Greeting,

FYI, we noticed the following commit (built with gcc-11):

commit: 4bfe744ff1644fbc0a991a2677dc874475dd6776 ("tcp: fix potential xmit stalls caused by TCP_NOTSENT_LOWAT")
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master

in testcase: packetdrill
version: packetdrill-x86_64-329d89e-1_20220824
with following parameters:



on test machine: 8 threads 1 sockets Intel(R) Core(TM) i7-7700 CPU @ 3.60GHz (Kaby Lake) with 32G memory

caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace):


If you fix the issue, kindly add following tag
| Reported-by: kernel test robot <oliver.sang@intel.com>
| Link: https://lore.kernel.org/r/202209201359.3f33d97f-oliver.sang@intel.com


we actually also observed other tests failed on this commit but pass on parent:
(more details are in attached dmesg and 'packetdrill' file)

=========================================================================================
tbox_group/testcase/rootfs/kconfig/compiler:
  lkp-kbl-d01/packetdrill/debian-11.1-x86_64-20220510.cgz/x86_64-rhel-8.3-func/gcc-11

1fcb8fb3522f5b0f 4bfe744ff1644fbc0a991a2677d
---------------- ---------------------------
       fail:runs  %reproduction    fail:runs
           |             |             |
           :30         100%          30:30    packetdrill.packetdrill/gtests/net/tcp/epoll/epoll_out_edge_default_notsent_lowat_ipv4-mapped-v6.fail
           :30         100%          30:30    packetdrill.packetdrill/gtests/net/tcp/epoll/epoll_out_edge_default_notsent_lowat_ipv4.fail
           :30         100%          30:30    packetdrill.packetdrill/gtests/net/tcp/epoll/epoll_out_edge_ipv4-mapped-v6.fail
           :30         100%          30:30    packetdrill.packetdrill/gtests/net/tcp/epoll/epoll_out_edge_ipv4.fail
           :30         100%          30:30    packetdrill.packetdrill/gtests/net/tcp/epoll/epoll_out_edge_notsent_lowat_ipv4-mapped-v6.fail
           :30         100%          30:30    packetdrill.packetdrill/gtests/net/tcp/epoll/epoll_out_edge_notsent_lowat_ipv4.fail


stdout: 
stderr: 
FAIL [/lkp/benchmarks/packetdrill/gtests/net/tcp/epoll/epoll_out_edge.pkt (ipv4)]
stdout: 
stderr: 
FAIL [/lkp/benchmarks/packetdrill/gtests/net/tcp/epoll/epoll_out_edge_default_notsent_lowat.pkt (ipv4-mapped-v6)]



To reproduce:

        git clone https://github.com/intel/lkp-tests.git
        cd lkp-tests
        sudo bin/lkp install job.yaml           # job file is attached in this email
        bin/lkp split-job --compatible job.yaml # generate the yaml file for lkp run
        sudo bin/lkp run generated-yaml-file

        # if come across any failure that blocks the test,
        # please remove ~/.lkp and /lkp dir to run from a clean state.



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