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f5d39b0208
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Peter Zijlstra f5d39b0208 freezer,sched: Rewrite core freezer logic 
Rewrite the core freezer to behave better wrt thawing and be simpler
in general.

By replacing PF_FROZEN with TASK_FROZEN, a special block state, it is
ensured frozen tasks stay frozen until thawed and don't randomly wake
up early, as is currently possible.

As such, it does away with PF_FROZEN and PF_FREEZER_SKIP, freeing up
two PF_flags (yay!).

Specifically; the current scheme works a little like:

	freezer_do_not_count();
	schedule();
	freezer_count();

And either the task is blocked, or it lands in try_to_freezer()
through freezer_count(). Now, when it is blocked, the freezer
considers it frozen and continues.

However, on thawing, once pm_freezing is cleared, freezer_count()
stops working, and any random/spurious wakeup will let a task run
before its time.

That is, thawing tries to thaw things in explicit order; kernel
threads and workqueues before doing bringing SMP back before userspace
etc.. However due to the above mentioned races it is entirely possible
for userspace tasks to thaw (by accident) before SMP is back.

This can be a fatal problem in asymmetric ISA architectures (eg ARMv9)
where the userspace task requires a special CPU to run.

As said; replace this with a special task state TASK_FROZEN and add
the following state transitions:

	TASK_FREEZABLE	-> TASK_FROZEN
	__TASK_STOPPED	-> TASK_FROZEN
	__TASK_TRACED	-> TASK_FROZEN

The new TASK_FREEZABLE can be set on any state part of TASK_NORMAL
(IOW. TASK_INTERRUPTIBLE and TASK_UNINTERRUPTIBLE) -- any such state
is already required to deal with spurious wakeups and the freezer
causes one such when thawing the task (since the original state is
lost).

The special __TASK_{STOPPED,TRACED} states *can* be restored since
their canonical state is in ->jobctl.

With this, frozen tasks need an explicit TASK_FROZEN wakeup and are
free of undue (early / spurious) wakeups.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://lore.kernel.org/r/20220822114649.055452969@infradead.org
2022-09-07 21:53:50 +02:00
..
9p 9p: Fix some kernel-doc comments 2022-07-02 18:52:21 +09:00
adfs fs: Convert block_read_full_page() to block_read_full_folio() 2022-05-09 16:21:44 -04:00
affs affs: use memcpy_to_page and remove replace kmap_atomic() 2022-08-01 19:53:31 +02:00
afs AFS fixes 2022-08-09 10:08:08 -07:00
autofs autofs: remove unused ino field inode 2022-07-17 17:31:42 -07:00
befs befs: Convert befs_symlink_read_folio() to use a folio 2022-08-02 12:34:03 -04:00
bfs fs: Convert block_read_full_page() to block_read_full_folio() 2022-05-09 16:21:44 -04:00
btrfs - The usual batches of cleanups from Baoquan He, Muchun Song, Miaohe 2022-08-05 16:32:45 -07:00
cachefiles cachefiles: narrow the scope of flushed requests when releasing fd 2022-07-05 16:12:21 +01:00
ceph fs.setgid.v6.0 2022-08-09 09:52:28 -07:00
cifs freezer,sched: Rewrite core freezer logic 2022-09-07 21:53:50 +02:00
coda coda: Convert coda_symlink_filler() to use a folio 2022-08-02 12:34:03 -04:00
configfs configfs: fix a race in configfs_{,un}register_subsystem() 2022-02-22 18:30:28 +01:00
cramfs cramfs: read_mapping_page() is synchronous 2022-08-02 12:34:02 -04:00
crypto fscrypt: Add HCTR2 support for filename encryption 2022-06-10 16:40:18 +08:00
debugfs debugfs: Document that debugfs_create functions need not be error checked 2022-02-25 11:56:13 +01:00
devpts fsnotify: fix fsnotify hooks in pseudo filesystems 2022-01-24 14:17:02 +01:00
dlm fs: dlm: move kref_put assert for lkb structs 2022-08-01 09:31:46 -05:00
ecryptfs ecryptfs: Convert ecryptfs to read_folio 2022-05-09 16:21:45 -04:00
efivarfs efi: vars: Move efivar caching layer into efivarfs 2022-06-24 20:40:19 +02:00
efs efs: Convert efs symlinks to read_folio 2022-05-09 16:21:45 -04:00
erofs - The usual batches of cleanups from Baoquan He, Muchun Song, Miaohe 2022-08-05 16:32:45 -07:00
exfat exfat: Drop superfluous new line for error messages 2022-08-01 10:14:07 +09:00
exportfs exportfs: support idmapped mounts 2022-04-28 16:31:10 +02:00
ext2 - The usual batches of cleanups from Baoquan He, Muchun Song, Miaohe 2022-08-05 16:32:45 -07:00
ext4 - The usual batches of cleanups from Baoquan He, Muchun Song, Miaohe 2022-08-05 16:32:45 -07:00
f2fs f2fs-for-6.0 2022-08-08 11:18:31 -07:00
fat Updates to various subsystems which I help look after. lib, ocfs2, 2022-08-07 10:03:24 -07:00
freevxfs freevxfs: Convert vxfs_immed_read_folio() to use a folio 2022-08-02 12:34:03 -04:00
fscache fscache: add tracepoint when failing cookie 2022-08-09 14:13:59 +01:00
fuse iov_iter stuff, part 2, rebased 2022-08-08 20:04:35 -07:00
gfs2 iov_iter stuff, part 2, rebased 2022-08-08 20:04:35 -07:00
hfs hfs: Remove check for PageError 2022-06-29 08:51:06 -04:00
hfsplus Folio changes for 6.0 2022-08-03 10:35:43 -07:00
hostfs hostfs: Handle page write errors correctly 2022-08-02 12:34:02 -04:00
hpfs hpfs: Convert symlinks to read_folio 2022-05-09 16:21:45 -04:00
hugetlbfs iov_iter stuff, part 2, rebased 2022-08-08 20:04:35 -07:00
iomap new iov_iter flavour - ITER_UBUF 2022-08-08 22:37:15 -04:00
isofs fs/buffer: Combine two submit_bh() and ll_rw_block() arguments 2022-07-14 12:14:32 -06:00
jbd2 - The usual batches of cleanups from Baoquan He, Muchun Song, Miaohe 2022-08-05 16:32:45 -07:00
jffs2 This pull request contains fixes for JFFS2, UBI and UBIFS 2022-06-03 14:42:24 -07:00
jfs Folio changes for 6.0 2022-08-03 10:35:43 -07:00
kernfs kernfs: Fix typo 'the the' in comment 2022-07-28 10:57:25 +02:00
ksmbd 12 server fixes, including for oopses, memory leaks and adding a channel lock 2022-08-08 20:15:13 -07:00
lockd lockd: detect and reject lock arguments that overflow 2022-08-04 10:28:48 -04:00
minix fs: Convert block_read_full_page() to block_read_full_folio() 2022-05-09 16:21:44 -04:00
netfs netfs: do not unlock and put the folio twice 2022-07-14 10:10:12 +02:00
nfs freezer,sched: Rewrite core freezer logic 2022-09-07 21:53:50 +02:00
nfs_common
nfsd NFSD 6.0 Release Notes 2022-08-09 14:56:49 -07:00
nilfs2 Folio changes for 6.0 2022-08-03 10:35:43 -07:00
nls
notify fsnotify: Fix comment typo 2022-07-26 13:38:47 +02:00
ntfs Folio changes for 6.0 2022-08-03 10:35:43 -07:00
ntfs3 Folio changes for 6.0 2022-08-03 10:35:43 -07:00
ocfs2 fs.setgid.v6.0 2022-08-09 09:52:28 -07:00
omfs fs: Convert block_read_full_page() to block_read_full_folio() 2022-05-09 16:21:44 -04:00
openpromfs fs: allocate inode by using alloc_inode_sb() 2022-03-22 15:57:03 -07:00
orangefs orangefs: Remove test for folio error 2022-06-29 08:51:07 -04:00
overlayfs overlayfs update for 6.0 2022-08-08 11:03:11 -07:00
proc Updates to various subsystems which I help look after. lib, ocfs2, 2022-08-07 10:03:24 -07:00
pstore EFI updates for v5.20 2022-08-03 14:38:02 -07:00
qnx4 fs: Convert block_read_full_page() to block_read_full_folio() 2022-05-09 16:21:44 -04:00
qnx6 fs: Convert mpage_readpage to mpage_read_folio 2022-05-09 16:21:44 -04:00
quota - The usual batches of cleanups from Baoquan He, Muchun Song, Miaohe 2022-08-05 16:32:45 -07:00
ramfs
reiserfs Folio changes for 6.0 2022-08-03 10:35:43 -07:00
romfs romfs: Convert romfs to read_folio 2022-05-09 16:21:46 -04:00
smbfs_common Add various fsctl structs 2022-05-23 20:24:12 -05:00
squashfs Updates to various subsystems which I help look after. lib, ocfs2, 2022-08-07 10:03:24 -07:00
sysfs kobject: kobj_type: remove default_attrs 2022-04-05 15:39:19 +02:00
sysv Not a lot of material this cycle. Many singleton patches against various 2022-05-27 11:22:03 -07:00
tracefs tracefs: Fix syntax errors in comments 2022-06-17 19:01:28 -04:00
ubifs - The usual batches of cleanups from Baoquan He, Muchun Song, Miaohe 2022-08-05 16:32:45 -07:00
udf fs/buffer: Combine two submit_bh() and ll_rw_block() arguments 2022-07-14 12:14:32 -06:00
ufs Folio changes for 6.0 2022-08-03 10:35:43 -07:00
unicode kbuild: unify cmd_copy and cmd_shipped 2022-02-14 10:37:32 +09:00
vboxsf vboxsf: Convert vboxsf to read_folio 2022-05-09 16:21:46 -04:00
verity fs-verity: mention btrfs support 2022-07-15 23:42:30 -07:00
xfs freezer,sched: Rewrite core freezer logic 2022-09-07 21:53:50 +02:00
zonefs zonefs changes for 5.20-rc1 2022-08-03 15:21:53 -07:00
aio.c iov_iter work, part 1 - isolated cleanups and optimizations. 2022-08-03 13:50:22 -07:00
anon_inodes.c
attr.c vfs: Check the truncate maximum size in inode_newsize_ok() 2022-08-08 10:39:29 -07:00
bad_inode.c
binfmt_aout.c
binfmt_elf_fdpic.c coredump: Snapshot the vmas in do_coredump 2022-03-08 12:55:29 -06:00
binfmt_elf_test.c binfmt_elf: Introduce KUnit test 2022-03-03 20:38:56 -08:00
binfmt_elf.c revert "fs/binfmt_elf: use PT_LOAD p_align values for static PIE" 2022-04-15 14:49:56 -07:00
binfmt_flat.c binfmt_flat: Remove shared library support 2022-04-22 10:57:18 -07:00
binfmt_misc.c Fix regression due to "fs: move binfmt_misc sysctl to its own file" 2022-02-09 09:50:02 -08:00
binfmt_script.c
buffer.c Folio changes for 6.0 2022-08-03 10:35:43 -07:00
char_dev.c
compat_binfmt_elf.c binfmt_elf: Introduce KUnit test 2022-03-03 20:38:56 -08:00
coredump.c freezer,sched: Rewrite core freezer logic 2022-09-07 21:53:50 +02:00
d_path.c
dax.c - The usual batches of cleanups from Baoquan He, Muchun Song, Miaohe 2022-08-05 16:32:45 -07:00
dcache.c fs/dcache: Move wakeup out of i_seq_dir write held region. 2022-07-30 00:38:16 -04:00
direct-io.c iov_iter: advancing variants of iov_iter_get_pages{,_alloc}() 2022-08-08 22:37:22 -04:00
drop_caches.c
eventfd.c
eventpoll.c epoll: autoremove wakers even more aggressively 2022-07-17 17:31:40 -07:00
exec.c execve updates for v5.20-rc1 2022-08-02 14:36:19 -07:00
fcntl.c keep iocb_flags() result cached in struct file 2022-06-10 16:10:23 -04:00
fhandle.c
file_table.c iov_iter work, part 1 - isolated cleanups and optimizations. 2022-08-03 13:50:22 -07:00
file.c fix the breakage in close_fd_get_file() calling conventions change 2022-06-05 15:03:03 -04:00
filesystems.c
fs_context.c vfs: fs_context: fix up param length parsing in legacy_parse_param 2022-01-18 09:23:19 +02:00
fs_parser.c
fs_pin.c
fs_struct.c
fs_types.c
fs-writeback.c writeback: Fix inode->i_io_list not be protected by inode->i_lock error 2022-06-06 09:54:30 +02:00
fsopen.c uninline may_mount() and don't opencode it in fspick(2)/fsopen(2) 2022-05-19 23:25:10 -04:00
init.c
inode.c fs.setgid.v6.0 2022-08-09 09:52:28 -07:00
internal.h Cleanups (and one fix) around struct mount handling. 2022-06-04 19:00:05 -07:00
ioctl.c Fixes for 5.18-rc1: 2022-04-01 19:35:56 -07:00
Kconfig mm: hugetlb_vmemmap: introduce the name HVO 2022-08-08 18:06:42 -07:00
Kconfig.binfmt m68knommu: changes for linux 5.19 2022-05-30 10:56:18 -07:00
kernel_read_file.c fs/kernel_read_file: allow to read files up-to ssize_t 2022-06-16 19:58:21 -07:00
libfs.c fs: Convert simple_readpage to simple_read_folio 2022-05-09 16:21:44 -04:00
locks.c fs/lock: Rearrange ops in flock syscall. 2022-07-18 10:01:47 -04:00
Makefile io_uring: move to separate directory 2022-07-24 18:39:10 -06:00
mbcache.c - The usual batches of cleanups from Baoquan He, Muchun Song, Miaohe 2022-08-05 16:32:45 -07:00
mount.h switch try_to_unlazy_next() to __legitimize_mnt() 2022-07-05 16:18:21 -04:00
mpage.c Folio changes for 6.0 2022-08-03 10:35:43 -07:00
namei.c fs.setgid.v6.0 2022-08-09 09:52:28 -07:00
namespace.c switch try_to_unlazy_next() to __legitimize_mnt() 2022-07-05 16:18:21 -04:00
no-block.c
nsfs.c
open.c iov_iter work, part 1 - isolated cleanups and optimizations. 2022-08-03 13:50:22 -07:00
pipe.c Not a lot of material this cycle. Many singleton patches against various 2022-05-27 11:22:03 -07:00
pnode.c
pnode.h
posix_acl.c acl: make posix_acl_clone() available to overlayfs 2022-07-15 22:09:57 +02:00
proc_namespace.c
read_write.c switch new_sync_{read,write}() to ITER_UBUF 2022-08-08 22:37:15 -04:00
readdir.c
remap_range.c - The usual batches of cleanups from Baoquan He, Muchun Song, Miaohe 2022-08-05 16:32:45 -07:00
select.c select: Fix indefinitely sleeping task in poll_schedule_timeout() 2022-01-11 09:03:05 -08:00
seq_file.c rxrpc: Fix locking issue 2022-05-22 21:03:01 +01:00
signalfd.c Merge branch 'signal-for-v5.17' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2022-01-17 05:49:30 +02:00
splice.c iter_to_pipe(): switch to advancing variant of iov_iter_get_pages() 2022-08-08 22:37:23 -04:00
stack.c
stat.c RISC-V Patches for the 5.19 Merge Window, Part 1 2022-05-31 14:10:54 -07:00
statfs.c
super.c fuse update for 6.0 2022-08-08 11:10:02 -07:00
sync.c riscv: compat: syscall: Add compat_sys_call_table implementation 2022-04-26 13:36:25 -07:00
sysctls.c fs: move namespace sysctls and declare fs base directory 2022-01-22 08:33:36 +02:00
timerfd.c
userfaultfd.c - The usual batches of cleanups from Baoquan He, Muchun Song, Miaohe 2022-08-05 16:32:45 -07:00
utimes.c
xattr.c acl: move idmapped mount fixup into vfs_{g,s}etxattr() 2022-07-15 22:08:59 +02:00