On 07/19/2017 04:14 AM, Andrei Vagin wrote: > From: Andrei Vagin <ava...@virtuozzo.com> > > task_work_run() has to be called before exit_task_namespaces(), > because fuse_abort_conn() is called from __fput(). If it will not > be executed, we can hang in request_wait_answer(). We have seen this > situation when a process was the last member of a mount namespace > and the mount namespace has a vstorage fuse mount. >
Can we pleas have a changelog that doesn't look like an output of random text generator? The fact that "fuse_abort_conn() is called from __fput()" doesn't really explain why task_work_run() needs to be called before exit_task_namespaces. > https://jira.sw.ru/browse/PSBM-68266 > Signed-off-by: Andrei Vagin <ava...@virtuozzo.com> > --- > include/linux/task_work.h | 9 +++++++-- > kernel/exit.c | 9 +++++++++ > kernel/task_work.c | 4 ++-- > 3 files changed, 18 insertions(+), 4 deletions(-) > > diff --git a/include/linux/task_work.h b/include/linux/task_work.h > index ca5a1cf..b3af76d 100644 > --- a/include/linux/task_work.h > +++ b/include/linux/task_work.h > @@ -14,11 +14,16 @@ init_task_work(struct callback_head *twork, > task_work_func_t func) > > int task_work_add(struct task_struct *task, struct callback_head *twork, > bool); > struct callback_head *task_work_cancel(struct task_struct *, > task_work_func_t); > -void task_work_run(void); > +void __task_work_run(bool exiting); > + > +static inline void task_work_run(void) > +{ > + return __task_work_run(false); > +} > > static inline void exit_task_work(struct task_struct *task) > { > - task_work_run(); > + __task_work_run(true); > } > > #endif /* _LINUX_TASK_WORK_H */ > diff --git a/kernel/exit.c b/kernel/exit.c > index 3c83db2..ea54a73 100644 > --- a/kernel/exit.c > +++ b/kernel/exit.c > @@ -827,6 +827,15 @@ void do_exit(long code) > exit_fs(tsk); > if (group_dead) > disassociate_ctty(1); > + > + /* > + * task_work_run() has to be called before exit_task_namespaces(), > + * because fuse_abort_conn() is called from __fput(). If it will not > + * be executed, we can hang in request_wait_answer(). We have seen this > + * situation when a process was the last member of a mount namespace > + * and the mount namespace has a vstorage fuse mount. > + */ > + task_work_run(); Given that this is purely fuse's problem, maybe request_wait_answer() could just call task_work_run()? Or maybe we can just call exit_task_work(tsk) before exit_task_namespaces(tsk). This seems fine to me, but perhaps I'm missing something. > exit_task_namespaces(tsk); > exit_task_work(tsk); > > diff --git a/kernel/task_work.c b/kernel/task_work.c > index 65bd3c9..f0000c4 100644 > --- a/kernel/task_work.c > +++ b/kernel/task_work.c > @@ -46,7 +46,7 @@ task_work_cancel(struct task_struct *task, task_work_func_t > func) > return work; > } > > -void task_work_run(void) > +void __task_work_run(bool exiting) > { > struct task_struct *task = current; > struct callback_head *work, *head, *next; > @@ -58,7 +58,7 @@ void task_work_run(void) > */ > do { > work = ACCESS_ONCE(task->task_works); > - head = !work && (task->flags & PF_EXITING) ? > + head = !work && exiting ? Why we need this change? AFAIU this will allow to add more task_works in exit_task_namespaces() before final exit_task_work(). What's the point of this? > &work_exited : NULL; > } while (cmpxchg(&task->task_works, work, head) != work); > > _______________________________________________ Devel mailing list Devel@openvz.org https://lists.openvz.org/mailman/listinfo/devel
