Patch "perf sched: Avoid large stack allocations" has been added to the 6.1-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    perf sched: Avoid large stack allocations

to the 6.1-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     perf-sched-avoid-large-stack-allocations.patch
and it can be found in the queue-6.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 07a990a72b237bdb33aad1562d8d24301808dd03
Author: Ian Rogers <irogers@xxxxxxxxxx>
Date:   Fri May 26 20:43:19 2023 -0700

    perf sched: Avoid large stack allocations
    
    [ Upstream commit 232418a0b2e8b8e72dac003b19352f1b647cdb31 ]
    
    Commit 5ded57ac1bdb ("perf inject: Remove static variables") moved
    static variables to local, however, in this case 3 MAX_CPUS (4096)
    sized arrays were moved onto the stack making the stack frame quite
    large. Avoid the stack usage by dynamically allocating the arrays.
    
    Signed-off-by: Ian Rogers <irogers@xxxxxxxxxx>
    Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
    Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
    Cc: Ingo Molnar <mingo@xxxxxxxxxx>
    Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
    Cc: Mark Rutland <mark.rutland@xxxxxxx>
    Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
    Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
    Link: https://lore.kernel.org/r/20230527034324.2597593-2-irogers@xxxxxxxxxx
    Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
    Stable-dep-of: 1a5efc9e13f3 ("libsubcmd: Don't free the usage string")
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c
index d83a7569db0e2..3eff78e7b67a2 100644
--- a/tools/perf/builtin-sched.c
+++ b/tools/perf/builtin-sched.c
@@ -193,8 +193,8 @@ struct perf_sched {
  * weird events, such as a task being switched away that is not current.
  */
 	struct perf_cpu	 max_cpu;
-	u32		 curr_pid[MAX_CPUS];
-	struct thread	 *curr_thread[MAX_CPUS];
+	u32		 *curr_pid;
+	struct thread	 **curr_thread;
 	char		 next_shortname1;
 	char		 next_shortname2;
 	unsigned int	 replay_repeat;
@@ -224,7 +224,7 @@ struct perf_sched {
 	u64		 run_avg;
 	u64		 all_runtime;
 	u64		 all_count;
-	u64		 cpu_last_switched[MAX_CPUS];
+	u64		 *cpu_last_switched;
 	struct rb_root_cached atom_root, sorted_atom_root, merged_atom_root;
 	struct list_head sort_list, cmp_pid;
 	bool force;
@@ -3590,7 +3590,22 @@ int cmd_sched(int argc, const char **argv)
 
 	mutex_init(&sched.start_work_mutex);
 	mutex_init(&sched.work_done_wait_mutex);
-	for (i = 0; i < ARRAY_SIZE(sched.curr_pid); i++)
+	sched.curr_thread = calloc(MAX_CPUS, sizeof(*sched.curr_thread));
+	if (!sched.curr_thread) {
+		ret = -ENOMEM;
+		goto out;
+	}
+	sched.cpu_last_switched = calloc(MAX_CPUS, sizeof(*sched.cpu_last_switched));
+	if (!sched.cpu_last_switched) {
+		ret = -ENOMEM;
+		goto out;
+	}
+	sched.curr_pid = malloc(MAX_CPUS * sizeof(*sched.curr_pid));
+	if (!sched.curr_pid) {
+		ret = -ENOMEM;
+		goto out;
+	}
+	for (i = 0; i < MAX_CPUS; i++)
 		sched.curr_pid[i] = -1;
 
 	argc = parse_options_subcommand(argc, argv, sched_options, sched_subcommands,
@@ -3659,6 +3674,9 @@ int cmd_sched(int argc, const char **argv)
 	}
 
 out:
+	free(sched.curr_pid);
+	free(sched.cpu_last_switched);
+	free(sched.curr_thread);
 	mutex_destroy(&sched.start_work_mutex);
 	mutex_destroy(&sched.work_done_wait_mutex);