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linux/mm
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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
..
damon - The usual batches of cleanups from Baoquan He, Muchun Song, Miaohe 2022-08-05 16:32:45 -07:00
kasan - The usual batches of cleanups from Baoquan He, Muchun Song, Miaohe 2022-08-05 16:32:45 -07:00
kfence - The usual batches of cleanups from Baoquan He, Muchun Song, Miaohe 2022-08-05 16:32:45 -07:00
backing-dev.c init: Initialize noop_backing_dev_info early 2022-06-16 10:55:57 +02:00
balloon_compaction.c mm: Convert all PageMovable users to movable_operations 2022-08-02 12:34:03 -04:00
bootmem_info.c
cma_debug.c mm/cma_debug.c: align the name buffer length as struct cma 2022-07-29 18:07:16 -07:00
cma_sysfs.c
cma.c Revert "mm/cma.c: remove redundant cma_mutex lock" 2022-05-13 15:11:26 -07:00
cma.h mm/cma: provide option to opt out from exposing pages on activation failure 2022-03-22 15:57:09 -07:00
compaction.c - The usual batches of cleanups from Baoquan He, Muchun Song, Miaohe 2022-08-05 16:32:45 -07:00
debug_page_ref.c
debug_vm_pgtable.c docs: rename Documentation/vm to Documentation/mm 2022-06-27 12:52:53 -07:00
debug.c mm: unexport page_init_poison 2022-03-24 19:06:45 -07:00
dmapool.c mm/dmapool.c: revert "make dma pool to use kmalloc_node" 2022-01-15 16:30:28 +02:00
early_ioremap.c mm/early_ioremap: declare early_memremap_pgprot_adjust() 2022-03-22 15:57:11 -07:00
fadvise.c riscv: compat: syscall: Add compat_sys_call_table implementation 2022-04-26 13:36:25 -07:00
failslab.c mm: fix missing handler for __GFP_NOWARN 2022-05-19 14:08:55 -07:00
filemap.c - The usual batches of cleanups from Baoquan He, Muchun Song, Miaohe 2022-08-05 16:32:45 -07:00
folio-compat.c mm/folio-compat: Remove migration compatibility functions 2022-08-02 12:34:04 -04:00
frontswap.c docs: rename Documentation/vm to Documentation/mm 2022-06-27 12:52:53 -07:00
gup_test.c mm: rename is_pinnable_page() to is_longterm_pinnable_page() 2022-07-17 17:14:27 -07:00
gup_test.h
gup.c - The usual batches of cleanups from Baoquan He, Muchun Song, Miaohe 2022-08-05 16:32:45 -07:00
highmem.c - The usual batches of cleanups from Baoquan He, Muchun Song, Miaohe 2022-08-05 16:32:45 -07:00
hmm.c mm/hmm: fault non-owner device private entries 2022-07-29 11:33:37 -07:00
huge_memory.c - The usual batches of cleanups from Baoquan He, Muchun Song, Miaohe 2022-08-05 16:32:45 -07:00
hugetlb_cgroup.c hugetlb_cgroup: fix wrong hugetlb cgroup numa stat 2022-07-29 18:07:17 -07:00
hugetlb_vmemmap.c mm: hugetlb_vmemmap: use PTRS_PER_PTE instead of PMD_SIZE / PAGE_SIZE 2022-08-08 18:06:43 -07:00
hugetlb_vmemmap.h mm: hugetlb_vmemmap: improve hugetlb_vmemmap code readability 2022-08-08 18:06:43 -07:00
hugetlb.c mm, hwpoison, hugetlb: support saving mechanism of raw error pages 2022-08-08 18:06:44 -07:00
hwpoison-inject.c mm/memory-failure: disable unpoison once hw error happens 2022-06-16 19:11:32 -07:00
init-mm.c kernel/fork: Initialize mm's PASID 2022-02-14 19:51:47 +01:00
internal.h - The usual batches of cleanups from Baoquan He, Muchun Song, Miaohe 2022-08-05 16:32:45 -07:00
interval_tree.c
io-mapping.c
ioremap.c mm: ioremap: Add ioremap/iounmap_allowed() 2022-06-27 12:22:31 +01:00
Kconfig cxl for 6.0 2022-08-10 11:07:26 -07:00
Kconfig.debug Two followon fixes for the post-5.19 series "Use pageblock_order for cma 2022-05-27 11:40:49 -07:00
khugepaged.c freezer,sched: Rewrite core freezer logic 2022-09-07 21:53:50 +02:00
kmemleak.c mm/kmemleak: prevent soft lockup in first object iteration loop of kmemleak_scan() 2022-06-16 19:48:32 -07:00
ksm.c - The usual batches of cleanups from Baoquan He, Muchun Song, Miaohe 2022-08-05 16:32:45 -07:00
list_lru.c mm: kmem: make mem_cgroup_from_obj() vmalloc()-safe 2022-06-16 19:48:31 -07:00
maccess.c asm-generic updates for 5.18 2022-03-23 18:03:08 -07:00
madvise.c mm: handling Non-LRU pages returned by vm_normal_pages 2022-07-17 17:14:28 -07:00
Makefile mm: shrinkers: introduce debugfs interface for memory shrinkers 2022-07-03 18:08:40 -07:00
mapping_dirty_helpers.c
memblock.c memblock updates for v5.20 2022-08-09 09:48:30 -07:00
memcontrol.c mm: memcontrol: fix potential oom_lock recursion deadlock 2022-07-29 18:07:18 -07:00
memfd.c memfd: fix F_SEAL_WRITE after shmem huge page allocated 2022-03-05 11:08:32 -08:00
memory_hotplug.c mm: use is_zone_movable_page() helper 2022-07-29 18:07:20 -07:00
memory-failure.c mm, hwpoison: enable memory error handling on 1GB hugepage 2022-08-08 18:06:44 -07:00
memory.c - The usual batches of cleanups from Baoquan He, Muchun Song, Miaohe 2022-08-05 16:32:45 -07:00
mempolicy.c mm/mempolicy: remove unneeded out label 2022-07-29 18:07:16 -07:00
mempool.c mm/mempool: use might_alloc() 2022-06-16 19:48:30 -07:00
memremap.c - The usual batches of cleanups from Baoquan He, Muchun Song, Miaohe 2022-08-05 16:32:45 -07:00
memtest.c
migrate_device.c - The usual batches of cleanups from Baoquan He, Muchun Song, Miaohe 2022-08-05 16:32:45 -07:00
migrate.c - The usual batches of cleanups from Baoquan He, Muchun Song, Miaohe 2022-08-05 16:32:45 -07:00
mincore.c mm: teach core mm about pte markers 2022-05-13 07:20:09 -07:00
mlock.c mm: handling Non-LRU pages returned by vm_normal_pages 2022-07-17 17:14:28 -07:00
mm_init.c
mmap_lock.c
mmap.c mm/mprotect: fix soft-dirty check in can_change_pte_writable() 2022-07-29 18:07:18 -07:00
mmu_gather.c mm/mmu_gather: limit free batch count and add schedule point in tlb_batch_pages_flush 2022-04-28 23:16:12 -07:00
mmu_notifier.c mm/mmu_notifier.c: fix race in mmu_interval_notifier_remove() 2022-04-21 20:01:10 -07:00
mmzone.c Folio changes for 5.18 2022-03-22 17:03:12 -07:00
mprotect.c mm/mprotect: fix soft-dirty check in can_change_pte_writable() 2022-07-29 18:07:18 -07:00
mremap.c Yang Shi has improved the behaviour of khugepaged collapsing of readonly 2022-05-26 12:32:41 -07:00
msync.c
nommu.c mm: nommu: pass a pointer to virt_to_page() 2022-07-17 17:14:37 -07:00
oom_kill.c mm/oom_kill.c: fix vm_oom_kill_table[] ifdeffery 2022-06-01 15:57:16 -07:00
page_alloc.c - The usual batches of cleanups from Baoquan He, Muchun Song, Miaohe 2022-08-05 16:32:45 -07:00
page_counter.c
page_ext.c mm: use for_each_online_node and node_online instead of open coding 2022-04-29 14:36:58 -07:00
page_idle.c mm: don't be stuck to rmap lock on reclaim path 2022-05-19 14:08:54 -07:00
page_io.c Yang Shi has improved the behaviour of khugepaged collapsing of readonly 2022-05-26 12:32:41 -07:00
page_isolation.c mm/page_isolation.c: fix one kernel-doc comment 2022-06-16 19:11:30 -07:00
page_owner.c Yang Shi has improved the behaviour of khugepaged collapsing of readonly 2022-05-26 12:32:41 -07:00
page_poison.c
page_reporting.c
page_reporting.h
page_table_check.c Six hotfixes. One from Miaohe Lin is considered a minor thing so it isn't 2022-05-27 11:29:35 -07:00
page_vma_mapped.c mm/page_vma_mapped.c: use helper function huge_pte_lock 2022-07-17 17:14:47 -07:00
page-writeback.c mm: Add balance_dirty_pages_ratelimited_flags() function 2022-07-24 18:39:31 -06:00
pagewalk.c
percpu-internal.h percpu: improve percpu_alloc_percpu event trace 2022-05-13 07:20:18 -07:00
percpu-km.c
percpu-stats.c mm: use vmalloc_array and vcalloc for array allocations 2022-03-08 09:30:46 -05:00
percpu-vm.c
percpu.c mm: percpu: use kmemleak_ignore_phys() instead of kmemleak_free() 2022-07-17 17:14:47 -07:00
pgalloc-track.h
pgtable-generic.c mm: avoid unnecessary flush on change_huge_pmd() 2022-05-13 07:20:05 -07:00
process_vm_access.c
ptdump.c mm: sparsemem: use page table lock to protect kernel pmd operations 2022-03-22 15:57:08 -07:00
readahead.c filemap: Fix serialization adding transparent huge pages to page cache 2022-06-23 12:22:00 -04:00
rmap.c - The usual batches of cleanups from Baoquan He, Muchun Song, Miaohe 2022-08-05 16:32:45 -07:00
rodata_test.c
secretmem.c Folio changes for 6.0 2022-08-03 10:35:43 -07:00
shmem.c iov_iter stuff, part 2, rebased 2022-08-08 20:04:35 -07:00
shrinker_debug.c mm: shrinkers: fix double kfree on shrinker name 2022-07-29 18:07:13 -07:00
shuffle.c
shuffle.h
slab_common.c mm/slab_common: move generic bulk alloc/free functions to SLOB 2022-07-20 13:30:12 +02:00
slab.c - The usual batches of cleanups from Baoquan He, Muchun Song, Miaohe 2022-08-05 16:32:45 -07:00
slab.h mm/slab_common: move generic bulk alloc/free functions to SLOB 2022-07-20 13:30:12 +02:00
slob.c mm/slab_common: move generic bulk alloc/free functions to SLOB 2022-07-20 13:30:12 +02:00
slub.c mm/sl[au]b: use own bulk free function when bulk alloc failed 2022-07-20 13:30:11 +02:00
sparse-vmemmap.c mm: hugetlb_vmemmap: move vmemmap code related to HugeTLB to hugetlb_vmemmap.c 2022-08-08 18:06:42 -07:00
sparse.c mm: memory_hotplug: enumerate all supported section flags 2022-07-03 18:08:49 -07:00
swap_cgroup.c mm: use vmalloc_array and vcalloc for array allocations 2022-03-08 09:30:46 -05:00
swap_slots.c arm64: enable THP_SWAP for arm64 2022-07-20 10:52:40 +01:00
swap_state.c - The usual batches of cleanups from Baoquan He, Muchun Song, Miaohe 2022-08-05 16:32:45 -07:00
swap.c - The usual batches of cleanups from Baoquan He, Muchun Song, Miaohe 2022-08-05 16:32:45 -07:00
swap.h mm/khugepaged: try to free transhuge swapcache when possible 2022-07-03 18:08:52 -07:00
swapfile.c mm/swap: convert delete_from_swap_cache() to take a folio 2022-07-03 18:08:48 -07:00
truncate.c mm: Remove __delete_from_page_cache() 2022-06-29 08:51:05 -04:00
usercopy.c usercopy: use unsigned long instead of uintptr_t 2022-07-01 17:03:38 -07:00
userfaultfd.c mm: userfaultfd: fix UFFDIO_CONTINUE on fallocated shmem pages 2022-07-03 15:42:32 -07:00
util.c - The usual batches of cleanups from Baoquan He, Muchun Song, Miaohe 2022-08-05 16:32:45 -07:00
vmacache.c
vmalloc.c mm/vmalloc: extend __find_vmap_area() with one more argument 2022-07-03 18:08:41 -07:00
vmpressure.c
vmscan.c - The usual batches of cleanups from Baoquan He, Muchun Song, Miaohe 2022-08-05 16:32:45 -07:00
vmstat.c Bitmap patches for 5.19-rc1 2022-06-04 14:04:27 -07:00
workingset.c mm: shrinkers: provide shrinkers with names 2022-07-03 18:08:40 -07:00
z3fold.c mm: Convert all PageMovable users to movable_operations 2022-08-02 12:34:03 -04:00
zbud.c
zpool.c zpool: remove the list of pools_head 2022-01-15 16:30:31 +02:00
zsmalloc.c - The usual batches of cleanups from Baoquan He, Muchun Song, Miaohe 2022-08-05 16:32:45 -07:00
zswap.c zswap: memcg accounting 2022-05-19 14:08:53 -07:00