* [PATCH] fs, ipc: Use an asynchronous version of kern_unmount in IPC
@ 2019-02-06 19:53 Salman Qazi
2019-02-06 20:13 ` Eric Dumazet
2019-02-07 4:14 ` Al Viro
0 siblings, 2 replies; 6+ messages in thread
From: Salman Qazi @ 2019-02-06 19:53 UTC (permalink / raw)
To: Alexander Viro, Eric Biederman, Eric Dumazet, linux-fsdevel; +Cc: Salman Qazi
Prior to this patch, the kernel can spend a lot of time with
this stack trace:
[<ffffffffbe5491e3>] __wait_rcu_gp+0x93/0xe0
[<ffffffffbe549418>] synchronize_sched+0x48/0x60
[<ffffffffbe7ae5b3>] kern_unmount+0x3a/0x46
[<ffffffffbe847c02>] mq_put_mnt+0x15/0x17
[<ffffffffbe8481af>] put_ipc_ns+0x36/0x8b
This patch solves the issue by removing synchronize_rcu from mq_put_mnt.
This is done by implementing an asynchronous version of kern_unmount.
Since mntput() sleeps, it needs to be deferred to a work queue.
Additionally, the callers of mq_put_mnt appear to be safe having
it behave asynchronously. In particular, put_ipc_ns calls
mq_clear_sbinfo which renders the inode inaccessible for the purposes of
mqueue_create by making s_fs_info NULL. This appears
to be the thing that prevents access while free_ipc_ns is taking place.
So, the unmount should be able to proceed lazily.
Tested: Ran the following program:
int main(void)
{
int pid;
int status;
int i;
for (i = 0; i < 1000; i++) {
pid = fork();
if (!pid) {
assert(!unshare(CLONE_NEWUSER|
CLONE_NEWIPC|CLONE_NEWNS));
return 0;
}
assert(waitpid(pid, &status, 0) == pid);
}
}
Before:
$ time ./unshare2
real 0m9.784s
user 0m0.428s
sys 0m0.000s
After:
$ time ./unshare2
real 0m0.368s
user 0m0.226s
sys 0m0.122s
Signed-off-by: Salman Qazi <sqazi@google.com>
---
fs/namespace.c | 41 +++++++++++++++++++++++++++++++++++++++++
include/linux/fs.h | 1 +
ipc/mqueue.c | 2 +-
3 files changed, 43 insertions(+), 1 deletion(-)
diff --git a/fs/namespace.c b/fs/namespace.c
index a677b59efd74..caa51ca81605 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -3323,6 +3323,47 @@ void kern_unmount(struct vfsmount *mnt)
}
EXPORT_SYMBOL(kern_unmount);
+struct async_unmount_cb {
+ struct vfsmount *mnt;
+ struct work_struct work;
+ struct rcu_head rcu_head;
+};
+
+static void kern_unmount_work(struct work_struct *work)
+{
+ struct async_unmount_cb *cb = container_of(work,
+ struct async_unmount_cb, work);
+
+ mntput(cb->mnt);
+ kfree(cb);
+}
+
+static void kern_unmount_rcu_cb(struct rcu_head *rcu_head)
+{
+ struct async_unmount_cb *cb = container_of(rcu_head,
+ struct async_unmount_cb, rcu_head);
+
+ INIT_WORK(&cb->work, kern_unmount_work);
+ schedule_work(&cb->work);
+
+}
+
+void kern_unmount_async(struct vfsmount *mnt)
+{
+ /* release long term mount so mount point can be released */
+ if (!IS_ERR_OR_NULL(mnt)) {
+ struct async_unmount_cb *cb = kmalloc(sizeof(*cb), GFP_KERNEL);
+
+ if (cb) {
+ real_mount(mnt)->mnt_ns = NULL;
+ cb->mnt = mnt;
+ call_rcu(&cb->rcu_head, kern_unmount_rcu_cb);
+ } else {
+ kern_unmount(mnt);
+ }
+ }
+}
+
bool our_mnt(struct vfsmount *mnt)
{
return check_mnt(real_mount(mnt));
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 29d8e2cfed0e..8865997a8722 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2274,6 +2274,7 @@ extern int register_filesystem(struct file_system_type *);
extern int unregister_filesystem(struct file_system_type *);
extern struct vfsmount *kern_mount_data(struct file_system_type *, void *data);
#define kern_mount(type) kern_mount_data(type, NULL)
+extern void kern_unmount_async(struct vfsmount *mnt);
extern void kern_unmount(struct vfsmount *mnt);
extern int may_umount_tree(struct vfsmount *);
extern int may_umount(struct vfsmount *);
diff --git a/ipc/mqueue.c b/ipc/mqueue.c
index c595bed7bfcb..a8c2465ac0cb 100644
--- a/ipc/mqueue.c
+++ b/ipc/mqueue.c
@@ -1554,7 +1554,7 @@ void mq_clear_sbinfo(struct ipc_namespace *ns)
void mq_put_mnt(struct ipc_namespace *ns)
{
- kern_unmount(ns->mq_mnt);
+ kern_unmount_async(ns->mq_mnt);
}
static int __init init_mqueue_fs(void)
--
2.20.1.611.gfbb209baf1-goog
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH] fs, ipc: Use an asynchronous version of kern_unmount in IPC
2019-02-06 19:53 [PATCH] fs, ipc: Use an asynchronous version of kern_unmount in IPC Salman Qazi
@ 2019-02-06 20:13 ` Eric Dumazet
2019-02-07 4:14 ` Al Viro
1 sibling, 0 replies; 6+ messages in thread
From: Eric Dumazet @ 2019-02-06 20:13 UTC (permalink / raw)
To: Salman Qazi; +Cc: Alexander Viro, Eric Biederman, linux-fsdevel, LKML
On Wed, Feb 6, 2019 at 11:54 AM Salman Qazi <sqazi@google.com> wrote:
>
> Prior to this patch, the kernel can spend a lot of time with
> this stack trace:
>
> [<ffffffffbe5491e3>] __wait_rcu_gp+0x93/0xe0
> [<ffffffffbe549418>] synchronize_sched+0x48/0x60
> [<ffffffffbe7ae5b3>] kern_unmount+0x3a/0x46
> [<ffffffffbe847c02>] mq_put_mnt+0x15/0x17
> [<ffffffffbe8481af>] put_ipc_ns+0x36/0x8b
>
> This patch solves the issue by removing synchronize_rcu from mq_put_mnt.
> This is done by implementing an asynchronous version of kern_unmount.
>
> Since mntput() sleeps, it needs to be deferred to a work queue.
>
> Additionally, the callers of mq_put_mnt appear to be safe having
> it behave asynchronously. In particular, put_ipc_ns calls
> mq_clear_sbinfo which renders the inode inaccessible for the purposes of
> mqueue_create by making s_fs_info NULL. This appears
> to be the thing that prevents access while free_ipc_ns is taking place.
> So, the unmount should be able to proceed lazily.
>
> Tested: Ran the following program:
>
> int main(void)
> {
> int pid;
> int status;
> int i;
>
> for (i = 0; i < 1000; i++) {
> pid = fork();
> if (!pid) {
> assert(!unshare(CLONE_NEWUSER|
> CLONE_NEWIPC|CLONE_NEWNS));
> return 0;
> }
>
> assert(waitpid(pid, &status, 0) == pid);
> }
> }
>
> Before:
>
> $ time ./unshare2
>
> real 0m9.784s
> user 0m0.428s
> sys 0m0.000s
>
> After:
>
> $ time ./unshare2
>
> real 0m0.368s
> user 0m0.226s
> sys 0m0.122s
>
> Signed-off-by: Salman Qazi <sqazi@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
> ---
> fs/namespace.c | 41 +++++++++++++++++++++++++++++++++++++++++
> include/linux/fs.h | 1 +
> ipc/mqueue.c | 2 +-
> 3 files changed, 43 insertions(+), 1 deletion(-)
>
> diff --git a/fs/namespace.c b/fs/namespace.c
> index a677b59efd74..caa51ca81605 100644
> --- a/fs/namespace.c
> +++ b/fs/namespace.c
> @@ -3323,6 +3323,47 @@ void kern_unmount(struct vfsmount *mnt)
> }
> EXPORT_SYMBOL(kern_unmount);
>
> +struct async_unmount_cb {
> + struct vfsmount *mnt;
> + struct work_struct work;
> + struct rcu_head rcu_head;
> +};
> +
> +static void kern_unmount_work(struct work_struct *work)
> +{
> + struct async_unmount_cb *cb = container_of(work,
> + struct async_unmount_cb, work);
> +
> + mntput(cb->mnt);
> + kfree(cb);
> +}
> +
> +static void kern_unmount_rcu_cb(struct rcu_head *rcu_head)
> +{
> + struct async_unmount_cb *cb = container_of(rcu_head,
> + struct async_unmount_cb, rcu_head);
> +
> + INIT_WORK(&cb->work, kern_unmount_work);
> + schedule_work(&cb->work);
> +
> +}
> +
> +void kern_unmount_async(struct vfsmount *mnt)
> +{
> + /* release long term mount so mount point can be released */
> + if (!IS_ERR_OR_NULL(mnt)) {
> + struct async_unmount_cb *cb = kmalloc(sizeof(*cb), GFP_KERNEL);
> +
> + if (cb) {
> + real_mount(mnt)->mnt_ns = NULL;
> + cb->mnt = mnt;
> + call_rcu(&cb->rcu_head, kern_unmount_rcu_cb);
> + } else {
> + kern_unmount(mnt);
> + }
> + }
> +}
> +
> bool our_mnt(struct vfsmount *mnt)
> {
> return check_mnt(real_mount(mnt));
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 29d8e2cfed0e..8865997a8722 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -2274,6 +2274,7 @@ extern int register_filesystem(struct file_system_type *);
> extern int unregister_filesystem(struct file_system_type *);
> extern struct vfsmount *kern_mount_data(struct file_system_type *, void *data);
> #define kern_mount(type) kern_mount_data(type, NULL)
> +extern void kern_unmount_async(struct vfsmount *mnt);
> extern void kern_unmount(struct vfsmount *mnt);
> extern int may_umount_tree(struct vfsmount *);
> extern int may_umount(struct vfsmount *);
> diff --git a/ipc/mqueue.c b/ipc/mqueue.c
> index c595bed7bfcb..a8c2465ac0cb 100644
> --- a/ipc/mqueue.c
> +++ b/ipc/mqueue.c
> @@ -1554,7 +1554,7 @@ void mq_clear_sbinfo(struct ipc_namespace *ns)
>
> void mq_put_mnt(struct ipc_namespace *ns)
> {
> - kern_unmount(ns->mq_mnt);
> + kern_unmount_async(ns->mq_mnt);
> }
>
> static int __init init_mqueue_fs(void)
> --
> 2.20.1.611.gfbb209baf1-goog
>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] fs, ipc: Use an asynchronous version of kern_unmount in IPC
2019-02-06 19:53 [PATCH] fs, ipc: Use an asynchronous version of kern_unmount in IPC Salman Qazi
2019-02-06 20:13 ` Eric Dumazet
@ 2019-02-07 4:14 ` Al Viro
2019-02-07 18:43 ` Salman Qazi
1 sibling, 1 reply; 6+ messages in thread
From: Al Viro @ 2019-02-07 4:14 UTC (permalink / raw)
To: Salman Qazi; +Cc: Eric Biederman, Eric Dumazet, linux-fsdevel
On Wed, Feb 06, 2019 at 11:53:54AM -0800, Salman Qazi wrote:
> This patch solves the issue by removing synchronize_rcu from mq_put_mnt.
> This is done by implementing an asynchronous version of kern_unmount.
>
> Since mntput() sleeps, it needs to be deferred to a work queue.
>
> Additionally, the callers of mq_put_mnt appear to be safe having
> it behave asynchronously. In particular, put_ipc_ns calls
> mq_clear_sbinfo which renders the inode inaccessible for the purposes of
> mqueue_create by making s_fs_info NULL. This appears
> to be the thing that prevents access while free_ipc_ns is taking place.
> So, the unmount should be able to proceed lazily.
Ugh... I really doubt that it's correct. The caller is
mq_put_mnt(ns);
free_ipc_ns(ns);
and we have
static void mqueue_evict_inode(struct inode *inode)
{
...
ipc_ns = get_ns_from_inode(inode);
with
static struct ipc_namespace *get_ns_from_inode(struct inode *inode)
{
struct ipc_namespace *ns;
spin_lock(&mq_lock);
ns = __get_ns_from_inode(inode);
spin_unlock(&mq_lock);
return ns;
}
and
static inline struct ipc_namespace *__get_ns_from_inode(struct inode *inode)
{
return get_ipc_ns(inode->i_sb->s_fs_info);
}
with ->s_fs_info being the ipc_namespace we are freeing after mq_put_ns()
Are you saying that get_ipc_ns() after free_ipc_ns() is safe? Because
->evict_inode() *IS* called on umount. What happens to your patch if
there was a regular file left on that filesystem?
Smells like a memory corruptor...
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] fs, ipc: Use an asynchronous version of kern_unmount in IPC
2019-02-07 4:14 ` Al Viro
@ 2019-02-07 18:43 ` Salman Qazi
2019-02-13 21:07 ` Salman Qazi
2019-03-04 19:48 ` [PATCH RESENT] " Salman Qazi
0 siblings, 2 replies; 6+ messages in thread
From: Salman Qazi @ 2019-02-07 18:43 UTC (permalink / raw)
To: Al Viro; +Cc: Eric Biederman, Eric Dumazet, linux-fsdevel
On Wed, Feb 6, 2019 at 8:14 PM Al Viro <viro@zeniv.linux.org.uk> wrote:
>
> On Wed, Feb 06, 2019 at 11:53:54AM -0800, Salman Qazi wrote:
>
> > This patch solves the issue by removing synchronize_rcu from mq_put_mnt.
> > This is done by implementing an asynchronous version of kern_unmount.
> >
> > Since mntput() sleeps, it needs to be deferred to a work queue.
> >
> > Additionally, the callers of mq_put_mnt appear to be safe having
> > it behave asynchronously. In particular, put_ipc_ns calls
> > mq_clear_sbinfo which renders the inode inaccessible for the purposes of
> > mqueue_create by making s_fs_info NULL. This appears
> > to be the thing that prevents access while free_ipc_ns is taking place.
> > So, the unmount should be able to proceed lazily.
>
> Ugh... I really doubt that it's correct. The caller is
> mq_put_mnt(ns);
> free_ipc_ns(ns);
> and we have
> static void mqueue_evict_inode(struct inode *inode)
> {
>
> ...
>
> ipc_ns = get_ns_from_inode(inode);
>
> with
>
> static struct ipc_namespace *get_ns_from_inode(struct inode *inode)
> {
> struct ipc_namespace *ns;
>
> spin_lock(&mq_lock);
> ns = __get_ns_from_inode(inode);
> spin_unlock(&mq_lock);
> return ns;
> }
>
> and
>
> static inline struct ipc_namespace *__get_ns_from_inode(struct inode *inode)
> {
> return get_ipc_ns(inode->i_sb->s_fs_info);
> }
>
> with ->s_fs_info being the ipc_namespace we are freeing after mq_put_ns()
>
> Are you saying that get_ipc_ns() after free_ipc_ns() is safe? Because
> ->evict_inode() *IS* called on umount. What happens to your patch if
> there was a regular file left on that filesystem?
>
> Smells like a memory corruptor...
Actually, the full context in the caller is
if (refcount_dec_and_lock(&ns->count, &mq_lock)) {
mq_clear_sbinfo(ns);
spin_unlock(&mq_lock);
mq_put_mnt(ns);
free_ipc_ns(ns);
}
And
void mq_clear_sbinfo(struct ipc_namespace *ns)
{
ns->mq_mnt->mnt_sb->s_fs_info = NULL;
}
Therefore, s_fs_info should be NULL before we proceed to unmount. So,
as far as I know, it should not be possible to find the ipc_namespace
from the mount.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] fs, ipc: Use an asynchronous version of kern_unmount in IPC
2019-02-07 18:43 ` Salman Qazi
@ 2019-02-13 21:07 ` Salman Qazi
2019-03-04 19:48 ` [PATCH RESENT] " Salman Qazi
1 sibling, 0 replies; 6+ messages in thread
From: Salman Qazi @ 2019-02-13 21:07 UTC (permalink / raw)
To: Al Viro
Cc: Eric Biederman, Eric Dumazet, linux-fsdevel, Linux Kernel Mailing List
Do you have any additional concerns?
On Thu, Feb 7, 2019 at 10:43 AM Salman Qazi <sqazi@google.com> wrote:
>
> On Wed, Feb 6, 2019 at 8:14 PM Al Viro <viro@zeniv.linux.org.uk> wrote:
> >
> > On Wed, Feb 06, 2019 at 11:53:54AM -0800, Salman Qazi wrote:
> >
> > > This patch solves the issue by removing synchronize_rcu from mq_put_mnt.
> > > This is done by implementing an asynchronous version of kern_unmount.
> > >
> > > Since mntput() sleeps, it needs to be deferred to a work queue.
> > >
> > > Additionally, the callers of mq_put_mnt appear to be safe having
> > > it behave asynchronously. In particular, put_ipc_ns calls
> > > mq_clear_sbinfo which renders the inode inaccessible for the purposes of
> > > mqueue_create by making s_fs_info NULL. This appears
> > > to be the thing that prevents access while free_ipc_ns is taking place.
> > > So, the unmount should be able to proceed lazily.
> >
> > Ugh... I really doubt that it's correct. The caller is
> > mq_put_mnt(ns);
> > free_ipc_ns(ns);
> > and we have
> > static void mqueue_evict_inode(struct inode *inode)
> > {
> >
> > ...
> >
> > ipc_ns = get_ns_from_inode(inode);
> >
> > with
> >
> > static struct ipc_namespace *get_ns_from_inode(struct inode *inode)
> > {
> > struct ipc_namespace *ns;
> >
> > spin_lock(&mq_lock);
> > ns = __get_ns_from_inode(inode);
> > spin_unlock(&mq_lock);
> > return ns;
> > }
> >
> > and
> >
> > static inline struct ipc_namespace *__get_ns_from_inode(struct inode *inode)
> > {
> > return get_ipc_ns(inode->i_sb->s_fs_info);
> > }
> >
> > with ->s_fs_info being the ipc_namespace we are freeing after mq_put_ns()
> >
> > Are you saying that get_ipc_ns() after free_ipc_ns() is safe? Because
> > ->evict_inode() *IS* called on umount. What happens to your patch if
> > there was a regular file left on that filesystem?
> >
> > Smells like a memory corruptor...
>
> Actually, the full context in the caller is
>
> if (refcount_dec_and_lock(&ns->count, &mq_lock)) {
> mq_clear_sbinfo(ns);
> spin_unlock(&mq_lock);
> mq_put_mnt(ns);
> free_ipc_ns(ns);
> }
>
> And
>
> void mq_clear_sbinfo(struct ipc_namespace *ns)
> {
> ns->mq_mnt->mnt_sb->s_fs_info = NULL;
> }
>
> Therefore, s_fs_info should be NULL before we proceed to unmount. So,
> as far as I know, it should not be possible to find the ipc_namespace
> from the mount.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH RESENT] fs, ipc: Use an asynchronous version of kern_unmount in IPC
2019-02-07 18:43 ` Salman Qazi
2019-02-13 21:07 ` Salman Qazi
@ 2019-03-04 19:48 ` Salman Qazi
1 sibling, 0 replies; 6+ messages in thread
From: Salman Qazi @ 2019-03-04 19:48 UTC (permalink / raw)
To: Al Viro, Eric Biederman, Eric Dumazet, linux-fsdevel, LKML; +Cc: Salman Qazi
Prior to this patch, the kernel can spend a lot of time with
this stack trace:
[<ffffffffbe5491e3>] __wait_rcu_gp+0x93/0xe0
[<ffffffffbe549418>] synchronize_sched+0x48/0x60
[<ffffffffbe7ae5b3>] kern_unmount+0x3a/0x46
[<ffffffffbe847c02>] mq_put_mnt+0x15/0x17
[<ffffffffbe8481af>] put_ipc_ns+0x36/0x8b
This patch solves the issue by removing synchronize_rcu from mq_put_mnt.
This is done by implementing an asynchronous version of kern_unmount.
Since mntput() sleeps, it needs to be deferred to a work queue.
Additionally, the callers of mq_put_mnt appear to be safe having
it behave asynchronously. In particular, put_ipc_ns calls
mq_clear_sbinfo which renders the inode inaccessible for the purposes of
mqueue_create by making s_fs_info NULL. This appears
to be the thing that prevents access while free_ipc_ns is taking place.
So, the unmount should be able to proceed lazily.
Tested: Ran the following program:
int main(void)
{
int pid;
int status;
int i;
for (i = 0; i < 1000; i++) {
pid = fork();
if (!pid) {
assert(!unshare(CLONE_NEWUSER|
CLONE_NEWIPC|CLONE_NEWNS));
return 0;
}
assert(waitpid(pid, &status, 0) == pid);
}
}
Before:
$ time ./unshare2
real 0m9.784s
user 0m0.428s
sys 0m0.000s
After:
$ time ./unshare2
real 0m0.368s
user 0m0.226s
sys 0m0.122s
Signed-off-by: Salman Qazi <sqazi@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
---
fs/namespace.c | 41 +++++++++++++++++++++++++++++++++++++++++
include/linux/fs.h | 1 +
ipc/mqueue.c | 2 +-
3 files changed, 43 insertions(+), 1 deletion(-)
diff --git a/fs/namespace.c b/fs/namespace.c
index 678ef175d63a..e60b473c3bbc 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -3321,6 +3321,47 @@ void kern_unmount(struct vfsmount *mnt)
}
EXPORT_SYMBOL(kern_unmount);
+struct async_unmount_cb {
+ struct vfsmount *mnt;
+ struct work_struct work;
+ struct rcu_head rcu_head;
+};
+
+static void kern_unmount_work(struct work_struct *work)
+{
+ struct async_unmount_cb *cb = container_of(work,
+ struct async_unmount_cb, work);
+
+ mntput(cb->mnt);
+ kfree(cb);
+}
+
+static void kern_unmount_rcu_cb(struct rcu_head *rcu_head)
+{
+ struct async_unmount_cb *cb = container_of(rcu_head,
+ struct async_unmount_cb, rcu_head);
+
+ INIT_WORK(&cb->work, kern_unmount_work);
+ schedule_work(&cb->work);
+
+}
+
+void kern_unmount_async(struct vfsmount *mnt)
+{
+ /* release long term mount so mount point can be released */
+ if (!IS_ERR_OR_NULL(mnt)) {
+ struct async_unmount_cb *cb = kmalloc(sizeof(*cb), GFP_KERNEL);
+
+ if (cb) {
+ real_mount(mnt)->mnt_ns = NULL;
+ cb->mnt = mnt;
+ call_rcu(&cb->rcu_head, kern_unmount_rcu_cb);
+ } else {
+ kern_unmount(mnt);
+ }
+ }
+}
+
bool our_mnt(struct vfsmount *mnt)
{
return check_mnt(real_mount(mnt));
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 29d8e2cfed0e..8865997a8722 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2274,6 +2274,7 @@ extern int register_filesystem(struct file_system_type *);
extern int unregister_filesystem(struct file_system_type *);
extern struct vfsmount *kern_mount_data(struct file_system_type *, void *data);
#define kern_mount(type) kern_mount_data(type, NULL)
+extern void kern_unmount_async(struct vfsmount *mnt);
extern void kern_unmount(struct vfsmount *mnt);
extern int may_umount_tree(struct vfsmount *);
extern int may_umount(struct vfsmount *);
diff --git a/ipc/mqueue.c b/ipc/mqueue.c
index c595bed7bfcb..a8c2465ac0cb 100644
--- a/ipc/mqueue.c
+++ b/ipc/mqueue.c
@@ -1554,7 +1554,7 @@ void mq_clear_sbinfo(struct ipc_namespace *ns)
void mq_put_mnt(struct ipc_namespace *ns)
{
- kern_unmount(ns->mq_mnt);
+ kern_unmount_async(ns->mq_mnt);
}
static int __init init_mqueue_fs(void)
--
2.21.0.352.gf09ad66450-goog
^ permalink raw reply related [flat|nested] 6+ messages in thread
end of thread, other threads:[~2019-03-04 19:49 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-02-06 19:53 [PATCH] fs, ipc: Use an asynchronous version of kern_unmount in IPC Salman Qazi
2019-02-06 20:13 ` Eric Dumazet
2019-02-07 4:14 ` Al Viro
2019-02-07 18:43 ` Salman Qazi
2019-02-13 21:07 ` Salman Qazi
2019-03-04 19:48 ` [PATCH RESENT] " Salman Qazi
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