[PATCH 0/2] perf kvm: Fix memory leaks

[PATCH 0/2] perf kvm: Fix memory leaks

[Michalis Niarchos via B4 Relay]

Running ./perf kvm stat report with ASan, revealed some memory leaks:

==206006==ERROR: LeakSanitizer: detected memory leaks

Direct leak of 72 byte(s) in 3 object(s) allocated from:
    #0 0x7ff86bf2bea9 in calloc (/usr/lib/libasan.so.8+0x12bea9) (BuildId: 7f2845989b820f536270e19ec47df085ae89a675)
    #1 0x55f42795a0d5 in zalloc ../../lib/zalloc.c:8
    #2 0x55f42782d7f4 in per_vcpu_record /home/mike/git/linux/tools/perf/builtin-kvm.c:929
    #3 0x55f42782dab7 in handle_kvm_event /home/mike/git/linux/tools/perf/builtin-kvm.c:950
    #4 0x55f42782fa80 in process_sample_event /home/mike/git/linux/tools/perf/builtin-kvm.c:1159
    ...
    #14 0x55f42783236c in read_events /home/mike/git/linux/tools/perf/builtin-kvm.c:1591
    #15 0x55f4278326f8 in kvm_events_report_vcpu /home/mike/git/linux/tools/perf/builtin-kvm.c:1636

Direct leak of 8 byte(s) in 1 object(s) allocated from:
    #0 0x7ff86bf2c0c1 in malloc (/usr/lib/libasan.so.8+0x12c0c1) (BuildId: 7f2845989b820f536270e19ec47df085ae89a675)
    #1 0x55f427d78fe5 in thread__get util/thread.c:137
    #2 0x55f427c4f1fc in thread__find_map util/event.c:703
    #3 0x55f427c5001e in machine__resolve util/event.c:819
    #4 0x55f42782f84a in process_sample_event /home/mike/git/linux/tools/perf/builtin-kvm.c:1145
    ...
    #14 0x55f42783236c in read_events /home/mike/git/linux/tools/perf/builtin-kvm.c:1591
    #15 0x55f4278326f8 in kvm_events_report_vcpu /home/mike/git/linux/tools/perf/builtin-kvm.c:1636

Indirect leak of 256 byte(s) in 1 object(s) allocated from:
    #0 0x7ff86bf2bea9 in calloc (/usr/lib/libasan.so.8+0x12bea9) (BuildId: 7f2845989b820f536270e19ec47df085ae89a675)
    #1 0x55f42795a0d5 in zalloc ../../lib/zalloc.c:8
    #2 0x55f427d78857 in thread__new util/thread.c:46
    #3 0x55f427d7c083 in threads__findnew util/threads.c:116
    #4 0x55f427d2957c in __machine__findnew_thread util/machine.c:553
    #5 0x55f427d29734 in machine__findnew_thread util/machine.c:577
    #6 0x55f427d29a07 in machine__process_comm_event util/machine.c:616
    ...
    #16 0x55f42783236c in read_events /home/mike/git/linux/tools/perf/builtin-kvm.c:1591
    #17 0x55f4278326f8 in kvm_events_report_vcpu /home/mike/git/linux/tools/perf/builtin-kvm.c:1636

Indirect leak of 112 byte(s) in 1 object(s) allocated from:
    #0 0x7ff86bf2bea9 in calloc (/usr/lib/libasan.so.8+0x12bea9) (BuildId: 7f2845989b820f536270e19ec47df085ae89a675)
    #1 0x55f42795a0d5 in zalloc ../../lib/zalloc.c:8
    #2 0x55f427d40e37 in maps__new util/maps.c:270
    #3 0x55f427d78718 in thread__init_maps util/thread.c:30
    #4 0x55f427d295d8 in __machine__findnew_thread util/machine.c:563
    #5 0x55f427d29734 in machine__findnew_thread util/machine.c:577
    #6 0x55f427d29a07 in machine__process_comm_event util/machine.c:616
    ...
    #16 0x55f42783236c in read_events /home/mike/git/linux/tools/perf/builtin-kvm.c:1591
    #17 0x55f4278326f8 in kvm_events_report_vcpu /home/mike/git/linux/tools/perf/builtin-kvm.c:1636

Indirect leak of 48 byte(s) in 1 object(s) allocated from:
    #0 0x7ff86bf2bea9 in calloc (/usr/lib/libasan.so.8+0x12bea9) (BuildId: 7f2845989b820f536270e19ec47df085ae89a675)
    #1 0x55f42795a0d5 in zalloc ../../lib/zalloc.c:8
    #2 0x55f427d75f07 in comm__new util/comm.c:194
    #3 0x55f427d78a2f in thread__new util/thread.c:67
    #4 0x55f427d7c083 in threads__findnew util/threads.c:116
    #5 0x55f427d2957c in __machine__findnew_thread util/machine.c:553
    #6 0x55f427d29734 in machine__findnew_thread util/machine.c:577
    #7 0x55f427d29a07 in machine__process_comm_event util/machine.c:616
    ...
    #17 0x55f42783236c in read_events /home/mike/git/linux/tools/perf/builtin-kvm.c:1591
    #18 0x55f4278326f8 in kvm_events_report_vcpu /home/mike/git/linux/tools/perf/builtin-kvm.c:1636

Indirect leak of 32 byte(s) in 1 object(s) allocated from:
    #0 0x7ff86bf2bea9 in calloc (/usr/lib/libasan.so.8+0x12bea9) (BuildId: 7f2845989b820f536270e19ec47df085ae89a675)
    #1 0x55f427d731a1 in nsinfo__alloc util/namespaces.c:146
    #2 0x55f427d73275 in nsinfo__new util/namespaces.c:160
    #3 0x55f427d78ac9 in thread__new util/thread.c:74
    #4 0x55f427d7c083 in threads__findnew util/threads.c:116
    #5 0x55f427d2957c in __machine__findnew_thread util/machine.c:553
    #6 0x55f427d29734 in machine__findnew_thread util/machine.c:577
    #7 0x55f427d29a07 in machine__process_comm_event util/machine.c:616
    ...
    #18 0x55f4278326f8 in kvm_events_report_vcpu /home/mike/git/linux/tools/perf/builtin-kvm.c:1636
    #19 0x55f427833d77 in kvm_events_report /home/mike/git/linux/tools/perf/builtin-kvm.c:1764

Indirect leak of 24 byte(s) in 1 object(s) allocated from:
    #0 0x7ff86bf2bea9 in calloc (/usr/lib/libasan.so.8+0x12bea9) (BuildId: 7f2845989b820f536270e19ec47df085ae89a675)
    #1 0x55f42795a0d5 in zalloc ../../lib/zalloc.c:8
    #2 0x55f42782d7f4 in per_vcpu_record /home/mike/git/linux/tools/perf/builtin-kvm.c:929
    #3 0x55f42782dab7 in handle_kvm_event /home/mike/git/linux/tools/perf/builtin-kvm.c:950
    #4 0x55f42782fa80 in process_sample_event /home/mike/git/linux/tools/perf/builtin-kvm.c:1159
    ...
    #14 0x55f42783236c in read_events /home/mike/git/linux/tools/perf/builtin-kvm.c:1591
    #15 0x55f4278326f8 in kvm_events_report_vcpu /home/mike/git/linux/tools/perf/builtin-kvm.c:1636

Indirect leak of 8 byte(s) in 1 object(s) allocated from:
    #0 0x7ff86bf2c0c1 in malloc (/usr/lib/libasan.so.8+0x12c0c1) (BuildId: 7f2845989b820f536270e19ec47df085ae89a675)
    #1 0x55f427d7540f in comm_str__get util/comm.c:58
    #2 0x55f427d75ec5 in comm_strs__findnew util/comm.c:189
    #3 0x55f427d76056 in comm__override util/comm.c:215
    #4 0x55f427d796d1 in ____thread__set_comm util/thread.c:259
    #5 0x55f427d797c2 in __thread__set_comm util/thread.c:283
    #6 0x55f427d29b7a in machine__process_comm_event util/machine.c:629
    ...
    #16 0x55f42783236c in read_events /home/mike/git/linux/tools/perf/builtin-kvm.c:1591
    #17 0x55f4278326f8 in kvm_events_report_vcpu /home/mike/git/linux/tools/perf/builtin-kvm.c:1636

Indirect leak of 8 byte(s) in 1 object(s) allocated from:
    #0 0x7ff86bf2c0c1 in malloc (/usr/lib/libasan.so.8+0x12c0c1) (BuildId: 7f2845989b820f536270e19ec47df085ae89a675)
    #1 0x55f427d40f8d in maps__get util/maps.c:288
    #2 0x55f427d7875f in thread__init_maps util/thread.c:35
    #3 0x55f427d295d8 in __machine__findnew_thread util/machine.c:563
    #4 0x55f427d29734 in machine__findnew_thread util/machine.c:577
    #5 0x55f427d29a07 in machine__process_comm_event util/machine.c:616
    ...
    #15 0x55f42783236c in read_events /home/mike/git/linux/tools/perf/builtin-kvm.c:1591
    #16 0x55f4278326f8 in kvm_events_report_vcpu /home/mike/git/linux/tools/perf/builtin-kvm.c:1636

Indirect leak of 8 byte(s) in 1 object(s) allocated from:
    #0 0x7ff86bf2c0c1 in malloc (/usr/lib/libasan.so.8+0x12c0c1) (BuildId: 7f2845989b820f536270e19ec47df085ae89a675)
    #1 0x55f427d731b6 in nsinfo__alloc util/namespaces.c:147
    #2 0x55f427d73275 in nsinfo__new util/namespaces.c:160
    #3 0x55f427d78ac9 in thread__new util/thread.c:74
    #4 0x55f427d7c083 in threads__findnew util/threads.c:116
    #5 0x55f427d2957c in __machine__findnew_thread util/machine.c:553
    #6 0x55f427d29734 in machine__findnew_thread util/machine.c:577
    #7 0x55f427d29a07 in machine__process_comm_event util/machine.c:616
    ...
    #17 0x55f42783236c in read_events /home/mike/git/linux/tools/perf/builtin-kvm.c:1591
    #18 0x55f4278326f8 in kvm_events_report_vcpu /home/mike/git/linux/tools/perf/builtin-kvm.c:1636

SUMMARY: AddressSanitizer: 576 byte(s) leaked in 12 allocation(s).

Signed-off-by: Michalis Niarchos <michael.niarchos@gmail.com>
---
Michalis Niarchos (2):
      perf kvm: Fix memory leak in process_sample_event()
      perf kvm: Fix memory leak in cmd_kvm()

 tools/perf/builtin-kvm.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)
---
base-commit: 7c39d92d52c28686e7ae21eb726dc008fa1b2f0b
change-id: 20260807-perf-kvm-leaks-feca9044a3db

Best regards,
--  
Michalis Niarchos <michael.niarchos@gmail.com>

[PATCH 1/2] perf kvm: Fix memory leak in process_sample_event()

[Michalis Niarchos via B4 Relay]

From: Michalis Niarchos <michael.niarchos@gmail.com>

machine__resolve() indirectly acquires a thread reference via
machine__findnew_thread(). Release it, as suggested by the documentation
of the former.

Signed-off-by: Michalis Niarchos <michael.niarchos@gmail.com>
---
 tools/perf/builtin-kvm.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/tools/perf/builtin-kvm.c b/tools/perf/builtin-kvm.c
index 00baafb05603..8e7bc7b2db18 100644
--- a/tools/perf/builtin-kvm.c
+++ b/tools/perf/builtin-kvm.c
@@ -1145,7 +1145,7 @@ static int process_sample_event(const struct perf_tool *tool,
 	if (machine__resolve(machine, &kvm->al, sample) < 0) {
 		pr_warning("WARNING: at offset %#" PRIx64 ": fail to resolve address location, skipping sample\n",
 			   sample->file_offset);
-		return 0;
+		goto out;
 	}
 
 	thread = machine__findnew_thread(machine, sample->pid, sample->tid);
@@ -1153,13 +1153,16 @@ static int process_sample_event(const struct perf_tool *tool,
 		pr_debug("problem processing %s (%u) event at offset %#" PRIx64 ", skipping it.\n",
 			 perf_event__name(event->header.type), event->header.type,
 			 sample->file_offset);
-		return -1;
+		err = -1;
+		goto out;
 	}
 
 	if (!handle_kvm_event(kvm, thread, sample))
 		err = -1;
 
 	thread__put(thread);
+out:
+	addr_location__exit(&kvm->al);
 	return err;
 }
 

-- 
2.55.0

Re: [PATCH 1/2] perf kvm: Fix memory leak in process_sample_event()

[Namhyung Kim]

Hello,

On Fri, Aug 07, 2026 at 05:08:35PM +0200, Michalis Niarchos via B4 Relay wrote:
> From: Michalis Niarchos <michael.niarchos@gmail.com>
> 
> machine__resolve() indirectly acquires a thread reference via
> machine__findnew_thread(). Release it, as suggested by the documentation
> of the former.
> 
> Signed-off-by: Michalis Niarchos <michael.niarchos@gmail.com>
> ---
>  tools/perf/builtin-kvm.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/perf/builtin-kvm.c b/tools/perf/builtin-kvm.c
> index 00baafb05603..8e7bc7b2db18 100644
> --- a/tools/perf/builtin-kvm.c
> +++ b/tools/perf/builtin-kvm.c
> @@ -1145,7 +1145,7 @@ static int process_sample_event(const struct perf_tool *tool,
>  	if (machine__resolve(machine, &kvm->al, sample) < 0) {
>  		pr_warning("WARNING: at offset %#" PRIx64 ": fail to resolve address location, skipping sample\n",
>  			   sample->file_offset);
> -		return 0;
> +		goto out;

I think it's ok to return here when machine__resolve() returns -1.
I'll remove this hunk.

Thanks,
Namhyung


>  	}
>  
>  	thread = machine__findnew_thread(machine, sample->pid, sample->tid);
> @@ -1153,13 +1153,16 @@ static int process_sample_event(const struct perf_tool *tool,
>  		pr_debug("problem processing %s (%u) event at offset %#" PRIx64 ", skipping it.\n",
>  			 perf_event__name(event->header.type), event->header.type,
>  			 sample->file_offset);
> -		return -1;
> +		err = -1;
> +		goto out;
>  	}
>  
>  	if (!handle_kvm_event(kvm, thread, sample))
>  		err = -1;
>  
>  	thread__put(thread);
> +out:
> +	addr_location__exit(&kvm->al);
>  	return err;
>  }
>  
> 
> -- 
> 2.55.0
> 
> 

[PATCH 2/2] perf kvm: Fix memory leak in cmd_kvm()

[Michalis Niarchos via B4 Relay]

From: Michalis Niarchos <michael.niarchos@gmail.com>

Set the thread private data destructor.

Signed-off-by: Michalis Niarchos <michael.niarchos@gmail.com>
---
 tools/perf/builtin-kvm.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/tools/perf/builtin-kvm.c b/tools/perf/builtin-kvm.c
index 8e7bc7b2db18..21cb16b10f91 100644
--- a/tools/perf/builtin-kvm.c
+++ b/tools/perf/builtin-kvm.c
@@ -2149,6 +2149,8 @@ int cmd_kvm(int argc, const char **argv)
 	if (!argc)
 		usage_with_options(kvm_usage, kvm_options);
 
+	thread__set_priv_destructor(free);
+
 	if (!perf_host)
 		perf_guest = 1;
 

-- 
2.55.0