From: Chanho Min chanho.min@lge.com
[ Upstream commit c22397888f1eed98cd59f0a88f2a5f6925f80e15 ]
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: Oleg Nesterov oleg@redhat.com Signed-off-by: Chanho Min chanho.min@lge.com Acked-by: Oleg Nesterov oleg@redhat.com Acked-by: Pavel Machek pavel@ucw.cz Acked-by: Michal Hocko mhocko@suse.com Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/exec.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/fs/exec.c b/fs/exec.c index 0da4d748b4e6..25c529f46aaa 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -62,6 +62,7 @@ #include <linux/oom.h> #include <linux/compat.h> #include <linux/vmalloc.h> +#include <linux/freezer.h>
#include <linux/uaccess.h> #include <asm/mmu_context.h> @@ -1079,7 +1080,7 @@ static int de_thread(struct task_struct *tsk) while (sig->notify_count) { __set_current_state(TASK_KILLABLE); spin_unlock_irq(lock); - schedule(); + freezable_schedule(); if (unlikely(__fatal_signal_pending(tsk))) goto killed; spin_lock_irq(lock); @@ -1107,7 +1108,7 @@ static int de_thread(struct task_struct *tsk) __set_current_state(TASK_KILLABLE); write_unlock_irq(&tasklist_lock); cgroup_threadgroup_change_end(tsk); - schedule(); + freezable_schedule(); if (unlikely(__fatal_signal_pending(tsk))) goto killed; }