Your message dated Thu, 20 Feb 2025 11:16:13 +0100 (CET)
with message-id <20250220101613.ef7d9be2...@eldamar.lan>
and subject line Closing this bug (BTS maintenance for src:linux bugs)
has caused the Debian Bug report #798088,
regarding linux: /proc/sys/kernel/random/write_wakeup_threshold can be set too
an unreachable amount of entropy
to be marked as done.
This means that you claim that the problem has been dealt with.
If this is not the case it is now your responsibility to reopen the
Bug report if necessary, and/or fix the problem forthwith.
(NB: If you are a system administrator and have no idea what this
message is talking about, this may indicate a serious mail system
misconfiguration somewhere. Please contact ow...@bugs.debian.org
immediately.)
--
798088: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=798088
Debian Bug Tracking System
Contact ow...@bugs.debian.org with problems
--- Begin Message ---
Package: linux-image-4.1.0-2-amd64
Severity: normal
Hi!
I was reported #740117 on haveged. The bug is basically that when the
entropy watermark is set too high, haveged will busy loop like hell.
I've worked around the issue in haveged the same way rngd does, but I
believe the problem is in the kernel.
Both haveged and rngd loop like follows: block trying to write to
/dev/random, fetch entropy, feed the kernel and go back blocking again.
Process trying to write to /dev/random will be blocked until the
available goes below the value defined in
/proc/sys/kernel/random/write_wakeup_threshold.
Even if its value is bounded by the entropy pool size, it can still be
set to a value that will always allow writes to /dev/random. That's
because the amount of entropy is asymptotical as explained in the
driver [1].
From my limited understanding of the driver, I believe
the maximum value that should be allowed to write_wakeup_threshold is
actually 3/4 of size of the pool instead of its full size.
[1]:
https://sources.debian.net/src/linux/4.1.6-1/drivers/char/random.c/?hl=613:631#L613
--
Lunar .''`.
lu...@debian.org : :â’¶ : # apt-get install anarchism
`. `'`
`-
signature.asc
Description: Digital signature
--- End Message ---
--- Begin Message ---
Hi
This bug was filed for a very old kernel or the bug is old itself
without resolution.
If you can reproduce it with
- the current version in unstable/testing
- the latest kernel from backports
please reopen the bug, see https://www.debian.org/Bugs/server-control
for details.
Regards,
Salvatore
--- End Message ---
