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mainlining shenanigans

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Rafael J. Wysocki a72173ecfc Revert "exec: make de_thread() freezable" Revert commit `c22397888f` "exec: make de_thread() freezable" as requested by Ingo Molnar: "So there's a new regression in v4.20-rc4, my desktop produces this lockdep splat: [ 1772.588771] WARNING: pkexec/4633 still has locks held! [ 1772.588773] 4.20.0-rc4-custom-00213-g93a49841322b #1 Not tainted [ 1772.588775] ------------------------------------ [ 1772.588776] 1 lock held by pkexec/4633: [ 1772.588778] #0: 00000000ed85fbf8 (&sig->cred_guard_mutex){+.+.}, at: prepare_bprm_creds+0x2a/0x70 [ 1772.588786] stack backtrace: [ 1772.588789] CPU: 7 PID: 4633 Comm: pkexec Not tainted 4.20.0-rc4-custom-00213-g93a49841322b #1 [ 1772.588792] Call Trace: [ 1772.588800] dump_stack+0x85/0xcb [ 1772.588803] flush_old_exec+0x116/0x890 [ 1772.588807] ? load_elf_phdrs+0x72/0xb0 [ 1772.588809] load_elf_binary+0x291/0x1620 [ 1772.588815] ? sched_clock+0x5/0x10 [ 1772.588817] ? search_binary_handler+0x6d/0x240 [ 1772.588820] search_binary_handler+0x80/0x240 [ 1772.588823] load_script+0x201/0x220 [ 1772.588825] search_binary_handler+0x80/0x240 [ 1772.588828] __do_execve_file.isra.32+0x7d2/0xa60 [ 1772.588832] ? strncpy_from_user+0x40/0x180 [ 1772.588835] __x64_sys_execve+0x34/0x40 [ 1772.588838] do_syscall_64+0x60/0x1c0 The warning gets triggered by an ancient lockdep check in the freezer: (gdb) list 0xffffffff812ece06 0xffffffff812ece06 is in flush_old_exec (./include/linux/freezer.h:57). 52 DO NOT ADD ANY NEW CALLERS OF THIS FUNCTION 53 * If try_to_freeze causes a lockdep warning it means the caller may deadlock 54 */ 55 static inline bool try_to_freeze_unsafe(void) 56 { 57 might_sleep(); 58 if (likely(!freezing(current))) 59 return false; 60 return __refrigerator(false); 61 } I reviewed the ->cred_guard_mutex code, and the mutex is held across all of exec() - and we always did this. But there's this recent -rc4 commit: > Chanho Min (1): > exec: make de_thread() freezable `c22397888f`: exec: make de_thread() freezable I believe this commit is bogus, you cannot call try_to_freeze() from de_thread(), because it's holding the ->cred_guard_mutex." Reported-by: Ingo Molnar <mingo@kernel.org> Tested-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>		2018-12-04 16:04:20 +01:00
arch	ARM: SoC fixes	2018-12-02 12:19:44 -08:00
block	block: fix single range discard merge	2018-11-30 10:07:57 -07:00
certs	export.h: remove VMLINUX_SYMBOL() and VMLINUX_SYMBOL_STR()	2018-08-22 23:21:44 +09:00
crypto	crypto: user - Zeroize whole structure given to user space	2018-11-09 17:35:43 +08:00
Documentation	Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2018-12-01 12:35:48 -08:00
drivers	ARM: SoC fixes	2018-12-02 12:19:44 -08:00
firmware	kbuild: remove all dummy assignments to obj-	2017-11-18 11:46:06 +09:00
fs	Revert "exec: make de_thread() freezable"	2018-12-04 16:04:20 +01:00
include	ARM: SoC fixes	2018-12-02 12:19:44 -08:00
init	initramfs: clean old path before creating a hardlink	2018-11-30 14:56:14 -08:00
ipc	ipc: IPCMNI limit check for semmni	2018-10-31 08:54:14 -07:00
kernel	Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2018-12-01 12:35:48 -08:00
lib	debugobjects: avoid recursive calls with kmemleak	2018-11-30 14:56:14 -08:00
LICENSES	This is a fairly typical cycle for documentation. There's some welcome	2018-10-24 18:01:11 +01:00
mm	mm/khugepaged: fix the xas_create_range() error path	2018-11-30 14:56:15 -08:00
net	Merge git://git.kernel.org/pub/scm/linux/kernel/git/pablo/nf	2018-11-28 11:02:45 -08:00
samples	VFIO updates for v4.20	2018-10-31 11:01:38 -07:00
scripts	Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2018-12-01 12:35:48 -08:00
security	selinux/stable-4.20 PR 20181129	2018-11-29 10:15:06 -08:00
sound	ALSA: usb-audio: Add vendor and product name for Dell WD19 Dock	2018-11-28 10:59:49 +01:00
tools	Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2018-12-01 12:35:48 -08:00
usr	initramfs: move gen_initramfs_list.sh from scripts/ to usr/	2018-08-22 23:21:44 +09:00
virt	Revert "mm, mmu_notifier: annotate mmu notifiers with blockable invalidate callbacks"	2018-10-26 16:25:19 -07:00
.clang-format	page cache: Convert find_get_pages_contig to XArray	2018-10-21 10:46:34 -04:00
.cocciconfig	scripts: add Linux .cocciconfig for coccinelle	2016-07-22 12:13:39 +02:00
.get_maintainer.ignore
.gitattributes	.gitattributes: set git diff driver for C source code files	2016-10-07 18:46:30 -07:00
.gitignore	Kbuild updates for v4.17 (2nd)	2018-04-15 17:21:30 -07:00
.mailmap	mailmap: Update email for Punit Agrawal	2018-11-05 10:02:11 +00:00
COPYING	COPYING: use the new text with points to the license files	2018-03-23 12:41:45 -06:00
CREDITS	MAINTAINERS: change Sparse's maintainer	2018-11-25 09:17:43 -08:00
Kbuild	Kbuild updates for v4.15	2017-11-17 17:45:29 -08:00
Kconfig	kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt	2018-08-02 08:06:55 +09:00
MAINTAINERS	ARM: SoC fixes	2018-12-02 12:19:44 -08:00
Makefile	Linux 4.20-rc5	2018-12-02 15:07:55 -08:00
README	Drop all 00-INDEX files from Documentation/	2018-09-09 15:08:58 -06:00

README

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.