The description didn't really explain how the distribution mechanism
works exactly and the relationship of leaf and slice units.
Update the documentation and also explicitly explain the expected
behaviour as it is created by the memory_recursiveprot cgroup2 mount
option.
When available, enable memory_recursiveprot. Realistically it always
makes sense to delegate MemoryLow= and MemoryMin= to all children of a
slice/unit.
The kernel option is not enabled by default as it might cause
regressions in some setups. However, it is the better default in
general, and it results in a more flexible and obvious behaviour.
The alternative to using this option would be for user's to also set
DefaultMemoryLow= on slices when assigning MemoryLow=. However, this
makes the effect of MemoryLow= on some children less obvious, as it
could result in a lower protection rather than increasing it.
From the kernel documentation:
memory_recursiveprot
Recursively apply memory.min and memory.low protection to
entire subtrees, without requiring explicit downward
propagation into leaf cgroups. This allows protecting entire
subtrees from one another, while retaining free competition
within those subtrees. This should have been the default
behavior but is a mount-option to avoid regressing setups
relying on the original semantics (e.g. specifying bogusly
high 'bypass' protection values at higher tree levels).
This was added in kernel commit 8a931f801340c (mm: memcontrol:
recursive memory.low protection), which became available in 5.7 and was
subsequently fixed in kernel 5.7.7 (mm: memcontrol: handle div0 crash
race condition in memory.low).
This was needed before commit 16e4fd87c5 added a
mode that opens the log fds for every single log message. This mode is used in
execute.c since then making the explicit call to log_open unnecessary.
This basically reverts ea89a119cd.
glibc 2.26 lifted restrictions on search domains count or length to
unlimited. This has also been backported to 2.17 in some distributions (RHEL 7
and derivatives). Other softwares may have their own limits for search domains,
but we should not restrict what is written out any more.
https://sourceware.org/legacy-ml/libc-announce/2017/msg00001.html
This comes up occasionally with new users. The phrase "Logs begin ..." is
ambiguous because it can be taken to mean the logs being displayed or all logs
(the intended meaning). Let's rephrase this as "Journal begins ..." to make
this clearer.
This information was already available in the debug output, but I think it
is good to include it in the message in the table. This makes it easier to wrap
one's head around the allowlist/denylist filtering.
I am pretty sure /etc/hosts (i.e. an explicitly configured, local,
trusted database) should be useful for overriding the automatic
myhostname logic.
resolved's internal logic handles it that way and hence we should
suggest it in the NSS fallback line, too.
Let's also bring the factory file back into sync with what the docs say.
And update the prose a bit too, to actually match what we recommend.
Unprivileged test-fs-util fails on my system since /sys/dev/block is
inaccessible for unprivileged users, so let's skip encrypted path test if we
get EACCES or similar.
If we don't succeed on the first try it's because another process is
opening the same device. Do a microsleep for 2ms to increase the
chances it has completed the next time around the loop.
The symlink /dev/mapper/dm_name is created by udev after a mapper
device is set up. So libdevmapper/libcrypsetup might tell us that
a verity device exists, but the symlink we use as the source for
the mount operation might not be there yet.
Instead of falling back to a new unique device set up, wait for
the udev event matching on the expected devlink for at least 100ms
(after which the benefits of sharing a device in terms of setup
time start to disappear - on my production machines, opening a new
verity device seems to take between 150ms and 300ms)
This effectively makes little difference because we exit soon later
anyway, which will close the fds, too. However, it's still useful since
it means the parent will get EOF events on them in the order we process
things and isn't delayed to process the data from the pipes until the
child dies.
Let's use a proper table for outputting partition information. Let's
also put the general information about the image first, and the table
after that.
Moreover, dissect the image before showing any output, so that we can
early on return an error if the image is not valid.
Benjamin Berg
Lennart Poettering
Anita Zhang
Alyssa Ross
Nicolas Fella
Yu Watanabe
Zbigniew Jędrzejewski-Szmek
Franck Bui
Dimitri John Ledkov
Grant Mathews
Haochen Tong
Topi Miettinen
Michael Scherer
Luca Boccassi