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author | Suren Baghdasaryan <surenb@google.com> | 2024-03-21 17:36:37 +0100 |
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committer | Andrew Morton <akpm@linux-foundation.org> | 2024-04-26 05:55:53 +0200 |
commit | 8d469d0bee74d3f2d02f0b232933a3f084d9cbf7 (patch) | |
tree | a2d56c1c54b96f47f48ee35bb74c528a50d162ab /lib | |
parent | lib: introduce support for page allocation tagging (diff) | |
download | linux-8d469d0bee74d3f2d02f0b232933a3f084d9cbf7.tar.xz linux-8d469d0bee74d3f2d02f0b232933a3f084d9cbf7.zip |
lib: introduce early boot parameter to avoid page_ext memory overhead
The highest memory overhead from memory allocation profiling comes from
page_ext objects. This overhead exists even if the feature is disabled
but compiled-in. To avoid it, introduce an early boot parameter that
prevents page_ext object creation. The new boot parameter is a tri-state
with possible values of 0|1|never. When it is set to "never" the memory
allocation profiling support is disabled, and overhead is minimized
(currently no page_ext objects are allocated, in the future more overhead
might be eliminated). As a result we also lose ability to enable memory
allocation profiling at runtime (because there is no space to store
alloctag references). Runtime sysctrl becomes read-only if the early boot
parameter was set to "never". Note that the default value of this boot
parameter depends on the CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT
configuration. When CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT=n the
boot parameter is set to "never", therefore eliminating any overhead.
CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT=y results in boot parameter
being set to 1 (enabled). This allows distributions to avoid any overhead
by setting CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT=n config and with
no changes to the kernel command line.
We reuse sysctl.vm.mem_profiling boot parameter name in order to avoid
introducing yet another control. This change turns it into a tri-state
early boot parameter.
Link: https://lkml.kernel.org/r/20240321163705.3067592-16-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Tested-by: Kees Cook <keescook@chromium.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Alex Gaynor <alex.gaynor@gmail.com>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Andreas Hindborg <a.hindborg@samsung.com>
Cc: Benno Lossin <benno.lossin@proton.me>
Cc: "Björn Roy Baron" <bjorn3_gh@protonmail.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Gary Guo <gary@garyguo.net>
Cc: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Wedson Almeida Filho <wedsonaf@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'lib')
-rw-r--r-- | lib/alloc_tag.c | 41 |
1 files changed, 40 insertions, 1 deletions
diff --git a/lib/alloc_tag.c b/lib/alloc_tag.c index 59bb71036837..6bd8e85beaf7 100644 --- a/lib/alloc_tag.c +++ b/lib/alloc_tag.c @@ -119,9 +119,46 @@ static bool alloc_tag_module_unload(struct codetag_type *cttype, return module_unused; } +#ifdef CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT +static bool mem_profiling_support __meminitdata = true; +#else +static bool mem_profiling_support __meminitdata; +#endif + +static int __init setup_early_mem_profiling(char *str) +{ + bool enable; + + if (!str || !str[0]) + return -EINVAL; + + if (!strncmp(str, "never", 5)) { + enable = false; + mem_profiling_support = false; + } else { + int res; + + res = kstrtobool(str, &enable); + if (res) + return res; + + mem_profiling_support = true; + } + + if (enable != static_key_enabled(&mem_alloc_profiling_key)) { + if (enable) + static_branch_enable(&mem_alloc_profiling_key); + else + static_branch_disable(&mem_alloc_profiling_key); + } + + return 0; +} +early_param("sysctl.vm.mem_profiling", setup_early_mem_profiling); + static __init bool need_page_alloc_tagging(void) { - return true; + return mem_profiling_support; } static __init void init_page_alloc_tagging(void) @@ -161,6 +198,8 @@ static int __init alloc_tag_init(void) if (IS_ERR(alloc_tag_cttype)) return PTR_ERR(alloc_tag_cttype); + if (!mem_profiling_support) + memory_allocation_profiling_sysctls[0].mode = 0444; register_sysctl_init("vm", memory_allocation_profiling_sysctls); procfs_init(); |