
decision is purely about the incoming data and outgoing ACKs. It has
nothing to do with the outgoing data or the size of outgoing data.
And in particular, an ACK only serves the intended purpose of allowing
the remote congestion control to grow the congestion window quickly if
the ACK is ACKing or SACKing new data.
The fix is simple: only count packets as serving the goal of the
quickack mechanism if they are ACKing/SACKing new data. We can tell
whether this is the case by checking inet_csk_ack_scheduled(), since
we schedule an ACK exactly when we are ACKing/SACKing new data.
Fixes: fc6415bcb0 ("[TCP]: Fix quick-ack decrementing with TSO.")
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Reviewed-by: Yuchung Cheng <ycheng@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20231001151239.1866845-1-ncardwell.sw@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2217511
Tested: LNST, Tier1
Upstream commit:
commit bced3f7db95ff2e6ca29dc4d1c9751ab5e736a09
Author: Breno Leitao <leitao@debian.org>
Date: Wed Mar 8 11:07:45 2023 -0800
tcp: tcp_make_synack() can be called from process context
tcp_rtx_synack() now could be called in process context as explained in
0a375c822497 ("tcp: tcp_rtx_synack() can be called from process
context").
tcp_rtx_synack() might call tcp_make_synack(), which will touch per-CPU
variables with preemption enabled. This causes the following BUG:
BUG: using __this_cpu_add() in preemptible [00000000] code: ThriftIO1/5464
caller is tcp_make_synack+0x841/0xac0
Call Trace:
<TASK>
dump_stack_lvl+0x10d/0x1a0
check_preemption_disabled+0x104/0x110
tcp_make_synack+0x841/0xac0
tcp_v6_send_synack+0x5c/0x450
tcp_rtx_synack+0xeb/0x1f0
inet_rtx_syn_ack+0x34/0x60
tcp_check_req+0x3af/0x9e0
tcp_rcv_state_process+0x59b/0x2030
tcp_v6_do_rcv+0x5f5/0x700
release_sock+0x3a/0xf0
tcp_sendmsg+0x33/0x40
____sys_sendmsg+0x2f2/0x490
__sys_sendmsg+0x184/0x230
do_syscall_64+0x3d/0x90
Avoid calling __TCP_INC_STATS() with will touch per-cpu variables. Use
TCP_INC_STATS() which is safe to be called from context switch.
Fixes: 8336886f78 ("tcp: TCP Fast Open Server - support TFO listeners")
Signed-off-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20230308190745.780221-1-leitao@debian.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2068237
commit 9b65b17db72313b7a4fe9bc9502928c88be57986
Author: Talal Ahmad <talalahmad@google.com>
Date: Tue Nov 2 22:58:44 2021 -0400
net: avoid double accounting for pure zerocopy skbs
Track skbs containing only zerocopy data and avoid charging them to
kernel memory to correctly account the memory utilization for
msg_zerocopy. All of the data in such skbs is held in user pages which
are already accounted to user. Before this change, they are charged
again in kernel in __zerocopy_sg_from_iter. The charging in kernel is
excessive because data is not being copied into skb frags. This
excessive charging can lead to kernel going into memory pressure
state which impacts all sockets in the system adversely. Mark pure
zerocopy skbs with a SKBFL_PURE_ZEROCOPY flag and remove
charge/uncharge for data in such skbs.
Initially, an skb is marked pure zerocopy when it is empty and in
zerocopy path. skb can then change from a pure zerocopy skb to mixed
data skb (zerocopy and copy data) if it is at tail of write queue and
there is room available in it and non-zerocopy data is being sent in
the next sendmsg call. At this time sk_mem_charge is done for the pure
zerocopied data and the pure zerocopy flag is unmarked. We found that
this happens very rarely on workloads that pass MSG_ZEROCOPY.
A pure zerocopy skb can later be coalesced into normal skb if they are
next to each other in queue but this patch prevents coalescing from
happening. This avoids complexity of charging when skb downgrades from
pure zerocopy to mixed. This is also rare.
In sk_wmem_free_skb, if it is a pure zerocopy skb, an sk_mem_uncharge
for SKB_TRUESIZE(skb_end_offset(skb)) is done for sk_mem_charge in
tcp_skb_entail for an skb without data.
Testing with the msg_zerocopy.c benchmark between two hosts(100G nics)
with zerocopy showed that before this patch the 'sock' variable in
memory.stat for cgroup2 that tracks sum of sk_forward_alloc,
sk_rmem_alloc and sk_wmem_queued is around 1822720 and with this
change it is 0. This is due to no charge to sk_forward_alloc for
zerocopy data and shows memory utilization for kernel is lowered.
With this commit we don't see the warning we saw in previous commit
which resulted in commit 84882cf72cd774cf16fd338bdbf00f69ac9f9194.
Signed-off-by: Talal Ahmad <talalahmad@google.com>
Acked-by: Arjun Roy <arjunroy@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2068237
commit 03271f3a3594c0e88f68d8cfbec0ba250b2c538a
Author: Talal Ahmad <talalahmad@google.com>
Date: Fri Oct 29 22:05:41 2021 -0400
tcp: rename sk_wmem_free_skb
sk_wmem_free_skb() is only used by TCP.
Rename it to make this clear, and move its declaration to
include/net/tcp.h
Signed-off-by: Talal Ahmad <talalahmad@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Acked-by: Arjun Roy <arjunroy@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2160073
Upstream Status: linux.git
commit e0bb4ab9dfddd872622239f49fb2bd403b70853b
Author: Kuniyuki Iwashima <kuniyu@amazon.com>
Date: Wed Jul 20 09:50:22 2022 -0700
tcp: Fix a data-race around sysctl_tcp_min_tso_segs.
While reading sysctl_tcp_min_tso_segs, it can be changed concurrently.
Thus, we need to add READ_ONCE() to its reader.
Fixes: 95bd09eb27 ("tcp: TSO packets automatic sizing")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Guillaume Nault <gnault@redhat.com>
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2160073
Upstream Status: linux.git
commit 9fb90193fbd66b4c5409ef729fd081861f8b6351
Author: Kuniyuki Iwashima <kuniyu@amazon.com>
Date: Wed Jul 20 09:50:20 2022 -0700
tcp: Fix a data-race around sysctl_tcp_limit_output_bytes.
While reading sysctl_tcp_limit_output_bytes, it can be changed
concurrently. Thus, we need to add READ_ONCE() to its reader.
Fixes: 46d3ceabd8 ("tcp: TCP Small Queues")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Guillaume Nault <gnault@redhat.com>
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2160073
Upstream Status: linux.git
commit 1a63cb91f0c2fcdeced6d6edee8d1d886583d139
Author: Kuniyuki Iwashima <kuniyu@amazon.com>
Date: Mon Jul 18 10:26:49 2022 -0700
tcp: Fix a data-race around sysctl_tcp_retrans_collapse.
While reading sysctl_tcp_retrans_collapse, it can be changed
concurrently. Thus, we need to add READ_ONCE() to its reader.
Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Guillaume Nault <gnault@redhat.com>
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2160073
Upstream Status: linux.git
commit 4845b5713ab18a1bb6e31d1fbb4d600240b8b691
Author: Kuniyuki Iwashima <kuniyu@amazon.com>
Date: Mon Jul 18 10:26:48 2022 -0700
tcp: Fix data-races around sysctl_tcp_slow_start_after_idle.
While reading sysctl_tcp_slow_start_after_idle, it can be changed
concurrently. Thus, we need to add READ_ONCE() to its readers.
Fixes: 35089bb203 ("[TCP]: Add tcp_slow_start_after_idle sysctl.")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Guillaume Nault <gnault@redhat.com>
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2160073
Upstream Status: linux.git
commit 52e65865deb6a36718a463030500f16530eaab74
Author: Kuniyuki Iwashima <kuniyu@amazon.com>
Date: Mon Jul 18 10:26:45 2022 -0700
tcp: Fix a data-race around sysctl_tcp_early_retrans.
While reading sysctl_tcp_early_retrans, it can be changed concurrently.
Thus, we need to add READ_ONCE() to its reader.
Fixes: eed530b6c6 ("tcp: early retransmit")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Guillaume Nault <gnault@redhat.com>
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2160073
Upstream Status: linux.git
commit 3666f666e99600518ab20982af04a078bbdad277
Author: Kuniyuki Iwashima <kuniyu@amazon.com>
Date: Mon Jul 18 10:26:44 2022 -0700
tcp: Fix data-races around sysctl knobs related to SYN option.
While reading these knobs, they can be changed concurrently.
Thus, we need to add READ_ONCE() to their readers.
- tcp_sack
- tcp_window_scaling
- tcp_timestamps
Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Guillaume Nault <gnault@redhat.com>
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2149949
Upstream Status: linux.git
commit 39e24435a776e9de5c6dd188836cf2523547804b
Author: Kuniyuki Iwashima <kuniyu@amazon.com>
Date: Fri Jul 15 10:17:50 2022 -0700
tcp: Fix data-races around some timeout sysctl knobs.
While reading these sysctl knobs, they can be changed concurrently.
Thus, we need to add READ_ONCE() to their readers.
- tcp_retries1
- tcp_retries2
- tcp_orphan_retries
- tcp_fin_timeout
Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Guillaume Nault <gnault@redhat.com>
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2149949
Upstream Status: linux.git
commit 2a85388f1d94a9f8b5a529118a2c5eaa0520d85c
Author: Kuniyuki Iwashima <kuniyu@amazon.com>
Date: Wed Jul 13 13:52:05 2022 -0700
tcp: Fix a data-race around sysctl_tcp_probe_interval.
While reading sysctl_tcp_probe_interval, it can be changed concurrently.
Thus, we need to add READ_ONCE() to its reader.
Fixes: 05cbc0db03 ("ipv4: Create probe timer for tcp PMTU as per RFC4821")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Guillaume Nault <gnault@redhat.com>
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2149949
Upstream Status: linux.git
commit 92c0aa4175474483d6cf373314343d4e624e882a
Author: Kuniyuki Iwashima <kuniyu@amazon.com>
Date: Wed Jul 13 13:52:04 2022 -0700
tcp: Fix a data-race around sysctl_tcp_probe_threshold.
While reading sysctl_tcp_probe_threshold, it can be changed concurrently.
Thus, we need to add READ_ONCE() to its reader.
Fixes: 6b58e0a5f3 ("ipv4: Use binary search to choose tcp PMTU probe_size")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Guillaume Nault <gnault@redhat.com>
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2149949
Upstream Status: linux.git
commit 78eb166cdefcc3221c8c7c1e2d514e91a2eb5014
Author: Kuniyuki Iwashima <kuniyu@amazon.com>
Date: Wed Jul 13 13:52:02 2022 -0700
tcp: Fix data-races around sysctl_tcp_min_snd_mss.
While reading sysctl_tcp_min_snd_mss, it can be changed concurrently.
Thus, we need to add READ_ONCE() to its readers.
Fixes: 5f3e2bf008 ("tcp: add tcp_min_snd_mss sysctl")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Guillaume Nault <gnault@redhat.com>
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2149949
Upstream Status: linux.git
commit 88d78bc097cd8ebc6541e93316c9d9bf651b13e8
Author: Kuniyuki Iwashima <kuniyu@amazon.com>
Date: Wed Jul 13 13:52:01 2022 -0700
tcp: Fix data-races around sysctl_tcp_base_mss.
While reading sysctl_tcp_base_mss, it can be changed concurrently.
Thus, we need to add READ_ONCE() to its readers.
Fixes: 5d424d5a67 ("[TCP]: MTU probing")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Guillaume Nault <gnault@redhat.com>
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2149949
Upstream Status: linux.git
commit f47d00e077e7d61baf69e46dde3210c886360207
Author: Kuniyuki Iwashima <kuniyu@amazon.com>
Date: Wed Jul 13 13:52:00 2022 -0700
tcp: Fix data-races around sysctl_tcp_mtu_probing.
While reading sysctl_tcp_mtu_probing, it can be changed concurrently.
Thus, we need to add READ_ONCE() to its readers.
Fixes: 5d424d5a67 ("[TCP]: MTU probing")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Guillaume Nault <gnault@redhat.com>
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2149949
Upstream Status: linux.git
commit 12b8d9ca7e678abc48195294494f1815b555d658
Author: Kuniyuki Iwashima <kuniyu@amazon.com>
Date: Mon Jul 11 17:15:31 2022 -0700
tcp: Fix a data-race around sysctl_tcp_ecn_fallback.
While reading sysctl_tcp_ecn_fallback, it can be changed concurrently.
Thus, we need to add READ_ONCE() to its reader.
Fixes: 492135557d ("tcp: add rfc3168, section 6.1.1.1. fallback")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Guillaume Nault <gnault@redhat.com>
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2149949
Upstream Status: linux.git
commit 4785a66702f086cf2ea84bdbe6ec921f274bd9f2
Author: Kuniyuki Iwashima <kuniyu@amazon.com>
Date: Mon Jul 11 17:15:30 2022 -0700
tcp: Fix data-races around sysctl_tcp_ecn.
While reading sysctl_tcp_ecn, it can be changed concurrently.
Thus, we need to add READ_ONCE() to its readers.
Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Guillaume Nault <gnault@redhat.com>
Merge conflicts:
-----------------
arch/x86/net/bpf_jit_comp.c
- bpf_arch_text_poke()
HEAD(!1464) contains b73b002f7f ("x86/ibt,bpf: Add ENDBR instructions to prologue and trampoline")
Resolved in favour of !1464, but keep the return statement from !1477
MR: https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-9/-/merge_requests/1477
Bugzilla: https://bugzilla.redhat.com/2120966
Rebase BPF and XDP to the upstream kernel version 5.18
Patch applied, then reverted:
```
544356 selftests/bpf: switch to new libbpf XDP APIs
0bfb95 selftests, bpf: Do not yet switch to new libbpf XDP APIs
```
Taken in the perf rebase:
```
23fcfc perf: use generic bpf_program__set_type() to set BPF prog type
```
Unsuported arches:
```
5c1011 libbpf: Fix riscv register names
cf0b5b libbpf: Fix accessing syscall arguments on riscv
```
Depends on changes of other subsystems:
```
7fc8c3 s390/bpf: encode register within extable entry
aebfd1 x86/ibt,ftrace: Search for __fentry__ location
589127 x86/ibt,bpf: Add ENDBR instructions to prologue and trampoline
```
Broken selftest:
```
edae34 selftests net: add UDP GRO fraglist + bpf self-tests
cf6783 selftests net: fix bpf build error
7b92aa selftests net: fix kselftest net fatal error
```
Out of scope:
```
baebdf net: dev: Makes sure netif_rx() can be invoked in any context.
5c8166 kbuild: replace $(if A,A,B) with $(or A,B)
1a97ce perf maps: Use a pointer for kmaps
967747 uaccess: remove CONFIG_SET_FS
42b01a s390: always use the packed stack layout
bf0882 flow_dissector: Add support for HSR
d09a30 s390/extable: move EX_TABLE define to asm-extable.h
3d6671 s390/extable: convert to relative table with data
4efd41 s390: raise minimum supported machine generation to z10
f65e58 flow_dissector: Add support for HSRv0
1a6d7a netdevsim: Introduce support for L3 offload xstats
9b1894 selftests: netdevsim: hw_stats_l3: Add a new test
84005b perf ftrace latency: Add -n/--use-nsec option
36c4a7 kasan, arm64: don't tag executable vmalloc allocations
8df013 docs: netdev: move the netdev-FAQ to the process pages
4d4d00 perf tools: Update copy of libbpf's hashmap.c
0df6ad perf evlist: Rename cpus to user_requested_cpus
1b8089 flow_dissector: fix false-positive __read_overflow2_field() warning
0ae065 perf build: Fix check for btf__load_from_kernel_by_id() in libbpf
8994e9 perf test bpf: Skip test if clang is not present
735346 perf build: Fix btf__load_from_kernel_by_id() feature check
f037ac s390/stack: merge empty stack frame slots
335220 docs: netdev: update maintainer-netdev.rst reference
a0b098 s390/nospec: remove unneeded header includes
34513a netdevsim: Fix hwstats debugfs file permissions
```
Signed-off-by: Jerome Marchand <jmarchan@redhat.com>
Approved-by: John W. Linville <linville@redhat.com>
Approved-by: Wander Lairson Costa <wander@redhat.com>
Approved-by: Torez Smith <torez@redhat.com>
Approved-by: Jan Stancek <jstancek@redhat.com>
Approved-by: Prarit Bhargava <prarit@redhat.com>
Approved-by: Felix Maurer <fmaurer@redhat.com>
Approved-by: Viktor Malik <vmalik@redhat.com>
Signed-off-by: Frantisek Hrbata <fhrbata@redhat.com>
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2137858
Upstream Status: net.git commit c4ee118561a0
commit c4ee118561a0f74442439b7b5b486db1ac1ddfeb
Author: Eric Dumazet <edumazet@google.com>
Date: Tue Jun 14 10:17:33 2022 -0700
tcp: fix over estimation in sk_forced_mem_schedule()
sk_forced_mem_schedule() has a bug similar to ones fixed
in commit 7c80b038d23e ("net: fix sk_wmem_schedule() and
sk_rmem_schedule() errors")
While this bug has little chance to trigger in old kernels,
we need to fix it before the following patch.
Fixes: d83769a580 ("tcp: fix possible deadlock in tcp_send_fin()")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Reviewed-by: Wei Wang <weiwan@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2137858
Upstream Status: net.git commit 0f1e4d06591d
commit 0f1e4d06591d0a7907c71f7b6d1c79f8a4de8098
Author: Kuniyuki Iwashima <kuniyu@amazon.com>
Date: Wed Jul 20 09:50:19 2022 -0700
tcp: Fix data-races around sysctl_tcp_workaround_signed_windows.
While reading sysctl_tcp_workaround_signed_windows, it can be changed
concurrently. Thus, we need to add READ_ONCE() to its readers.
Fixes: 15d99e02ba ("[TCP]: sysctl to allow TCP window > 32767 sans wscale")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2137858
Upstream Status: net.git commit 100fdd1faf50
commit 100fdd1faf50557558e2911af4be32e515cb8036
Author: Eric Dumazet <edumazet@google.com>
Date: Wed Jun 8 23:34:07 2022 -0700
net: remove SK_MEM_QUANTUM and SK_MEM_QUANTUM_SHIFT
Due to memcg interface, SK_MEM_QUANTUM is effectively PAGE_SIZE.
This might change in the future, but it seems better to avoid the
confusion.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2136491
Upstream Status: net-next.git commit 4d8f24eeedc5
commit 4d8f24eeedc58d5f87b650ddda73c16e8ba56559
Author: Wei Wang <weiwan@google.com>
Date: Thu Jul 21 20:44:04 2022 +0000
Revert "tcp: change pingpong threshold to 3"
This reverts commit 4a41f453be.
This to-be-reverted commit was meant to apply a stricter rule for the
stack to enter pingpong mode. However, the condition used to check for
interactive session "before(tp->lsndtime, icsk->icsk_ack.lrcvtime)" is
jiffy based and might be too coarse, which delays the stack entering
pingpong mode.
We revert this patch so that we no longer use the above condition to
determine interactive session, and also reduce pingpong threshold to 1.
Fixes: 4a41f453be ("tcp: change pingpong threshold to 3")
Reported-by: LemmyHuang <hlm3280@163.com>
Suggested-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Wei Wang <weiwan@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20220721204404.388396-1-weiwan@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2136491
Upstream Status: net-next.git commit f4ce91ce12a7
commit f4ce91ce12a7c6ead19b128ffa8cff6e3ded2a14
Author: Neal Cardwell <ncardwell@google.com>
Date: Wed Sep 28 16:03:31 2022 -0400
tcp: fix tcp_cwnd_validate() to not forget is_cwnd_limited
This commit fixes a bug in the tracking of max_packets_out and
is_cwnd_limited. This bug can cause the connection to fail to remember
that is_cwnd_limited is true, causing the connection to fail to grow
cwnd when it should, causing throughput to be lower than it should be.
The following event sequence is an example that triggers the bug:
(a) The connection is cwnd_limited, but packets_out is not at its
peak due to TSO deferral deciding not to send another skb yet.
In such cases the connection can advance max_packets_seq and set
tp->is_cwnd_limited to true and max_packets_out to a small
number.
(b) Then later in the round trip the connection is pacing-limited (not
cwnd-limited), and packets_out is larger. In such cases the
connection would raise max_packets_out to a bigger number but
(unexpectedly) flip tp->is_cwnd_limited from true to false.
This commit fixes that bug.
One straightforward fix would be to separately track (a) the next
window after max_packets_out reaches a maximum, and (b) the next
window after tp->is_cwnd_limited is set to true. But this would
require consuming an extra u32 sequence number.
Instead, to save space we track only the most important
information. Specifically, we track the strongest available signal of
the degree to which the cwnd is fully utilized:
(1) If the connection is cwnd-limited then we remember that fact for
the current window.
(2) If the connection not cwnd-limited then we track the maximum
number of outstanding packets in the current window.
In particular, note that the new logic cannot trigger the buggy
(a)/(b) sequence above because with the new logic a condition where
tp->packets_out > tp->max_packets_out can only trigger an update of
tp->is_cwnd_limited if tp->is_cwnd_limited is false.
This first showed up in a testing of a BBRv2 dev branch, but this
buggy behavior highlighted a general issue with the
tcp_cwnd_validate() logic that can cause cwnd to fail to increase at
the proper rate for any TCP congestion control, including Reno or
CUBIC.
Fixes: ca8a226343 ("tcp: make cwnd-limited checks measurement-based, and gentler")
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Kevin(Yudong) Yang <yyd@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2136491
Upstream Status: net-next.git commit 0a375c822497
commit 0a375c822497ed6ad6b5da0792a12a6f1af10c0b
Author: Eric Dumazet <edumazet@google.com>
Date: Mon May 30 14:37:13 2022 -0700
tcp: tcp_rtx_synack() can be called from process context
Laurent reported the enclosed report [1]
This bug triggers with following coditions:
0) Kernel built with CONFIG_DEBUG_PREEMPT=y
1) A new passive FastOpen TCP socket is created.
This FO socket waits for an ACK coming from client to be a complete
ESTABLISHED one.
2) A socket operation on this socket goes through lock_sock()
release_sock() dance.
3) While the socket is owned by the user in step 2),
a retransmit of the SYN is received and stored in socket backlog.
4) At release_sock() time, the socket backlog is processed while
in process context.
5) A SYNACK packet is cooked in response of the SYN retransmit.
6) -> tcp_rtx_synack() is called in process context.
Before blamed commit, tcp_rtx_synack() was always called from BH handler,
from a timer handler.
Fix this by using TCP_INC_STATS() & NET_INC_STATS()
which do not assume caller is in non preemptible context.
[1]
BUG: using __this_cpu_add() in preemptible [00000000] code: epollpep/2180
caller is tcp_rtx_synack.part.0+0x36/0xc0
CPU: 10 PID: 2180 Comm: epollpep Tainted: G OE 5.16.0-0.bpo.4-amd64 #1 Debian 5.16.12-1~bpo11+1
Hardware name: Supermicro SYS-5039MC-H8TRF/X11SCD-F, BIOS 1.7 11/23/2021
Call Trace:
<TASK>
dump_stack_lvl+0x48/0x5e
check_preemption_disabled+0xde/0xe0
tcp_rtx_synack.part.0+0x36/0xc0
tcp_rtx_synack+0x8d/0xa0
? kmem_cache_alloc+0x2e0/0x3e0
? apparmor_file_alloc_security+0x3b/0x1f0
inet_rtx_syn_ack+0x16/0x30
tcp_check_req+0x367/0x610
tcp_rcv_state_process+0x91/0xf60
? get_nohz_timer_target+0x18/0x1a0
? lock_timer_base+0x61/0x80
? preempt_count_add+0x68/0xa0
tcp_v4_do_rcv+0xbd/0x270
__release_sock+0x6d/0xb0
release_sock+0x2b/0x90
sock_setsockopt+0x138/0x1140
? __sys_getsockname+0x7e/0xc0
? aa_sk_perm+0x3e/0x1a0
__sys_setsockopt+0x198/0x1e0
__x64_sys_setsockopt+0x21/0x30
do_syscall_64+0x38/0xc0
entry_SYSCALL_64_after_hwframe+0x44/0xae
Fixes: 168a8f5805 ("tcp: TCP Fast Open Server - main code path")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Laurent Fasnacht <laurent.fasnacht@proton.ch>
Acked-by: Neal Cardwell <ncardwell@google.com>
Link: https://lore.kernel.org/r/20220530213713.601888-1-eric.dumazet@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2139501
commit 7c4e983c4f3cf94fcd879730c6caa877e0768a4d
Author: Alexander Duyck <alexanderduyck@fb.com>
Date: Fri May 13 11:33:57 2022 -0700
net: allow gso_max_size to exceed 65536
The code for gso_max_size was added originally to allow for debugging and
workaround of buggy devices that couldn't support TSO with blocks 64K in
size. The original reason for limiting it to 64K was because that was the
existing limits of IPv4 and non-jumbogram IPv6 length fields.
With the addition of Big TCP we can remove this limit and allow the value
to potentially go up to UINT_MAX and instead be limited by the tso_max_size
value.
So in order to support this we need to go through and clean up the
remaining users of the gso_max_size value so that the values will cap at
64K for non-TCPv6 flows. In addition we can clean up the GSO_MAX_SIZE value
so that 64K becomes GSO_LEGACY_MAX_SIZE and UINT_MAX will now be the upper
limit for GSO_MAX_SIZE.
v6: (edumazet) fixed a compile error if CONFIG_IPV6=n,
in a new sk_trim_gso_size() helper.
netif_set_tso_max_size() caps the requested TSO size
with GSO_MAX_SIZE.
Signed-off-by: Alexander Duyck <alexanderduyck@fb.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ivan Vecera <ivecera@redhat.com>
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2139501
commit ab14f1802cfb2d7ca120bbf48e3ba6712314ffc3
Author: David Ahern <dsahern@kernel.org>
Date: Mon Jan 24 19:45:11 2022 -0700
net: Adjust sk_gso_max_size once when set
sk_gso_max_size is set based on the dst dev. Both users of it
adjust the value by the same offset - (MAX_TCP_HEADER + 1). Rather
than compute the same adjusted value on each call do the adjustment
once when set.
Signed-off-by: David Ahern <dsahern@kernel.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20220125024511.27480-1-dsahern@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Ivan Vecera <ivecera@redhat.com>
Bugzilla: https://bugzilla.redhat.com/2120966
Conflicts:
- [minor] different context in tcp_fragment() due to missing
a52fe46ef160 ("tcp: factorize ip_summed setting")
commit a1ac9c8acec1605c6b43af418f79facafdced680
Author: Martin KaFai Lau <kafai@fb.com>
Date: Wed Mar 2 11:55:25 2022 -0800
net: Add skb->mono_delivery_time to distinguish mono delivery_time from (rcv) timestamp
skb->tstamp was first used as the (rcv) timestamp.
The major usage is to report it to the user (e.g. SO_TIMESTAMP).
Later, skb->tstamp is also set as the (future) delivery_time (e.g. EDT in TCP)
during egress and used by the qdisc (e.g. sch_fq) to make decision on when
the skb can be passed to the dev.
Currently, there is no way to tell skb->tstamp having the (rcv) timestamp
or the delivery_time, so it is always reset to 0 whenever forwarded
between egress and ingress.
While it makes sense to always clear the (rcv) timestamp in skb->tstamp
to avoid confusing sch_fq that expects the delivery_time, it is a
performance issue [0] to clear the delivery_time if the skb finally
egress to a fq@phy-dev. For example, when forwarding from egress to
ingress and then finally back to egress:
tcp-sender => veth@netns => veth@hostns => fq@eth0@hostns
^ ^
reset rest
This patch adds one bit skb->mono_delivery_time to flag the skb->tstamp
is storing the mono delivery_time (EDT) instead of the (rcv) timestamp.
The current use case is to keep the TCP mono delivery_time (EDT) and
to be used with sch_fq. A latter patch will also allow tc-bpf@ingress
to read and change the mono delivery_time.
In the future, another bit (e.g. skb->user_delivery_time) can be added
for the SCM_TXTIME where the clock base is tracked by sk->sk_clockid.
[ This patch is a prep work. The following patches will
get the other parts of the stack ready first. Then another patch
after that will finally set the skb->mono_delivery_time. ]
skb_set_delivery_time() function is added. It is used by the tcp_output.c
and during ip[6] fragmentation to assign the delivery_time to
the skb->tstamp and also set the skb->mono_delivery_time.
A note on the change in ip_send_unicast_reply() in ip_output.c.
It is only used by TCP to send reset/ack out of a ctl_sk.
Like the new skb_set_delivery_time(), this patch sets
the skb->mono_delivery_time to 0 for now as a place
holder. It will be enabled in a latter patch.
A similar case in tcp_ipv6 can be done with
skb_set_delivery_time() in tcp_v6_send_response().
[0] (slide 22): https://linuxplumbersconf.org/event/11/contributions/953/attachments/867/1658/LPC_2021_BPF_Datapath_Extensions.pdf
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jiri Benc <jbenc@redhat.com>
Bugzilla: https://bugzilla.redhat.com/2120966
commit cb6cd2cec799356e5e2f75a8591894599a6ad49d
Author: Akhmat Karakotov <hmukos@yandex-team.ru>
Date: Mon Jan 31 16:31:25 2022 +0300
tcp: Change SYN ACK retransmit behaviour to account for rehash
Disabling rehash behavior did not affect SYN ACK retransmits because hash
was forcefully changed bypassing the sk_rethink_hash function. This patch
adds a condition which checks for rehash mode before resetting hash.
Signed-off-by: Akhmat Karakotov <hmukos@yandex-team.ru>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jiri Benc <jbenc@redhat.com>
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2134161
Tested: LNST, Tier1
Upstream commit:
commit 1227c1771dd2ad44318aa3ab9e3a293b3f34ff2a
Author: Kuniyuki Iwashima <kuniyu@amazon.com>
Date: Tue Aug 23 10:46:44 2022 -0700
net: Fix data-races around sysctl_[rw]mem_(max|default).
While reading sysctl_[rw]mem_(max|default), they can be changed
concurrently. Thus, we need to add READ_ONCE() to its readers.
Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2134161
Tested: LNST, Tier1
Conflicts: different context in __tcp_grow_window() as rhel-9 \
lacks upstream commit 240bfd134c592 ("tcp: tweak len/truesize \
ratio for coalesce candidates")
Upstream commit:
commit 02739545951ad4c1215160db7fbf9b7a918d3c0b
Author: Kuniyuki Iwashima <kuniyu@amazon.com>
Date: Fri Jul 22 11:22:00 2022 -0700
net: Fix data-races around sysctl_[rw]mem(_offset)?.
While reading these sysctl variables, they can be changed concurrently.
Thus, we need to add READ_ONCE() to their readers.
- .sysctl_rmem
- .sysctl_rwmem
- .sysctl_rmem_offset
- .sysctl_wmem_offset
- sysctl_tcp_rmem[1, 2]
- sysctl_tcp_wmem[1, 2]
- sysctl_decnet_rmem[1]
- sysctl_decnet_wmem[1]
- sysctl_tipc_rmem[1]
Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2101465
Tested: LNST, Tier1
Upstream commit:
commit 40570375356c874b1578e05c1dcc3ff7c1322dbe
Author: Eric Dumazet <edumazet@google.com>
Date: Tue Apr 5 16:35:38 2022 -0700
tcp: add accessors to read/set tp->snd_cwnd
We had various bugs over the years with code
breaking the assumption that tp->snd_cwnd is greater
than zero.
Lately, syzbot reported the WARN_ON_ONCE(!tp->prior_cwnd) added
in commit 8b8a321ff7 ("tcp: fix zero cwnd in tcp_cwnd_reduction")
can trigger, and without a repro we would have to spend
considerable time finding the bug.
Instead of complaining too late, we want to catch where
and when tp->snd_cwnd is set to an illegal value.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Suggested-by: Yuchung Cheng <ycheng@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Acked-by: Yuchung Cheng <ycheng@google.com>
Link: https://lore.kernel.org/r/20220405233538.947344-1-eric.dumazet@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
MR: https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-9/-/merge_requests/888
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2089885
Tested: LNST, Tier1 and vs bz reproducer
when the MPTCP tput is CPU bound, and the used links are much faster then the CPU limits, the MPTCP tput is unstable as the MPTCP-level congestion window sharing has currently some glitches: patch 1/5 ensures the sharing affects even the announced window, patch 3/5 and 4/5 takes care of concurrent announced window updates. The remaining patches add more MIBs counter for introspection's sake
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Approved-by: Florian Westphal <fwestpha@redhat.com>
Approved-by: Davide Caratti <dcaratti@redhat.com>
Signed-off-by: Patrick Talbert <ptalbert@redhat.com>
CKI Backport Bot
Paolo Abeni
Lucas Zampieri
Antoine Tenart
Xin Long
Florian Westphal
Scott Weaver
Jan Stancek
Felix Maurer
Jeff Moyer
Guillaume Nault
Frantisek Hrbata
Davide Caratti
Ivan Vecera
Jiri Benc
Patrick Talbert