* [for-next][PATCH 1/3] tracing: Add traceoff_after_boot option
2025-02-27 0:12 [for-next][PATCH 0/3] tracing: Updates for v6.15 Steven Rostedt
@ 2025-02-27 0:12 ` Steven Rostedt
2025-02-27 0:12 ` [for-next][PATCH 2/3] mm/memblock: Add reserved memory release function Steven Rostedt
` (2 subsequent siblings)
3 siblings, 0 replies; 6+ messages in thread
From: Steven Rostedt @ 2025-02-27 0:12 UTC (permalink / raw)
To: linux-kernel
Cc: Masami Hiramatsu, Mark Rutland, Mathieu Desnoyers, Andrew Morton,
Borislav Petkov
From: Steven Rostedt <rostedt@goodmis.org>
Sometimes tracing is used to debug issues during the boot process. Since
the trace buffer has a limited amount of storage, it may be prudent to
disable tracing after the boot is finished, otherwise the critical
information may be overwritten. With this option, the main tracing buffer
will be turned off at the end of the boot process.
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Borislav Petkov <bp@alien8.de>
Link: https://lore.kernel.org/20250208103017.48a7ec83@batman.local.home
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
Documentation/admin-guide/kernel-parameters.txt | 9 +++++++++
kernel/trace/trace.c | 11 +++++++++++
2 files changed, 20 insertions(+)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index fb8752b42ec8..e8ca4eabd152 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -7279,6 +7279,15 @@
See also "Event triggers" in Documentation/trace/events.rst
+ traceoff_after_boot
+ [FTRACE] Sometimes tracing is used to debug issues
+ during the boot process. Since the trace buffer has a
+ limited amount of storage, it may be prudent to
+ disable tracing after the boot is finished, otherwise
+ the critical information may be overwritten. With this
+ option, the main tracing buffer will be turned off at
+ the end of the boot process.
+
traceoff_on_warning
[FTRACE] enable this option to disable tracing when a
warning is hit. This turns off "tracing_on". Tracing can
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 0e6d517e74e0..61458d8c3a61 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -87,6 +87,7 @@ void __init disable_tracing_selftest(const char *reason)
static struct trace_iterator *tracepoint_print_iter;
int tracepoint_printk;
static bool tracepoint_printk_stop_on_boot __initdata;
+static bool traceoff_after_boot __initdata;
static DEFINE_STATIC_KEY_FALSE(tracepoint_printk_key);
/* For tracers that don't implement custom flags */
@@ -330,6 +331,13 @@ static int __init set_tracepoint_printk_stop(char *str)
}
__setup("tp_printk_stop_on_boot", set_tracepoint_printk_stop);
+static int __init set_traceoff_after_boot(char *str)
+{
+ traceoff_after_boot = true;
+ return 1;
+}
+__setup("traceoff_after_boot", set_traceoff_after_boot);
+
unsigned long long ns2usecs(u64 nsec)
{
nsec += 500;
@@ -10704,6 +10712,9 @@ __init static int late_trace_init(void)
tracepoint_printk = 0;
}
+ if (traceoff_after_boot)
+ tracing_off();
+
tracing_set_default_clock();
clear_boot_tracer();
return 0;
--
2.47.2
^ permalink raw reply [flat|nested] 6+ messages in thread* [for-next][PATCH 2/3] mm/memblock: Add reserved memory release function
2025-02-27 0:12 [for-next][PATCH 0/3] tracing: Updates for v6.15 Steven Rostedt
2025-02-27 0:12 ` [for-next][PATCH 1/3] tracing: Add traceoff_after_boot option Steven Rostedt
@ 2025-02-27 0:12 ` Steven Rostedt
2025-02-27 0:12 ` [for-next][PATCH 3/3] tracing: Freeable reserved ring buffer Steven Rostedt
2025-03-06 18:26 ` [for-next][PATCH 0/3] tracing: Updates for v6.15 Steven Rostedt
3 siblings, 0 replies; 6+ messages in thread
From: Steven Rostedt @ 2025-02-27 0:12 UTC (permalink / raw)
To: linux-kernel
Cc: Masami Hiramatsu, Mark Rutland, Mathieu Desnoyers, Andrew Morton,
Mike Rapoport (Microsoft),
linux-mm
From: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Add reserve_mem_release_by_name() to release a reserved memory region
with a given name. This allows us to release reserved memory which is
defined by kernel cmdline, after boot.
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: linux-mm@kvack.org
Link: https://lore.kernel.org/173989133862.230693.14094993331347437600.stgit@devnote2
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
include/linux/mm.h | 1 +
mm/memblock.c | 66 +++++++++++++++++++++++++++++++++++++---------
2 files changed, 55 insertions(+), 12 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 7b1068ddcbb7..1ee9e7447485 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -4123,6 +4123,7 @@ void vma_pgtable_walk_begin(struct vm_area_struct *vma);
void vma_pgtable_walk_end(struct vm_area_struct *vma);
int reserve_mem_find_by_name(const char *name, phys_addr_t *start, phys_addr_t *size);
+int reserve_mem_release_by_name(const char *name);
#ifdef CONFIG_64BIT
int do_mseal(unsigned long start, size_t len_in, unsigned long flags);
diff --git a/mm/memblock.c b/mm/memblock.c
index 95af35fd1389..8cd95f60015d 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -16,6 +16,7 @@
#include <linux/kmemleak.h>
#include <linux/seq_file.h>
#include <linux/memblock.h>
+#include <linux/mutex.h>
#include <asm/sections.h>
#include <linux/io.h>
@@ -2283,6 +2284,7 @@ struct reserve_mem_table {
};
static struct reserve_mem_table reserved_mem_table[RESERVE_MEM_MAX_ENTRIES];
static int reserved_mem_count;
+static DEFINE_MUTEX(reserve_mem_lock);
/* Add wildcard region with a lookup name */
static void __init reserved_mem_add(phys_addr_t start, phys_addr_t size,
@@ -2296,6 +2298,21 @@ static void __init reserved_mem_add(phys_addr_t start, phys_addr_t size,
strscpy(map->name, name);
}
+static struct reserve_mem_table *reserve_mem_find_by_name_nolock(const char *name)
+{
+ struct reserve_mem_table *map;
+ int i;
+
+ for (i = 0; i < reserved_mem_count; i++) {
+ map = &reserved_mem_table[i];
+ if (!map->size)
+ continue;
+ if (strcmp(name, map->name) == 0)
+ return map;
+ }
+ return NULL;
+}
+
/**
* reserve_mem_find_by_name - Find reserved memory region with a given name
* @name: The name that is attached to a reserved memory region
@@ -2309,22 +2326,47 @@ static void __init reserved_mem_add(phys_addr_t start, phys_addr_t size,
int reserve_mem_find_by_name(const char *name, phys_addr_t *start, phys_addr_t *size)
{
struct reserve_mem_table *map;
- int i;
- for (i = 0; i < reserved_mem_count; i++) {
- map = &reserved_mem_table[i];
- if (!map->size)
- continue;
- if (strcmp(name, map->name) == 0) {
- *start = map->start;
- *size = map->size;
- return 1;
- }
- }
- return 0;
+ guard(mutex)(&reserve_mem_lock);
+ map = reserve_mem_find_by_name_nolock(name);
+ if (!map)
+ return 0;
+
+ *start = map->start;
+ *size = map->size;
+ return 1;
}
EXPORT_SYMBOL_GPL(reserve_mem_find_by_name);
+/**
+ * reserve_mem_release_by_name - Release reserved memory region with a given name
+ * @name: The name that is attatched to a reserved memory region
+ *
+ * Forcibly release the pages in the reserved memory region so that those memory
+ * can be used as free memory. After released the reserved region size becomes 0.
+ *
+ * Returns: 1 if released or 0 if not found.
+ */
+int reserve_mem_release_by_name(const char *name)
+{
+ char buf[RESERVE_MEM_NAME_SIZE + 12];
+ struct reserve_mem_table *map;
+ void *start, *end;
+
+ guard(mutex)(&reserve_mem_lock);
+ map = reserve_mem_find_by_name_nolock(name);
+ if (!map)
+ return 0;
+
+ start = phys_to_virt(map->start);
+ end = start + map->size - 1;
+ snprintf(buf, sizeof(buf), "reserve_mem:%s", name);
+ free_reserved_area(start, end, 0, buf);
+ map->size = 0;
+
+ return 1;
+}
+
/*
* Parse reserve_mem=nn:align:name
*/
--
2.47.2
^ permalink raw reply [flat|nested] 6+ messages in thread* [for-next][PATCH 3/3] tracing: Freeable reserved ring buffer
2025-02-27 0:12 [for-next][PATCH 0/3] tracing: Updates for v6.15 Steven Rostedt
2025-02-27 0:12 ` [for-next][PATCH 1/3] tracing: Add traceoff_after_boot option Steven Rostedt
2025-02-27 0:12 ` [for-next][PATCH 2/3] mm/memblock: Add reserved memory release function Steven Rostedt
@ 2025-02-27 0:12 ` Steven Rostedt
2025-03-06 18:26 ` [for-next][PATCH 0/3] tracing: Updates for v6.15 Steven Rostedt
3 siblings, 0 replies; 6+ messages in thread
From: Steven Rostedt @ 2025-02-27 0:12 UTC (permalink / raw)
To: linux-kernel
Cc: Masami Hiramatsu, Mark Rutland, Mathieu Desnoyers, Andrew Morton,
Mike Rapoport
From: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Make the ring buffer on reserved memory to be freeable. This allows us
to free the trace instance on the reserved memory without changing
cmdline and rebooting. Even if we can not change the kernel cmdline
for security reason, we can release the reserved memory for the ring
buffer as free (available) memory.
For example, boot kernel with reserved memory;
"reserve_mem=20M:2M:trace trace_instance=boot_mapped^traceoff@trace"
~ # free
total used free shared buff/cache available
Mem: 1995548 50544 1927568 14964 17436 1911480
Swap: 0 0 0
~ # rmdir /sys/kernel/tracing/instances/boot_mapped/
[ 23.704023] Freeing reserve_mem:trace memory: 20476K
~ # free
total used free shared buff/cache available
Mem: 2016024 41844 1956740 14968 17440 1940572
Swap: 0 0 0
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Mike Rapoport <rppt@kernel.org>
Link: https://lore.kernel.org/173989134814.230693.18199312930337815629.stgit@devnote2
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
kernel/trace/trace.c | 13 ++++++++++++-
kernel/trace/trace.h | 1 +
2 files changed, 13 insertions(+), 1 deletion(-)
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 61458d8c3a61..b4bcb85094d9 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -9292,6 +9292,9 @@ static void free_trace_buffers(struct trace_array *tr)
#ifdef CONFIG_TRACER_MAX_TRACE
free_trace_buffer(&tr->max_buffer);
#endif
+
+ if (tr->range_addr_start)
+ vunmap((void *)tr->range_addr_start);
}
static void init_trace_flags_index(struct trace_array *tr)
@@ -9453,6 +9456,7 @@ trace_array_create_systems(const char *name, const char *systems,
free_cpumask_var(tr->pipe_cpumask);
free_cpumask_var(tr->tracing_cpumask);
kfree_const(tr->system_names);
+ kfree(tr->range_name);
kfree(tr->name);
kfree(tr);
@@ -9579,6 +9583,11 @@ static int __remove_instance(struct trace_array *tr)
free_trace_buffers(tr);
clear_tracing_err_log(tr);
+ if (tr->range_name) {
+ reserve_mem_release_by_name(tr->range_name);
+ kfree(tr->range_name);
+ }
+
for (i = 0; i < tr->nr_topts; i++) {
kfree(tr->topts[i].topts);
}
@@ -10376,6 +10385,7 @@ __init static void enable_instances(void)
bool traceoff = false;
char *flag_delim;
char *addr_delim;
+ char *rname __free(kfree) = NULL;
tok = strsep(&curr_str, ",");
@@ -10432,6 +10442,7 @@ __init static void enable_instances(void)
pr_warn("Failed to map boot instance %s to %s\n", name, tok);
continue;
}
+ rname = kstrdup(tok, GFP_KERNEL);
}
if (start) {
@@ -10468,7 +10479,7 @@ __init static void enable_instances(void)
*/
if (start) {
tr->flags |= TRACE_ARRAY_FL_BOOT;
- tr->ref++;
+ tr->range_name = no_free_ptr(rname);
}
while ((tok = strsep(&curr_str, ","))) {
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 9c21ba45b7af..93b6279d3da4 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -348,6 +348,7 @@ struct trace_array {
unsigned int mapped;
unsigned long range_addr_start;
unsigned long range_addr_size;
+ char *range_name;
long text_delta;
long data_delta;
--
2.47.2
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [for-next][PATCH 0/3] tracing: Updates for v6.15
2025-02-27 0:12 [for-next][PATCH 0/3] tracing: Updates for v6.15 Steven Rostedt
` (2 preceding siblings ...)
2025-02-27 0:12 ` [for-next][PATCH 3/3] tracing: Freeable reserved ring buffer Steven Rostedt
@ 2025-03-06 18:26 ` Steven Rostedt
3 siblings, 0 replies; 6+ messages in thread
From: Steven Rostedt @ 2025-03-06 18:26 UTC (permalink / raw)
To: linux-kernel
Cc: Masami Hiramatsu, Mark Rutland, Mathieu Desnoyers, Andrew Morton
On Wed, 26 Feb 2025 19:12:35 -0500
Steven Rostedt <rostedt@goodmis.org> wrote:
> Masami Hiramatsu (Google) (2):
> mm/memblock: Add reserved memory release function
> tracing: Freeable reserved ring buffer
Masami,
I'm going to revert these two patches from the trace/for-next tree and
rebase them on top of the ring-buffer/for-next, as they conflict, and I
rather not send Linus a pull request that has conflicts between two of my
topic branches.
-- Steve
^ permalink raw reply [flat|nested] 6+ messages in thread