[PATCH] memory leaks triggered by perf --namespace

* [PATCH] memory leaks triggered by perf --namespace
@ 2017-11-15  5:47 Vasily Averin
  2017-11-15  8:51 ` [tip:perf/urgent] perf/core: Fix memory leak " tip-bot for Vasily Averin
  2017-11-29  6:15 ` tip-bot for Vasily Averin
  0 siblings, 2 replies; 3+ messages in thread
From: Vasily Averin @ 2017-11-15  5:47 UTC (permalink / raw)
  To: linux-kernel, Hari Bathini, Alexander Shishkin
  Cc: Namhyung Kim, Jiri Olsa, Arnaldo Carvalho de Melo, Ingo Molnar,
	Peter Zijlstra

perf with --namespace key leaks various memory objects including namespaces

# uname -r
4.14.0+
# perf record  -q  --namespace unshare -n -U  -p --fork true
# grep namespace /proc/slabinfo
pid_namespace          1     12   2568   12    8 
user_namespace         1     39    824   39    8 
net_namespace          1      5   6272    5    8 

This happen because perf_fill_ns_link_info() struct patch ns_path:
during initialization ns_path incremented counters on related mnt and dentry,
but without lost path_put nobody decremented them back.
Leaked dentry is name of related namespace,
and its leak does not allow to free unused namespace.

Fixes: commit e422267322cd ("perf: Add PERF_RECORD_NAMESPACES to include namespaces related info")
Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
---
 kernel/events/core.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 10cdb9c..ab5ac84 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -6756,6 +6756,7 @@ static void perf_fill_ns_link_info(struct perf_ns_link_info *ns_link_info,
 		ns_inode = ns_path.dentry->d_inode;
 		ns_link_info->dev = new_encode_dev(ns_inode->i_sb->s_dev);
 		ns_link_info->ino = ns_inode->i_ino;
+		path_put(&ns_path);
 	}
 }
 
-- 
2.7.4

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