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From 8bdc512d2651b4600f7e744b06633a7524b64346 Mon Sep 17 00:00:00 2001
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From: Lennart Poettering <lennart@poettering.net>
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Date: Mon, 12 Oct 2020 16:31:42 +0200
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Subject: [PATCH] sysctl: set kernel.core_pipe_limit=16
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We need to make sure that our coredump pattern handler manages to read
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process metadata from /proc/$PID/ before the kernel reaps the crashed
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process. By default the kernel will reap the process as soon as it can.
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By setting kernel.core_pipe_limit to a non-zero the kernel will wait for
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userspace to finish before reaping.
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We'll set the value to 16, which allows 16 crashes to be
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processed in parallel. This matches the MaxConnections= setting in
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systemd-coredump.socket.
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See: #17301
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(This doesn't close 17301, since we probably should also gracefully
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handle if /proc/$PID/ vanished already while our coredump handler runs,
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just in case people loclly set the sysctl back to zero. i.e. we should
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collect what we can and rather issue an incomplete log record than
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none.)
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(cherry picked from commit 2a9b9323cd844baae3229e9dba67e478bee70654)
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Resolves: #1949729
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---
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sysctl.d/50-coredump.conf.in | 11 +++++++++++
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1 file changed, 11 insertions(+)
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diff --git a/sysctl.d/50-coredump.conf.in b/sysctl.d/50-coredump.conf.in
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index ccd5c2cc56..8d6fbb718c 100644
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--- a/sysctl.d/50-coredump.conf.in
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+++ b/sysctl.d/50-coredump.conf.in
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@@ -10,3 +10,14 @@
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# setting below.
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kernel.core_pattern=|@rootlibexecdir@/systemd-coredump %P %u %g %s %t %c %h %e
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+
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+# Allow that 16 coredumps are dispatched in parallel by the kernel. We want to
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+# be able to collect process metadata from /proc/%P/ while processing
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+# coredumps, and thus need to make sure the crashed processes are not reaped
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+# until we finished collecting what we need. The kernel default for this sysctl
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+# is "0" which means the kernel doesn't wait for userspace processes to finish
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+# processing before reaping the crashed processes — by setting this higher the
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+# kernel will delay reaping until we are done, but only for the specified
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+# number of crashes in parallel. The value of 16 is chosen to match
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+# systemd-coredump.socket's MaxConnections= value.
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+kernel.core_pipe_limit=16
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