Commit c2239788 authored by Chanho Min's avatar Chanho Min Committed by Rafael J. Wysocki

exec: make de_thread() freezable

Suspend fails due to the exec family of functions blocking the freezer.
The casue is that de_thread() sleeps in TASK_UNINTERRUPTIBLE waiting for
all sub-threads to die, and we have the deadlock if one of them is frozen.
This also can occur with the schedule() waiting for the group thread leader
to exit if it is frozen.

In our machine, it causes freeze timeout as bellows.

Freezing of tasks failed after 20.010 seconds (1 tasks refusing to freeze, wq_busy=0):
setcpushares-ls D ffffffc00008ed70     0  5817   1483 0x0040000d
 Call trace:
[<ffffffc00008ed70>] __switch_to+0x88/0xa0
[<ffffffc000d1c30c>] __schedule+0x1bc/0x720
[<ffffffc000d1ca90>] schedule+0x40/0xa8
[<ffffffc0001cd784>] flush_old_exec+0xdc/0x640
[<ffffffc000220360>] load_elf_binary+0x2a8/0x1090
[<ffffffc0001ccff4>] search_binary_handler+0x9c/0x240
[<ffffffc00021c584>] load_script+0x20c/0x228
[<ffffffc0001ccff4>] search_binary_handler+0x9c/0x240
[<ffffffc0001ce8e0>] do_execveat_common.isra.14+0x4f8/0x6e8
[<ffffffc0001cedd0>] compat_SyS_execve+0x38/0x48
[<ffffffc00008de30>] el0_svc_naked+0x24/0x28

To fix this, make de_thread() freezable. It looks safe and works fine.
Suggested-by: default avatarOleg Nesterov <oleg@redhat.com>
Signed-off-by: default avatarChanho Min <chanho.min@lge.com>
Acked-by: default avatarOleg Nesterov <oleg@redhat.com>
Acked-by: default avatarPavel Machek <pavel@ucw.cz>
Acked-by: default avatarMichal Hocko <mhocko@suse.com>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent 9ff01193
...@@ -62,6 +62,7 @@ ...@@ -62,6 +62,7 @@
#include <linux/oom.h> #include <linux/oom.h>
#include <linux/compat.h> #include <linux/compat.h>
#include <linux/vmalloc.h> #include <linux/vmalloc.h>
#include <linux/freezer.h>
#include <linux/uaccess.h> #include <linux/uaccess.h>
#include <asm/mmu_context.h> #include <asm/mmu_context.h>
...@@ -1083,7 +1084,7 @@ static int de_thread(struct task_struct *tsk) ...@@ -1083,7 +1084,7 @@ static int de_thread(struct task_struct *tsk)
while (sig->notify_count) { while (sig->notify_count) {
__set_current_state(TASK_KILLABLE); __set_current_state(TASK_KILLABLE);
spin_unlock_irq(lock); spin_unlock_irq(lock);
schedule(); freezable_schedule();
if (unlikely(__fatal_signal_pending(tsk))) if (unlikely(__fatal_signal_pending(tsk)))
goto killed; goto killed;
spin_lock_irq(lock); spin_lock_irq(lock);
...@@ -1111,7 +1112,7 @@ static int de_thread(struct task_struct *tsk) ...@@ -1111,7 +1112,7 @@ static int de_thread(struct task_struct *tsk)
__set_current_state(TASK_KILLABLE); __set_current_state(TASK_KILLABLE);
write_unlock_irq(&tasklist_lock); write_unlock_irq(&tasklist_lock);
cgroup_threadgroup_change_end(tsk); cgroup_threadgroup_change_end(tsk);
schedule(); freezable_schedule();
if (unlikely(__fatal_signal_pending(tsk))) if (unlikely(__fatal_signal_pending(tsk)))
goto killed; goto killed;
} }
......
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