kernel/auditsc.c | 43 +++++++++++++++++++------------------------ 1 file changed, 19 insertions(+), 24 deletions(-)
Whenever there's audit context, __audit_inode_child() gets called
numerous times, which can lead to high latency in scenarios that
create too many sysfs/debugfs entries at once, for instance, upon
device_add_disk() invocation.
# uname -r
6.18.0-rc2+
# auditctl -a always,exit -F path=/tmp -k foo
# time insmod loop max_loop=1000
real 0m46.676s
user 0m0.000s
sys 0m46.405s
# perf record -a insmod loop max_loop=1000
# perf report --stdio |grep __audit_inode_child
32.73% insmod [kernel.kallsyms] [k] __audit_inode_child
__audit_inode_child() searches for both the parent and the child
in two different loops that iterate over the same list. This
process can be optimized by merging these into a single loop,
without changing the function behavior or affecting the code's
readability.
This patch merges the two loops that walk through the list
context->names_list into a single loop. This optimization resulted
in around 51% performance enhancement for the benchmark.
# uname -r
6.18.0-rc2-enhancedv3+
# auditctl -a always,exit -F path=/tmp -k foo
# time insmod loop max_loop=1000
real 0m22.899s
user 0m0.001s
sys 0m22.652s
Signed-off-by: Ricardo Robaina <rrobaina@redhat.com>
---
kernel/auditsc.c | 43 +++++++++++++++++++------------------------
1 file changed, 19 insertions(+), 24 deletions(-)
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index d1966144bdfe..dd0563a8e0be 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -2416,41 +2416,36 @@ void __audit_inode_child(struct inode *parent,
if (inode)
handle_one(inode);
- /* look for a parent entry first */
list_for_each_entry(n, &context->names_list, list) {
- if (!n->name ||
- (n->type != AUDIT_TYPE_PARENT &&
- n->type != AUDIT_TYPE_UNKNOWN))
+ /* can only match entries that have a name */
+ if (!n->name)
continue;
- if (n->ino == parent->i_ino && n->dev == parent->i_sb->s_dev &&
- !audit_compare_dname_path(dname,
- n->name->name, n->name_len)) {
- if (n->type == AUDIT_TYPE_UNKNOWN)
- n->type = AUDIT_TYPE_PARENT;
+ /* look for a parent entry first */
+ if (!found_parent &&
+ (n->type == AUDIT_TYPE_PARENT || n->type == AUDIT_TYPE_UNKNOWN) &&
+ (n->ino == parent->i_ino && n->dev == parent->i_sb->s_dev &&
+ !audit_compare_dname_path(dname, n->name->name, n->name_len))) {
+ n->type = AUDIT_TYPE_PARENT;
found_parent = n;
- break;
- }
- }
-
- cond_resched();
-
- /* is there a matching child entry? */
- list_for_each_entry(n, &context->names_list, list) {
- /* can only match entries that have a name */
- if (!n->name ||
- (n->type != type && n->type != AUDIT_TYPE_UNKNOWN))
+ if (found_child)
+ break;
continue;
+ }
- if (!strcmp(dname->name, n->name->name) ||
- !audit_compare_dname_path(dname, n->name->name,
+ /* is there a matching child entry? */
+ if (!found_child &&
+ (n->type == type || n->type == AUDIT_TYPE_UNKNOWN) &&
+ (!strcmp(dname->name, n->name->name) ||
+ !audit_compare_dname_path(dname, n->name->name,
found_parent ?
found_parent->name_len :
- AUDIT_NAME_FULL)) {
+ AUDIT_NAME_FULL))) {
if (n->type == AUDIT_TYPE_UNKNOWN)
n->type = type;
found_child = n;
- break;
+ if (found_parent)
+ break;
}
}
--
2.51.0On Oct 31, 2025 Ricardo Robaina <rrobaina@redhat.com> wrote: > > Whenever there's audit context, __audit_inode_child() gets called > numerous times, which can lead to high latency in scenarios that > create too many sysfs/debugfs entries at once, for instance, upon > device_add_disk() invocation. > > # uname -r > 6.18.0-rc2+ > > # auditctl -a always,exit -F path=/tmp -k foo > # time insmod loop max_loop=1000 > real 0m46.676s > user 0m0.000s > sys 0m46.405s > > # perf record -a insmod loop max_loop=1000 > # perf report --stdio |grep __audit_inode_child > 32.73% insmod [kernel.kallsyms] [k] __audit_inode_child > > __audit_inode_child() searches for both the parent and the child > in two different loops that iterate over the same list. This > process can be optimized by merging these into a single loop, > without changing the function behavior or affecting the code's > readability. > > This patch merges the two loops that walk through the list > context->names_list into a single loop. This optimization resulted > in around 51% performance enhancement for the benchmark. > > # uname -r > 6.18.0-rc2-enhancedv3+ > > # auditctl -a always,exit -F path=/tmp -k foo > # time insmod loop max_loop=1000 > real 0m22.899s > user 0m0.001s > sys 0m22.652s > > Signed-off-by: Ricardo Robaina <rrobaina@redhat.com> > --- > kernel/auditsc.c | 43 +++++++++++++++++++------------------------ > 1 file changed, 19 insertions(+), 24 deletions(-) Looks good to me, merged into audit/dev, thanks! -- paul-moore.com
Thanks, Paul! On Fri, Nov 7, 2025 at 6:50 PM Paul Moore <paul@paul-moore.com> wrote: > > On Oct 31, 2025 Ricardo Robaina <rrobaina@redhat.com> wrote: > > > > Whenever there's audit context, __audit_inode_child() gets called > > numerous times, which can lead to high latency in scenarios that > > create too many sysfs/debugfs entries at once, for instance, upon > > device_add_disk() invocation. > > > > # uname -r > > 6.18.0-rc2+ > > > > # auditctl -a always,exit -F path=/tmp -k foo > > # time insmod loop max_loop=1000 > > real 0m46.676s > > user 0m0.000s > > sys 0m46.405s > > > > # perf record -a insmod loop max_loop=1000 > > # perf report --stdio |grep __audit_inode_child > > 32.73% insmod [kernel.kallsyms] [k] __audit_inode_child > > > > __audit_inode_child() searches for both the parent and the child > > in two different loops that iterate over the same list. This > > process can be optimized by merging these into a single loop, > > without changing the function behavior or affecting the code's > > readability. > > > > This patch merges the two loops that walk through the list > > context->names_list into a single loop. This optimization resulted > > in around 51% performance enhancement for the benchmark. > > > > # uname -r > > 6.18.0-rc2-enhancedv3+ > > > > # auditctl -a always,exit -F path=/tmp -k foo > > # time insmod loop max_loop=1000 > > real 0m22.899s > > user 0m0.001s > > sys 0m22.652s > > > > Signed-off-by: Ricardo Robaina <rrobaina@redhat.com> > > --- > > kernel/auditsc.c | 43 +++++++++++++++++++------------------------ > > 1 file changed, 19 insertions(+), 24 deletions(-) > > Looks good to me, merged into audit/dev, thanks! > > -- > paul-moore.com >
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