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Message-ID: <20230110130121.1279-1-thunder.leizhen@huawei.com>
Date: Tue, 10 Jan 2023 21:01:21 +0800
From: Zhen Lei <thunder.leizhen@...wei.com>
To: Josh Poimboeuf <jpoimboe@...nel.org>,
Jiri Kosina <jikos@...nel.org>,
Miroslav Benes <mbenes@...e.cz>,
Petr Mladek <pmladek@...e.com>,
Joe Lawrence <joe.lawrence@...hat.com>,
Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>,
Andrii Nakryiko <andrii@...nel.org>,
Martin KaFai Lau <martin.lau@...ux.dev>,
Song Liu <song@...nel.org>, Yonghong Song <yhs@...com>,
John Fastabend <john.fastabend@...il.com>,
KP Singh <kpsingh@...nel.org>,
Stanislav Fomichev <sdf@...gle.com>,
Hao Luo <haoluo@...gle.com>, Jiri Olsa <jolsa@...nel.org>,
Steven Rostedt <rostedt@...dmis.org>,
Masami Hiramatsu <mhiramat@...nel.org>,
Mark Rutland <mark.rutland@....com>, <bpf@...r.kernel.org>,
<linux-trace-kernel@...r.kernel.org>,
<live-patching@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
Luis Chamberlain <mcgrof@...nel.org>,
<linux-modules@...r.kernel.org>
CC: Zhen Lei <thunder.leizhen@...wei.com>
Subject: [PATCH v3] kallsyms: Remove the performance test from kallsyms_selftest.c
[T58] BUG: sleeping function called from invalid context at kernel/kallsyms.c:305
[T58] in_atomic(): 0, irqs_disabled(): 128, non_block: 0, pid: 58, name: kallsyms_test
[T58] preempt_count: 0, expected: 0
[T58] RCU nest depth: 0, expected: 0
[T58] no locks held by kallsyms_test/58.
[T58] irq event stamp: 18899904
[T58] hardirqs last enabled at (18899903): finish_task_switch.isra.0 (core.c:?)
[T58] hardirqs last disabled at (18899904): test_perf_kallsyms_on_each_symbol (kallsyms_selftest.c:?)
[T58] softirqs last enabled at (18899886): __do_softirq (??:?)
[T58] softirqs last disabled at (18899879): ____do_softirq (irq.c:?)
[T58] CPU: 0 PID: 58 Comm: kallsyms_test Tainted: G T 6.1.0-next-20221215 #2
[T58] Hardware name: linux,dummy-virt (DT)
[T58] Call trace:
[T58] dump_backtrace (??:?)
[T58] show_stack (??:?)
[T58] dump_stack_lvl (??:?)
[T58] dump_stack (??:?)
[T58] __might_resched (??:?)
[T58] kallsyms_on_each_symbol (??:?)
[T58] test_perf_kallsyms_on_each_symbol (kallsyms_selftest.c:?)
[T58] test_entry (kallsyms_selftest.c:?)
[T58] kthread (kthread.c:?)
[T58] ret_from_fork (??:?)
[T58] kallsyms_selftest: kallsyms_on_each_symbol() traverse all: 5744310840 ns
[T58] kallsyms_selftest: kallsyms_on_each_match_symbol() traverse all: 1164580 ns
[T58] kallsyms_selftest: finish
Functions kallsyms_on_each_symbol() and kallsyms_on_each_match_symbol()
call the user-registered hook function for each symbol that meets the
requirements. Because it is uncertain how long that hook function will
execute, they call cond_resched() to avoid consuming CPU resources for a
long time. Therefore, they cannot be called with irqs disabled.
Given that people don't care about the performance of kallsyms, let's
simply remove it.
Fixes: 30f3bb09778d ("kallsyms: Add self-test facility")
Reported-by: Anders Roxell <anders.roxell@...aro.org>
Suggested-by: Petr Mladek <pmladek@...e.com>
Signed-off-by: Zhen Lei <thunder.leizhen@...wei.com>
---
kernel/kallsyms_selftest.c | 88 +-------------------------------------
1 file changed, 1 insertion(+), 87 deletions(-)
v1 --> v2:
1. Keep calling cond_resched() when CONFIG_KALLSYMS_SELFTEST=y. Instead,
function kallsyms_on_each_match_symbol() and kallsyms_on_each_symbol()
are not protected by local_irq_save() in kallsyms_selftest.c.
v2 --> v3:
1. Remove the performance test functions.
[v2] https://lkml.org/lkml/2022/12/27/762
diff --git a/kernel/kallsyms_selftest.c b/kernel/kallsyms_selftest.c
index f35d9cc1aab1544..79c42d80b8f69a1 100644
--- a/kernel/kallsyms_selftest.c
+++ b/kernel/kallsyms_selftest.c
@@ -12,9 +12,9 @@
#include <linux/init.h>
#include <linux/module.h>
#include <linux/kallsyms.h>
+#include <linux/kthread.h>
#include <linux/random.h>
#include <linux/sched/clock.h>
-#include <linux/kthread.h>
#include <linux/vmalloc.h>
#include "kallsyms_internal.h"
@@ -93,7 +93,6 @@ static struct test_item test_items[] = {
#endif
};
-static char stub_name[KSYM_NAME_LEN];
static int stat_symbol_len(void *data, const char *name, struct module *mod, unsigned long addr)
{
@@ -109,16 +108,6 @@ static void test_kallsyms_compression_ratio(void)
kallsyms_on_each_symbol(stat_symbol_len, &total_len);
- /*
- * A symbol name cannot start with a number. This stub name helps us
- * traverse the entire symbol table without finding a match. It's used
- * for subsequent performance tests, and its length is the average
- * length of all symbol names.
- */
- memset(stub_name, '4', sizeof(stub_name));
- pos = total_len / kallsyms_num_syms;
- stub_name[pos] = 0;
-
pos = 0;
num = 0;
off = 0;
@@ -154,43 +143,6 @@ static void test_kallsyms_compression_ratio(void)
pr_info(" ---------------------------------------------------------\n");
}
-static int lookup_name(void *data, const char *name, struct module *mod, unsigned long addr)
-{
- u64 t0, t1, t;
- unsigned long flags;
- struct test_stat *stat = (struct test_stat *)data;
-
- local_irq_save(flags);
- t0 = sched_clock();
- (void)kallsyms_lookup_name(name);
- t1 = sched_clock();
- local_irq_restore(flags);
-
- t = t1 - t0;
- if (t < stat->min)
- stat->min = t;
-
- if (t > stat->max)
- stat->max = t;
-
- stat->real_cnt++;
- stat->sum += t;
-
- return 0;
-}
-
-static void test_perf_kallsyms_lookup_name(void)
-{
- struct test_stat stat;
-
- memset(&stat, 0, sizeof(stat));
- stat.min = INT_MAX;
- kallsyms_on_each_symbol(lookup_name, &stat);
- pr_info("kallsyms_lookup_name() looked up %d symbols\n", stat.real_cnt);
- pr_info("The time spent on each symbol is (ns): min=%d, max=%d, avg=%lld\n",
- stat.min, stat.max, div_u64(stat.sum, stat.real_cnt));
-}
-
static bool match_cleanup_name(const char *s, const char *name)
{
char *p;
@@ -231,24 +183,6 @@ static int find_symbol(void *data, const char *name, struct module *mod, unsigne
return 0;
}
-static void test_perf_kallsyms_on_each_symbol(void)
-{
- u64 t0, t1;
- unsigned long flags;
- struct test_stat stat;
-
- memset(&stat, 0, sizeof(stat));
- stat.max = INT_MAX;
- stat.name = stub_name;
- stat.perf = 1;
- local_irq_save(flags);
- t0 = sched_clock();
- kallsyms_on_each_symbol(find_symbol, &stat);
- t1 = sched_clock();
- local_irq_restore(flags);
- pr_info("kallsyms_on_each_symbol() traverse all: %lld ns\n", t1 - t0);
-}
-
static int match_symbol(void *data, unsigned long addr)
{
struct test_stat *stat = (struct test_stat *)data;
@@ -267,23 +201,6 @@ static int match_symbol(void *data, unsigned long addr)
return 0;
}
-static void test_perf_kallsyms_on_each_match_symbol(void)
-{
- u64 t0, t1;
- unsigned long flags;
- struct test_stat stat;
-
- memset(&stat, 0, sizeof(stat));
- stat.max = INT_MAX;
- stat.name = stub_name;
- local_irq_save(flags);
- t0 = sched_clock();
- kallsyms_on_each_match_symbol(match_symbol, stat.name, &stat);
- t1 = sched_clock();
- local_irq_restore(flags);
- pr_info("kallsyms_on_each_match_symbol() traverse all: %lld ns\n", t1 - t0);
-}
-
static int test_kallsyms_basic_function(void)
{
int i, j, ret;
@@ -460,9 +377,6 @@ static int test_entry(void *p)
}
test_kallsyms_compression_ratio();
- test_perf_kallsyms_lookup_name();
- test_perf_kallsyms_on_each_symbol();
- test_perf_kallsyms_on_each_match_symbol();
pr_info("finish\n");
return 0;
--
2.25.1
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