From: "Alex Bennée" <alex.bennee@linaro.org>
To: qemu-devel@nongnu.org
Subject: [Qemu-devel] [Bug 1836558] [RFC PATCH for 4.1] linux-user: unparent CPU object before unref
Date: Tue, 16 Jul 2019 14:01:33 -0000 [thread overview]
Message-ID: <20190716140133.8578-1-alex.bennee@linaro.org> (raw)
Message-ID: <20190716140133.HWaqsJa-XbG6FMkUKEDZQ4dIwWO1QfmLzo_7d-vl5MY@z> (raw)
In-Reply-To: 156318593102.28533.3075291509963886255.malonedeb@chaenomeles.canonical.com
When a CPU object is created it is parented during it's realize stage.
If we don't unparent before the "final" unref we will never finzalize
the object leading to a memory leak. For most setups you probably
won't notice but with anything that creates and destroys a lot of
threads this will add up. This goes especially for architectures which
allocate a lot of memory in their CPU structures.
Fixes: https://bugs.launchpad.net/qemu/+bug/1836558
Cc: 1836558@bugs.launchpad.net
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
---
linux-user/syscall.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 39a37496fed..4c9313fd9d0 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -7183,6 +7183,7 @@ static abi_long do_syscall1(void *cpu_env, int num, abi_long arg1,
NULL, NULL, 0);
}
thread_cpu = NULL;
+ object_unparent(OBJECT(cpu));
object_unref(OBJECT(cpu));
g_free(ts);
rcu_unregister_thread();
--
2.20.1
--
You received this bug notification because you are a member of qemu-
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https://bugs.launchpad.net/bugs/1836558
Title:
Qemu-ppc Memory leak creating threads
Status in QEMU:
Confirmed
Bug description:
When creating c++ threads (with c++ std::thread), the resulting binary
has memory leaks when running with qemu-ppc.
Eg the following c++ program, when compiled with gcc, consumes more
and more memory while running at qemu-ppc. (does not have memory leaks
when compiling for Intel, when running same binary on real powerpc CPU
hardware also no memory leaks).
(Note I used function getCurrentRSS to show available memory, see
https://stackoverflow.com/questions/669438/how-to-get-memory-usage-at-
runtime-using-c; calls commented out here)
Compiler: powerpc-linux-gnu-g++ (Debian 8.3.0-2) 8.3.0 (but same problem with older g++ compilers even 4.9)
Os: Debian 10.0 ( Buster) (but same problem seen on Debian 9/stetch)
qemu: qemu-ppc version 3.1.50
---
#include <iostream>
#include <thread>
#include <chrono>
using namespace std::chrono_literals;
// Create/run and join a 100 threads.
void Fun100()
{
// auto b4 = getCurrentRSS();
// std::cout << getCurrentRSS() << std::endl;
for(int n = 0; n < 100; n++)
{
std::thread t([]
{
std::this_thread::sleep_for( 10ms );
});
// std::cout << n << ' ' << getCurrentRSS() << std::endl;
t.join();
}
std::this_thread::sleep_for( 500ms ); // to give OS some time to wipe memory...
// auto after = getCurrentRSS();
std::cout << b4 << ' ' << after << std::endl;
}
int main(int, char **)
{
Fun100();
Fun100(); // memory used keeps increasing
}
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1836558/+subscriptions
next prev parent reply other threads:[~2019-07-16 14:16 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-15 10:18 [Qemu-devel] [Bug 1836558] [NEW] Qemu-ppc Memory leak creating threads Daan Scherft
2019-07-15 13:34 ` [Qemu-devel] [Bug 1836558] " Daan Scherft
2019-07-15 14:15 ` Alex Bennée
2019-07-15 15:10 ` Daan Scherft
2019-07-15 15:52 ` Alex Bennée
2019-07-15 16:21 ` Alex Bennée
2019-07-15 16:50 ` Alex Bennée
2019-07-16 12:13 ` [Qemu-devel] [RFC PATCH for 4.1?] target/ppc: move opcode decode tables to PowerPCCPU Alex Bennée
2019-07-16 12:13 ` [Qemu-devel] [Bug 1836558] " Alex Bennée
2019-07-16 14:50 ` [Qemu-devel] " Richard Henderson
2019-07-17 1:33 ` David Gibson
2019-07-17 9:41 ` Alex Bennée
2019-07-17 9:41 ` [Qemu-devel] [Bug 1836558] " Alex Bennée
2019-07-17 12:13 ` [Qemu-devel] " no-reply
2019-07-16 14:01 ` Alex Bennée [this message]
2019-07-16 14:01 ` [Qemu-devel] [Bug 1836558] [RFC PATCH for 4.1] linux-user: unparent CPU object before unref Alex Bennée
2019-07-16 14:43 ` [Qemu-devel] " Peter Maydell
2019-07-16 14:43 ` [Qemu-devel] [Bug 1836558] " Peter Maydell
2019-07-16 15:02 ` [Qemu-devel] " Alex Bennée
2019-07-16 15:02 ` [Qemu-devel] [Bug 1836558] " Alex Bennée
2019-07-16 15:17 ` [Qemu-devel] " Philippe Mathieu-Daudé
2020-01-09 13:22 ` [Bug 1836558] Re: Qemu-ppc Memory leak creating threads Thomas Huth
2020-03-10 8:48 ` Laurent Vivier
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