[PATCH] acct(2): begin the deprecation of legacy BSD process accounting

[Jeff Layton <jlayton@kernel.org>]

As Christian points out [1], even though it's privileged, this interface
has a lot of footguns. There are better options these days (e.g. eBPF),
so it would be good to start discouraging its use and mark it as
deprecated.

[1]: https://lore.kernel.org/linux-fsdevel/20250212-giert-spannend-8893f1eaba7d@brauner/

Signed-off-by: Jeff Layton <jlayton@kernel.org>
---
I meant to send this months ago, but never got around to it. Let's at
least mark this as deprecated and see who complains. We could also
consider adding a pr_warn_once() that fires the first time someone calls
acct(2) if we want to kill this in a more near-term timeframe.
---
 init/Kconfig | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/init/Kconfig b/init/Kconfig
index fa79feb8fe57bb01d8ce8f35e33535709b57d452..160c1c4ef253593d62650cd5a53f3421bc9372d3 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -624,8 +624,9 @@ config SCHED_HW_PRESSURE
 	  arch_update_hw_pressure() and arch_scale_thermal_pressure().
 
 config BSD_PROCESS_ACCT
-	bool "BSD Process Accounting"
+	bool "BSD Process Accounting (DEPRECATED)"
 	depends on MULTIUSER
+	default n
 	help
 	  If you say Y here, a user level program will be able to instruct the
 	  kernel (via a special system call) to write process accounting
@@ -635,7 +636,9 @@ config BSD_PROCESS_ACCT
 	  command name, memory usage, controlling terminal etc. (the complete
 	  list is in the struct acct in <file:include/linux/acct.h>).  It is
 	  up to the user level program to do useful things with this
-	  information.  This is generally a good idea, so say Y.
+	  information.  This mechanism is antiquated and has significant
+	  scalability issues.  You probably want to use eBPF instead.  Say
+	  N unless you really need this.
 
 config BSD_PROCESS_ACCT_V3
 	bool "BSD Process Accounting version 3 file format"

---
base-commit: 7f98ab9da046865d57c102fd3ca9669a29845f67
change-id: 20260106-bsd-acct-c60be8e6ae62

Best regards,
-- 
Jeff Layton <jlayton@kernel.org>