Re: [GIT PULL] sysctl changes for v6.6-rc1

From: Joel Granados
Date: Wed Sep 06 2023 - 08:35:35 EST

On Wed, Sep 06, 2023 at 01:58:49PM +0200, Alexey Gladkov wrote:
> On Tue, Aug 29, 2023 at 01:44:55PM -0700, Luis Chamberlain wrote:
> > The following changes since commit 06c2afb862f9da8dc5efa4b6076a0e48c3fbaaa5:
> >
> > Linux 6.5-rc1 (2023-07-09 13:53:13 -0700)
> >
> > are available in the Git repository at:
> >
> > git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux.git/ tags/sysctl-6.6-rc1
> >
> > for you to fetch changes up to 53f3811dfd5e39507ee3aaea1be09aabce8f9c98:
> >
> > sysctl: Use ctl_table_size as stopping criteria for list macro (2023-08-15 15:26:18 -0700)
> >
> > ----------------------------------------------------------------
> > sysctl-6.6-rc1
> >
> > Long ago we set out to remove the kitchen sink on kernel/sysctl.c arrays and
> > placings sysctls to their own sybsystem or file to help avoid merge conflicts.
> > Matthew Wilcox pointed out though that if we're going to do that we might as
> > well also *save* space while at it and try to remove the extra last sysctl
> > entry added at the end of each array, a sentintel, instead of bloating the
> > kernel by adding a new sentinel with each array moved.
> >
> > Doing that was not so trivial, and has required slowing down the moves of
> > kernel/sysctl.c arrays and measuring the impact on size by each new move.
> >
> > The complex part of the effort to help reduce the size of each sysctl is being
> > done by the patient work of el señor Don Joel Granados. A lot of this is truly
> > painful code refactoring and testing and then trying to measure the savings of
> > each move and removing the sentinels. Although Joel already has code which does
> > most of this work, experience with sysctl moves in the past shows is we need to
> > be careful due to the slew of odd build failures that are possible due to the
> > amount of random Kconfig options sysctls use.
> >
> > To that end Joel's work is split by first addressing the major housekeeping
> > needed to remove the sentinels, which is part of this merge request. The rest
> > of the work to actually remove the sentinels will be done later in future
> > kernel releases.
>
> This is very interesting for me. I'm also refactoring sysctl based on
> discussion with Linus a while ago.
>
> Could you please add me to the Cc in the next patches?
I just sent the next batch for this set for review. You can see it here
https://lore.kernel.org/all/20230906-jag-sysctl_remove_empty_elem_arch-v1-0-3935d4854248@xxxxxxxxxxx/
Will add you for the next ones.

Best

>
> > At first I was only going to send his first 7 patches of his patch series,
> > posted 1 month ago, but in retrospect due to the testing the changes have
> > received in linux-next and the minor changes they make this goes with the
> > entire set of patches Joel had planned: just sysctl house keeping. There are
> > networking changes but these are part of the house keeping too.
> >
> > The preliminary math is showing this will all help reduce the overall build
> > time size of the kernel and run time memory consumed by the kernel by about
> > ~64 bytes per array where we are able to remove each sentinel in the future.
> > That also means there is no more bloating the kernel with the extra ~64 bytes
> > per array moved as no new sentinels are created.
> >
> > Most of this has been in linux-next for about a month, the last 7 patches took
> > a minor refresh 2 week ago based on feedback.
> >
> > ----------------------------------------------------------------
> > Joel Granados (14):
> > sysctl: Prefer ctl_table_header in proc_sysctl
> > sysctl: Use ctl_table_header in list_for_each_table_entry
> > sysctl: Add ctl_table_size to ctl_table_header
> > sysctl: Add size argument to init_header
> > sysctl: Add a size arg to __register_sysctl_table
> > sysctl: Add size to register_sysctl
> > sysctl: Add size arg to __register_sysctl_init
> > sysctl: Add size to register_net_sysctl function
> > ax.25: Update to register_net_sysctl_sz
> > netfilter: Update to register_net_sysctl_sz
> > networking: Update to register_net_sysctl_sz
> > vrf: Update to register_net_sysctl_sz
> > sysctl: SIZE_MAX->ARRAY_SIZE in register_net_sysctl
> > sysctl: Use ctl_table_size as stopping criteria for list macro
> >
> > arch/arm64/kernel/armv8_deprecated.c | 2 +-
> > arch/s390/appldata/appldata_base.c | 2 +-
> > drivers/net/vrf.c | 3 +-
> > fs/proc/proc_sysctl.c | 90 +++++++++++++++++----------------
> > include/linux/sysctl.h | 31 +++++++++---
> > include/net/ipv6.h | 2 +
> > include/net/net_namespace.h | 10 ++--
> > ipc/ipc_sysctl.c | 4 +-
> > ipc/mq_sysctl.c | 4 +-
> > kernel/ucount.c | 5 +-
> > net/ax25/sysctl_net_ax25.c | 3 +-
> > net/bridge/br_netfilter_hooks.c | 3 +-
> > net/core/neighbour.c | 8 ++-
> > net/core/sysctl_net_core.c | 3 +-
> > net/ieee802154/6lowpan/reassembly.c | 8 ++-
> > net/ipv4/devinet.c | 3 +-
> > net/ipv4/ip_fragment.c | 3 +-
> > net/ipv4/route.c | 8 ++-
> > net/ipv4/sysctl_net_ipv4.c | 3 +-
> > net/ipv4/xfrm4_policy.c | 3 +-
> > net/ipv6/addrconf.c | 3 +-
> > net/ipv6/icmp.c | 5 ++
> > net/ipv6/netfilter/nf_conntrack_reasm.c | 3 +-
> > net/ipv6/reassembly.c | 3 +-
> > net/ipv6/route.c | 9 ++++
> > net/ipv6/sysctl_net_ipv6.c | 16 ++++--
> > net/ipv6/xfrm6_policy.c | 3 +-
> > net/mpls/af_mpls.c | 6 ++-
> > net/mptcp/ctrl.c | 3 +-
> > net/netfilter/ipvs/ip_vs_ctl.c | 8 ++-
> > net/netfilter/ipvs/ip_vs_lblc.c | 10 ++--
> > net/netfilter/ipvs/ip_vs_lblcr.c | 10 ++--
> > net/netfilter/nf_conntrack_standalone.c | 4 +-
> > net/netfilter/nf_log.c | 7 +--
> > net/rds/tcp.c | 3 +-
> > net/sctp/sysctl.c | 4 +-
> > net/smc/smc_sysctl.c | 3 +-
> > net/sysctl_net.c | 26 +++++++---
> > net/unix/sysctl_net_unix.c | 3 +-
> > net/xfrm/xfrm_sysctl.c | 8 ++-
> > 40 files changed, 222 insertions(+), 113 deletions(-)
>
> --
> Rgrds, legion
>

--

Joel Granados

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