Chanho Min c22397888f 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: 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>
2018-11-19 11:28:10 +01:00
2018-11-18 12:21:09 -08:00
2018-11-19 11:28:10 +01:00
2018-10-31 08:54:14 -07:00
2018-11-15 10:59:37 -06:00
2018-10-31 11:01:38 -07:00
2018-11-15 11:26:09 -06:00
2018-11-18 12:21:09 -08:00
2018-04-15 17:21:30 -07:00
2018-11-18 10:15:09 -08:00
2017-11-17 17:45:29 -08:00
2018-11-18 10:15:09 -08:00
2018-11-18 13:33:44 -08:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
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