c5330bdf7e
The bootup of the armsr target sometimes failed like this: ``` [ 0.762283] NET: Registered PF_INET6 protocol family [ 0.791987] workqueue: Failed to create a worker thread: -EAGAIN [ 0.801986] workqueue: Failed to create a rescuer kthread for wq "mld": -EAGAIN [ 0.964017] NET: Unregistered PF_INET6 protocol family ``` Increase the maximum number of threads the kernel allows. Link: https://github.com/openwrt/openwrt/pull/19376 Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
37 lines
1.3 KiB
Diff
37 lines
1.3 KiB
Diff
From a22c4c7bbfad3e93e717e16f6faf343259add27a Mon Sep 17 00:00:00 2001
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From: Hauke Mehrtens <hauke@hauke-m.de>
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Date: Fri, 27 Jun 2025 11:09:04 +0100
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Subject: [PATCH v2] kernel/fork: Increase minimum number of allowed threads
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A modern Linux system creates much more than 20 threads at bootup.
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When I booted up OpenWrt in qemu the system sometimes failed to boot up
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when it wanted to create the 419th thread. The VM had 128MB RAM and the
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calculation in set_max_threads() calculated that max_threads should be
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set to 419. When the system booted up it tried to notify the user space
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about every device it created because CONFIG_UEVENT_HELPER was set and
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used. I counted 1299 calls to call_usermodehelper_setup(), all of
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them try to create a new thread and call the userspace hotplug script in
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it.
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This fixes bootup of Linux on systems with low memory.
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I saw the problem with qemu 10.0.2 using these commands:
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qemu-system-aarch64 -machine virt -cpu cortex-a57 -nographic
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Cc: stable@vger.kernel.org
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Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
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---
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kernel/fork.c | 2 +-
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1 file changed, 1 insertion(+), 1 deletion(-)
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--- a/kernel/fork.c
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+++ b/kernel/fork.c
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@@ -115,7 +115,7 @@
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/*
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* Minimum number of threads to boot the kernel
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*/
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-#define MIN_THREADS 20
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+#define MIN_THREADS 600
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/*
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* Maximum number of threads
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