mirrors/linux-stable
1
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git synced 2024-09-29 13:53:33 +00:00
Code Issues Releases Wiki Activity

lib: introduce early boot parameter to avoid page_ext memory overhead

Browse source 
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>
This commit is contained in:
Suren Baghdasaryan 2024-03-21 09:36:37 -07:00 committed by Andrew Morton
parent dcfe378c81
commit 8d469d0bee
1 changed files with 40 additions and 1 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

41
lib/alloc_tag.c
View file

@ -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();