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Jakub Kicinski 2a06576b61 selftests: tc_actions: don't dump 2MB of \0 to stdout
[ Upstream commit 32b70e6203 ]

Since we started running selftests in NIPA we have been seeing
tc_actions.sh generate a soft lockup warning on ~20% of the runs.
On the pre-netdev foundation setup it was actually a missed irq
splat from the console. Now it's either that or a lockup.

I initially suspected a socket locking issue since the test
is exercising local loopback with act_mirred.
After hours of staring at this I noticed in strace that ncat
when -o $file is specified _both_ saves the output to the file
and still prints it to stdout. Because the file being sent
is constructed with:

  dd conv=sparse status=none if=/dev/zero bs=1M count=2 of=$mirred
                                ^^^^^^^^^

the data printed is all \0. Most terminals don't display nul
characters (and neither does vng output capture save them).
But QEMU's serial console still has to poke them thru which
is very slow and causes the lockup (if the file is >600kB).

Replace the '-o $file' with '> $file'. This speeds the test up
from 2m20s to 18s on debug kernels, and prevents the warnings.

Fixes: ca22da2fbd ("act_mirred: use the backlog for nested calls to mirred ingress")
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20260214035159.2119699-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2026-02-26 14:59:40 -08:00
arch mips: LOONGSON32: drop a dangling Kconfig symbol 2026-02-26 14:59:35 -08:00
block block,bfq: fix aux stat accumulation destination 2026-02-11 13:41:47 +01:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto crypto: authencesn - reject too-short AAD (assoclen<8) to match ESP/ESN spec 2026-01-30 10:32:12 +01:00
Documentation dpll: add phase-adjust-gran pin attribute 2026-02-26 14:59:22 -08:00
drivers xen-netback: reject zero-queue configuration from guest 2026-02-26 14:59:39 -08:00
fs fs/ntfs3: Fix slab-out-of-bounds read in DeleteIndexEntryRoot 2026-02-26 14:59:36 -08:00
include ipv6: fix a race in ip6_sock_set_v6only() 2026-02-26 14:59:39 -08:00
init printk changes for 6.18 2025-10-04 11:13:11 -07:00
io_uring io_uring/cancel: de-unionize file and user_data in struct io_cancel_data 2026-02-26 14:59:36 -08:00
ipc ipc: don't audit capability check in ipc_permissions() 2026-02-26 14:59:19 -08:00
kernel bpf: Add a map/btf from a fd array more consistently 2026-02-26 14:59:38 -08:00
lib objpool: fix the overestimation of object pooling metadata size 2026-02-26 14:59:36 -08:00
LICENSES LICENSES: Replace the obsolete address of the FSF in the GFDL-1.2 2025-07-24 11:15:39 +02:00
mm mm/slab: fix false lockdep warning in __kfree_rcu_sheaf() 2026-02-26 14:59:14 -08:00
net ping: annotate data-races in ping_lookup() 2026-02-26 14:59:40 -08:00
rust rust: task: restrict Task::group_leader() to current 2026-02-26 14:59:18 -08:00
samples samples/ftrace: Adjust LoongArch register restore order in direct calls 2026-01-08 10:17:11 +01:00
scripts scripts: generate_rust_analyzer: Add compiler_builtins -> core dep 2026-02-06 16:57:42 +01:00
security evm: Use ordered xattrs list to calculate HMAC in evm_init_hmac() 2026-02-26 14:59:14 -08:00
sound ASoC: SDCA: Handle volatile controls correctly 2026-02-26 14:59:15 -08:00
tools selftests: tc_actions: don't dump 2MB of \0 to stdout 2026-02-26 14:59:40 -08:00
usr gen_init_cpio: Ignore fsync() returning EINVAL on pipes 2025-10-07 09:53:05 -07:00
virt KVM: Don't clobber irqfd routing type when deassigning irqfd 2026-02-11 13:41:44 +01:00
.clang-format memblock: drop for_each_free_mem_pfn_range_in_zone_from() 2025-09-14 08:49:03 +03:00
.clippy.toml rust: clean Rust 1.88.0's warning about clippy::disallowed_macros configuration 2025-05-07 00:11:47 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.editorconfig .editorconfig: remove trim_trailing_whitespace option 2024-06-13 16:47:52 +02:00
.get_maintainer.ignore MAINTAINERS: remove Alyssa Rosenzweig 2025-09-18 21:17:31 +02:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore .gitignore: ignore compile_commands.json globally 2025-08-12 15:53:55 -07:00
.mailmap 8 hotfixes. 4 are cc:stable, 7 are against mm/. 2025-11-26 12:38:05 -08:00
.pylintrc tools: docs: parse-headers.py: move it from sphinx dir 2025-08-29 15:54:42 -06:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: mark ISDN subsystem as orphan 2025-10-27 17:49:45 -07:00
Kbuild sched: Make migrate_{en,dis}able() inline 2025-09-25 09:57:16 +02:00
Kconfig io_uring: Rename KConfig to Kconfig 2025-02-19 14:53:27 -07:00
MAINTAINERS soc: fixes for 6.18, part 4 2025-11-28 09:57:31 -08:00
Makefile kbuild: Add objtool to top-level clean target 2026-02-26 14:59:36 -08:00
README README: Fix spelling 2024-03-18 03:36:32 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.