From d9d25684e98d45322a9b7ff44beb4275ffdf1d74 Mon Sep 17 00:00:00 2001 From: Marc Herbert Date: Wed, 7 Jan 2026 20:21:32 +0000 Subject: [PATCH] docs: make kptr_restrict and hash_pointers reference each other vsprintf.c uses a mix of the `kernel.kptr_restrict` sysctl and the `hash_pointers` boot param to control pointer hashing. But that wasn't possible to tell without looking at the source code. They have a different focus and purpose. To avoid wasting the time of users trying to use one instead of the other, simply have them reference each other in the Documentation. Signed-off-by: Marc Herbert Acked-by: Randy Dunlap Signed-off-by: Jonathan Corbet Message-ID: <20260107-doc-hash-ptr-v2-1-cb4c161218d7@linux.intel.com> --- Documentation/admin-guide/kernel-parameters.txt | 3 +++ Documentation/admin-guide/sysctl/kernel.rst | 3 +++ 2 files changed, 6 insertions(+) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index f4a2bf906bf3c..8e3738d9588a6 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -1969,6 +1969,9 @@ Kernel parameters param "no_hash_pointers" is an alias for this mode. + For controlling hashing dynamically at runtime, + use the "kernel.kptr_restrict" sysctl instead. + hashdist= [KNL,NUMA] Large hashes allocated during boot are distributed across NUMA nodes. Defaults on for 64-bit NUMA, off otherwise. diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst index 239da22c4e28f..0315eb7ee6d40 100644 --- a/Documentation/admin-guide/sysctl/kernel.rst +++ b/Documentation/admin-guide/sysctl/kernel.rst @@ -591,6 +591,9 @@ if leaking kernel pointer values to unprivileged users is a concern. When ``kptr_restrict`` is set to 2, kernel pointers printed using %pK will be replaced with 0s regardless of privileges. +For disabling these security restrictions early at boot time (and once +for all), use the ``hash_pointers`` boot parameter instead. + softlockup_sys_info & hardlockup_sys_info ========================================= A comma separated list of extra system information to be dumped when -- 2.47.3