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authorSeongJae Park <sjpark@amazon.de>2021-09-07 19:56:57 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2021-09-08 11:50:25 -0700
commit429538e85410c3ae12719ec42b89ab873ed6d47b (patch)
tree8d6b40dbcdef55b67ac9f5e80ec911b34a6d6d4e /mm
parent4bc05954d0076655cfaf6f0135585bdc20cd6b11 (diff)
downloadlinux-429538e85410c3ae12719ec42b89ab873ed6d47b.tar.bz2
mm/damon/dbgfs: export kdamond pid to the user space
For CPU usage accounting, knowing pid of the monitoring thread could be helpful. For example, users could use cpuaccount cgroups with the pid. This commit therefore exports the pid of currently running monitoring thread to the user space via 'kdamond_pid' file in the debugfs directory. Link: https://lkml.kernel.org/r/20210716081449.22187-9-sj38.park@gmail.com Signed-off-by: SeongJae Park <sjpark@amazon.de> Reviewed-by: Fernand Sieber <sieberf@amazon.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Amit Shah <amit@kernel.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Brendan Higgins <brendanhiggins@google.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: David Woodhouse <dwmw@amazon.com> Cc: Fan Du <fan.du@intel.com> Cc: Greg Kroah-Hartman <greg@kroah.com> Cc: Greg Thelen <gthelen@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Joe Perches <joe@perches.com> Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Leonard Foerster <foersleo@amazon.de> Cc: Marco Elver <elver@google.com> Cc: Markus Boehme <markubo@amazon.de> Cc: Maximilian Heyne <mheyne@amazon.de> Cc: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan@kernel.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Steven Rostedt (VMware) <rostedt@goodmis.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/damon/dbgfs.c37
1 files changed, 35 insertions, 2 deletions
diff --git a/mm/damon/dbgfs.c b/mm/damon/dbgfs.c
index d2e0a547eb3f..e850be4077f5 100644
--- a/mm/damon/dbgfs.c
+++ b/mm/damon/dbgfs.c
@@ -239,6 +239,32 @@ out:
return ret;
}
+static ssize_t dbgfs_kdamond_pid_read(struct file *file,
+ char __user *buf, size_t count, loff_t *ppos)
+{
+ struct damon_ctx *ctx = file->private_data;
+ char *kbuf;
+ ssize_t len;
+
+ kbuf = kmalloc(count, GFP_KERNEL);
+ if (!kbuf)
+ return -ENOMEM;
+
+ mutex_lock(&ctx->kdamond_lock);
+ if (ctx->kdamond)
+ len = scnprintf(kbuf, count, "%d\n", ctx->kdamond->pid);
+ else
+ len = scnprintf(kbuf, count, "none\n");
+ mutex_unlock(&ctx->kdamond_lock);
+ if (!len)
+ goto out;
+ len = simple_read_from_buffer(buf, count, ppos, kbuf, len);
+
+out:
+ kfree(kbuf);
+ return len;
+}
+
static int damon_dbgfs_open(struct inode *inode, struct file *file)
{
file->private_data = inode->i_private;
@@ -258,10 +284,17 @@ static const struct file_operations target_ids_fops = {
.write = dbgfs_target_ids_write,
};
+static const struct file_operations kdamond_pid_fops = {
+ .open = damon_dbgfs_open,
+ .read = dbgfs_kdamond_pid_read,
+};
+
static void dbgfs_fill_ctx_dir(struct dentry *dir, struct damon_ctx *ctx)
{
- const char * const file_names[] = {"attrs", "target_ids"};
- const struct file_operations *fops[] = {&attrs_fops, &target_ids_fops};
+ const char * const file_names[] = {"attrs", "target_ids",
+ "kdamond_pid"};
+ const struct file_operations *fops[] = {&attrs_fops, &target_ids_fops,
+ &kdamond_pid_fops};
int i;
for (i = 0; i < ARRAY_SIZE(file_names); i++)