* [PATCH v2] ipc, mqueue: lazy call kern_mount_data in new namespaces
@ 2017-11-30 18:38 Giuseppe Scrivano
2017-12-03 18:42 ` kbuild test robot
0 siblings, 1 reply; 2+ messages in thread
From: Giuseppe Scrivano @ 2017-11-30 18:38 UTC (permalink / raw)
To: linux-kernel; +Cc: gscrivan, Andrew Morton
kern_mount_data is a relatively expensive operation when creating a
new IPC namespace, so delay the mount until its first usage when not
creating the the global namespace.
This is a net saving for new IPC namespaces that don't use mq_open().
In this case there won't be any kern_mount_data() cost at all.
On my machine, the time for creating 1000 new IPC namespaces dropped
from ~8s to ~2s.
Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>
---
v1 here: https://lkml.org/lkml/2017/11/27/427
v1 -> v2:
Declare and use a mutex instead of a spinlock.
include/linux/ipc_namespace.h | 2 +-
ipc/mqueue.c | 48 ++++++++++++++++++++++++++++++++++---------
ipc/namespace.c | 2 +-
3 files changed, 40 insertions(+), 12 deletions(-)
diff --git a/include/linux/ipc_namespace.h b/include/linux/ipc_namespace.h
index b5630c8eb2f3..a06617c113f1 100644
--- a/include/linux/ipc_namespace.h
+++ b/include/linux/ipc_namespace.h
@@ -81,7 +81,7 @@ static inline void shm_destroy_orphaned(struct ipc_namespace *ns) {}
#endif /* CONFIG_SYSVIPC */
#ifdef CONFIG_POSIX_MQUEUE
-extern int mq_init_ns(struct ipc_namespace *ns);
+extern int mq_init_ns(struct ipc_namespace *ns, bool mount);
/*
* POSIX Message Queue default values:
*
diff --git a/ipc/mqueue.c b/ipc/mqueue.c
index d24025626310..27a82a3fef50 100644
--- a/ipc/mqueue.c
+++ b/ipc/mqueue.c
@@ -87,6 +87,7 @@ struct mqueue_inode_info {
unsigned long qsize; /* size of queue in memory (sum of all msgs) */
};
+static struct file_system_type mqueue_fs_type;
static const struct inode_operations mqueue_dir_inode_operations;
static const struct file_operations mqueue_file_operations;
static const struct super_operations mqueue_super_ops;
@@ -776,9 +777,24 @@ static int do_mq_open(const char __user *u_name, int oflag, umode_t mode,
struct filename *name;
int fd, error;
struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
- struct vfsmount *mnt = ipc_ns->mq_mnt;
- struct dentry *root = mnt->mnt_root;
+ struct vfsmount *mnt;
+ struct dentry *root;
int ro;
+ static DEFINE_MUTEX(mnt_lock);
+
+ mutex_lock(&mnt_lock);
+ mnt = ipc_ns->mq_mnt;
+ if (unlikely(!mnt)) {
+ mnt = kern_mount_data(&mqueue_fs_type, ipc_ns);
+ if (IS_ERR(mnt)) {
+ mutex_unlock(&mnt_lock);
+ return PTR_ERR(mnt);
+ }
+ ipc_ns->mq_mnt = mnt;
+ }
+ mutex_unlock(&mnt_lock);
+
+ root = mnt->mnt_root;
audit_mq_open(oflag, mode, attr);
@@ -863,6 +879,9 @@ SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name)
struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
struct vfsmount *mnt = ipc_ns->mq_mnt;
+ if (!mnt)
+ return -ENOENT;
+
name = getname(u_name);
if (IS_ERR(name))
return PTR_ERR(name);
@@ -1581,7 +1600,8 @@ static struct file_system_type mqueue_fs_type = {
.fs_flags = FS_USERNS_MOUNT,
};
-int mq_init_ns(struct ipc_namespace *ns)
+
+int mq_init_ns(struct ipc_namespace *ns, bool mount)
{
ns->mq_queues_count = 0;
ns->mq_queues_max = DFLT_QUEUESMAX;
@@ -1590,23 +1610,31 @@ int mq_init_ns(struct ipc_namespace *ns)
ns->mq_msg_default = DFLT_MSG;
ns->mq_msgsize_default = DFLT_MSGSIZE;
- ns->mq_mnt = kern_mount_data(&mqueue_fs_type, ns);
- if (IS_ERR(ns->mq_mnt)) {
- int err = PTR_ERR(ns->mq_mnt);
+ if (!mount)
ns->mq_mnt = NULL;
- return err;
+ else {
+ int err;
+
+ ns->mq_mnt = kern_mount_data(&mqueue_fs_type, ns);
+ if (IS_ERR(ns->mq_mnt)) {
+ err = PTR_ERR(ns->mq_mnt);
+ ns->mq_mnt = NULL;
+ return err;
+ }
}
return 0;
}
void mq_clear_sbinfo(struct ipc_namespace *ns)
{
- ns->mq_mnt->mnt_sb->s_fs_info = NULL;
+ if (ns->mq_mnt)
+ ns->mq_mnt->mnt_sb->s_fs_info = NULL;
}
void mq_put_mnt(struct ipc_namespace *ns)
{
- kern_unmount(ns->mq_mnt);
+ if (ns->mq_mnt)
+ kern_unmount(ns->mq_mnt);
}
static int __init init_mqueue_fs(void)
@@ -1628,7 +1656,7 @@ static int __init init_mqueue_fs(void)
spin_lock_init(&mq_lock);
- error = mq_init_ns(&init_ipc_ns);
+ error = mq_init_ns(&init_ipc_ns, true);
if (error)
goto out_filesystem;
diff --git a/ipc/namespace.c b/ipc/namespace.c
index f59a89966f92..9d3689577f66 100644
--- a/ipc/namespace.c
+++ b/ipc/namespace.c
@@ -65,7 +65,7 @@ static struct ipc_namespace *create_ipc_ns(struct user_namespace *user_ns,
if (err)
goto fail_destroy_msg;
- err = mq_init_ns(ns);
+ err = mq_init_ns(ns, false);
if (err)
goto fail_destroy_shm;
--
2.14.3
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH v2] ipc, mqueue: lazy call kern_mount_data in new namespaces
2017-11-30 18:38 [PATCH v2] ipc, mqueue: lazy call kern_mount_data in new namespaces Giuseppe Scrivano
@ 2017-12-03 18:42 ` kbuild test robot
0 siblings, 0 replies; 2+ messages in thread
From: kbuild test robot @ 2017-12-03 18:42 UTC (permalink / raw)
To: Giuseppe Scrivano; +Cc: kbuild-all, linux-kernel, gscrivan, Andrew Morton
[-- Attachment #1: Type: text/plain, Size: 7435 bytes --]
Hi Giuseppe,
Thank you for the patch! Yet something to improve:
[auto build test ERROR on linus/master]
[also build test ERROR on v4.15-rc2 next-20171201]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]
url: https://github.com/0day-ci/linux/commits/Giuseppe-Scrivano/ipc-mqueue-lazy-call-kern_mount_data-in-new-namespaces/20171203-201041
config: i386-randconfig-c0-12032036 (attached as .config)
compiler: gcc-7 (Debian 7.2.0-12) 7.2.1 20171025
reproduce:
# save the attached .config to linux build tree
make ARCH=i386
All errors (new ones prefixed by >>):
ipc/namespace.c: In function 'create_ipc_ns':
>> ipc/namespace.c:68:8: error: too many arguments to function 'mq_init_ns'
err = mq_init_ns(ns, false);
^~~~~~~~~~
In file included from ipc/namespace.c:9:0:
include/linux/ipc_namespace.h:119:19: note: declared here
static inline int mq_init_ns(struct ipc_namespace *ns) { return 0; }
^~~~~~~~~~
In file included from include/linux/kernel.h:10:0,
from include/linux/list.h:9,
from include/linux/preempt.h:11,
from include/linux/spinlock.h:51,
from include/linux/ipc.h:5,
from ipc/namespace.c:7:
ipc/namespace.c: At top level:
include/linux/compiler.h:64:4: warning: '______f' is static but declared in inline function 'strcpy' which is not static
______f = { \
^
include/linux/compiler.h:56:23: note: in expansion of macro '__trace_if'
#define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) )
^~~~~~~~~~
include/linux/string.h:422:2: note: in expansion of macro 'if'
if (p_size == (size_t)-1 && q_size == (size_t)-1)
^~
include/linux/compiler.h:64:4: warning: '______f' is static but declared in inline function 'kmemdup' which is not static
______f = { \
^
include/linux/compiler.h:56:23: note: in expansion of macro '__trace_if'
#define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) )
^~~~~~~~~~
include/linux/string.h:412:2: note: in expansion of macro 'if'
if (p_size < size)
^~
include/linux/compiler.h:64:4: warning: '______f' is static but declared in inline function 'kmemdup' which is not static
______f = { \
^
include/linux/compiler.h:56:23: note: in expansion of macro '__trace_if'
#define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) )
^~~~~~~~~~
include/linux/string.h:410:2: note: in expansion of macro 'if'
if (__builtin_constant_p(size) && p_size < size)
^~
include/linux/compiler.h:64:4: warning: '______f' is static but declared in inline function 'memchr_inv' which is not static
______f = { \
^
include/linux/compiler.h:56:23: note: in expansion of macro '__trace_if'
#define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) )
^~~~~~~~~~
include/linux/string.h:401:2: note: in expansion of macro 'if'
if (p_size < size)
^~
include/linux/compiler.h:64:4: warning: '______f' is static but declared in inline function 'memchr_inv' which is not static
______f = { \
^
include/linux/compiler.h:56:23: note: in expansion of macro '__trace_if'
#define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) )
^~~~~~~~~~
include/linux/string.h:399:2: note: in expansion of macro 'if'
if (__builtin_constant_p(size) && p_size < size)
^~
include/linux/compiler.h:64:4: warning: '______f' is static but declared in inline function 'memchr' which is not static
______f = { \
^
include/linux/compiler.h:56:23: note: in expansion of macro '__trace_if'
#define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) )
^~~~~~~~~~
include/linux/string.h:390:2: note: in expansion of macro 'if'
if (p_size < size)
^~
include/linux/compiler.h:64:4: warning: '______f' is static but declared in inline function 'memchr' which is not static
______f = { \
^
include/linux/compiler.h:56:23: note: in expansion of macro '__trace_if'
#define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) )
^~~~~~~~~~
include/linux/string.h:388:2: note: in expansion of macro 'if'
if (__builtin_constant_p(size) && p_size < size)
^~
include/linux/compiler.h:64:4: warning: '______f' is static but declared in inline function 'memcmp' which is not static
______f = { \
^
include/linux/compiler.h:56:23: note: in expansion of macro '__trace_if'
#define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) )
^~~~~~~~~~
include/linux/string.h:380:2: note: in expansion of macro 'if'
if (p_size < size || q_size < size)
^~
include/linux/compiler.h:64:4: warning: '______f' is static but declared in inline function 'memcmp' which is not static
______f = { \
^
include/linux/compiler.h:56:23: note: in expansion of macro '__trace_if'
#define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) )
^~~~~~~~~~
include/linux/string.h:377:3: note: in expansion of macro 'if'
if (q_size < size)
^~
include/linux/compiler.h:64:4: warning: '______f' is static but declared in inline function 'memcmp' which is not static
______f = { \
^
include/linux/compiler.h:56:23: note: in expansion of macro '__trace_if'
#define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) )
^~~~~~~~~~
vim +/mq_init_ns +68 ipc/namespace.c
31
32 static struct ipc_namespace *create_ipc_ns(struct user_namespace *user_ns,
33 struct ipc_namespace *old_ns)
34 {
35 struct ipc_namespace *ns;
36 struct ucounts *ucounts;
37 int err;
38
39 err = -ENOSPC;
40 ucounts = inc_ipc_namespaces(user_ns);
41 if (!ucounts)
42 goto fail;
43
44 err = -ENOMEM;
45 ns = kmalloc(sizeof(struct ipc_namespace), GFP_KERNEL);
46 if (ns == NULL)
47 goto fail_dec;
48
49 err = ns_alloc_inum(&ns->ns);
50 if (err)
51 goto fail_free;
52 ns->ns.ops = &ipcns_operations;
53
54 refcount_set(&ns->count, 1);
55 ns->user_ns = get_user_ns(user_ns);
56 ns->ucounts = ucounts;
57
58 err = sem_init_ns(ns);
59 if (err)
60 goto fail_put;
61 err = msg_init_ns(ns);
62 if (err)
63 goto fail_destroy_sem;
64 err = shm_init_ns(ns);
65 if (err)
66 goto fail_destroy_msg;
67
> 68 err = mq_init_ns(ns, false);
69 if (err)
70 goto fail_destroy_shm;
71
72 return ns;
73
74 fail_destroy_shm:
75 shm_exit_ns(ns);
76 fail_destroy_msg:
77 msg_exit_ns(ns);
78 fail_destroy_sem:
79 sem_exit_ns(ns);
80 fail_put:
81 put_user_ns(ns->user_ns);
82 ns_free_inum(&ns->ns);
83 fail_free:
84 kfree(ns);
85 fail_dec:
86 dec_ipc_namespaces(ucounts);
87 fail:
88 return ERR_PTR(err);
89 }
90
---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all Intel Corporation
[-- Attachment #2: .config.gz --]
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2017-11-30 18:38 [PATCH v2] ipc, mqueue: lazy call kern_mount_data in new namespaces Giuseppe Scrivano
2017-12-03 18:42 ` kbuild test robot
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