linux-kernel - [PATCH 22/37] perf machine: Fix machine__destroy_kernel_maps to drop vmlinux

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Message-Id: <1447955603-24895-23-git-send-email-acme@kernel.org>
Date:	Thu, 19 Nov 2015 14:53:08 -0300
From:	Arnaldo Carvalho de Melo <acme@...nel.org>
To:	Ingo Molnar <mingo@...nel.org>
Cc:	linux-kernel@...r.kernel.org,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Jiri Olsa <jolsa@...hat.com>,
	Namhyung Kim <namhyung@...nel.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Arnaldo Carvalho de Melo <acme@...hat.com>
Subject: [PATCH 22/37] perf machine: Fix machine__destroy_kernel_maps to drop vmlinux_maps references

From: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>

Fix machine__destroy_kernel_maps() to drop vmlinux_maps references
before filling it with NULL.

Refcnt debugger shows
  ==== [1] ====
  Unreclaimed map: 0x36b1070
  Refcount +1 => 1 at
    ./perf(map__new2+0xb5) [0x4bdec5]
    ./perf(machine__create_kernel_maps+0x72) [0x4bb152]
    ./perf(machine__new_host+0xfa) [0x4bb41a]
    ./perf(init_probe_symbol_maps+0x93) [0x5062d3]
    ./perf() [0x455ffa]
    ./perf(cmd_probe+0x6c) [0x4566bc]
    ./perf() [0x47abc5]
    ./perf(main+0x610) [0x421f90]
    /lib64/libc.so.6(__libc_start_main+0xf5) [0x7f1fc9fc4af5]
    ./perf() [0x4220a9]
  Refcount +1 => 2 at
    ./perf(maps__insert+0x9a) [0x4bfd6a]
    ./perf(machine__create_kernel_maps+0xc3) [0x4bb1a3]
    ./perf(machine__new_host+0xfa) [0x4bb41a]
    ./perf(init_probe_symbol_maps+0x93) [0x5062d3]
    ./perf() [0x455ffa]
    ./perf(cmd_probe+0x6c) [0x4566bc]
    ./perf() [0x47abc5]
    ./perf(main+0x610) [0x421f90]
    /lib64/libc.so.6(__libc_start_main+0xf5) [0x7f1fc9fc4af5]
    ./perf() [0x4220a9]
  Refcount -1 => 1 at
    ./perf(map_groups__exit+0x94) [0x4bea74]
    ./perf(machine__delete+0x3d) [0x4b91fd]
    ./perf(exit_probe_symbol_maps+0x28) [0x506378]
    ./perf() [0x45628a]
    ./perf(cmd_probe+0x6c) [0x4566bc]
    ./perf() [0x47abc5]
    ./perf(main+0x610) [0x421f90]
    /lib64/libc.so.6(__libc_start_main+0xf5) [0x7f1fc9fc4af5]
    ./perf() [0x4220a9]

map__new2() returns map with refcnt = 1, and also map_groups__insert
gets it again in__machine__create_kernel_maps().

machine__destroy_kernel_maps() calls map_groups__remove() to
decrement the refcnt, but before decrement it again (corresponding
to map__new2), it makes vmlinux_maps[type] = NULL. And this may
cause a refcnt leak.

Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
Cc: Adrian Hunter <adrian.hunter@...el.com>
Cc: Jiri Olsa <jolsa@...hat.com>
Cc: Namhyung Kim <namhyung@...nel.org>
Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Link: http://lkml.kernel.org/r/20151118064022.30709.3897.stgit@localhost.localdomain
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---
 tools/perf/util/machine.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index 0487d7795f13..e9e09bee221c 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -790,6 +790,7 @@ void machine__destroy_kernel_maps(struct machine *machine)
 				kmap->ref_reloc_sym = NULL;
 		}
 
+		map__put(machine->vmlinux_maps[type]);
 		machine->vmlinux_maps[type] = NULL;
 	}
 }
-- 
2.1.0

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