AcoSail/kernel_optimize_test
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kernel_optimize_test/mm
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Linus Torvalds 1ac5cd4978 block: don't use un-ordered __set_current_state(TASK_UNINTERRUPTIBLE) 
This mostly reverts commit 849a370016 ("block: avoid ordered task
state change for polled IO").  It was wrongly claiming that the ordering
wasn't necessary.  The memory barrier _is_ necessary.

If something is truly polling and not going to sleep, it's the whole
state setting that is unnecessary, not the memory barrier.  Whenever you
set your state to a sleeping state, you absolutely need the memory
barrier.

Note that sometimes the memory barrier can be elsewhere.  For example,
the ordering might be provided by an external lock, or by setting the
process state to sleeping before adding yourself to the wait queue list
that is used for waking up (where the wait queue lock itself will
guarantee that any wakeup will correctly see the sleeping state).

But none of those cases were true here.

NOTE! Some of the polling paths may indeed be able to drop the state
setting entirely, at which point the memory barrier also goes away.

(Also note that this doesn't revert the TASK_RUNNING cases: there is no
race between a wakeup and setting the process state to TASK_RUNNING,
since the end result doesn't depend on ordering).

Cc: Jens Axboe <axboe@kernel.dk>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-01-02 10:46:03 -08:00
..
kasan mm: convert totalram_pages and totalhigh_pages variables to atomic 2018-12-28 12:11:47 -08:00
backing-dev.c blkcg: delay blkg destruction until after writeback has finished 2018-08-31 14:48:56 -06:00
balloon_compaction.c
cleancache.c
cma_debug.c
cma.c kasan, mm, arm64: tag non slab memory allocated via pagealloc 2018-12-28 12:11:44 -08:00
cma.h
compaction.c mm: move zone watermark accesses behind an accessor 2018-12-28 12:11:48 -08:00
debug_page_ref.c
debug.c mm/debug.c: make "migrate_reason_names[]" const char * 2018-12-28 12:11:48 -08:00
dmapool.c
early_ioremap.c
fadvise.c vfs: implement readahead(2) using POSIX_FADV_WILLNEED 2018-08-30 20:01:32 +02:00
failslab.c
filemap.c mm, fault_around: do not take a reference to a locked page 2018-12-28 12:11:51 -08:00
frame_vector.c
frontswap.c
gup_benchmark.c mm/gup_benchmark.c: prevent integer overflow in ioctl 2018-10-31 08:54:12 -07:00
gup.c mm/gup: finish consolidating error handling 2018-11-30 14:56:13 -08:00
highmem.c mm: convert totalram_pages and totalhigh_pages variables to atomic 2018-12-28 12:11:47 -08:00
hmm.c mm/hmm: fix memremap.h, move dev_page_fault_t callback to hmm 2018-12-28 12:11:52 -08:00
huge_memory.c mm, thp, proc: report THP eligibility for each vma 2018-12-28 12:11:50 -08:00
hugetlb_cgroup.c
hugetlb.c hugetlbfs: Use i_mmap_rwsem to fix page fault/truncate race 2018-12-28 12:11:52 -08:00
hwpoison-inject.c
init-mm.c
internal.h mm: use alloc_flags to record if kswapd can wake 2018-12-28 12:11:48 -08:00
interval_tree.c
Kconfig ksm: replace jhash2 with xxhash 2018-12-28 12:11:46 -08:00
Kconfig.debug
khugepaged.c mm/mmu_notifier: use structure for invalidate_range_start/end calls v2 2018-12-28 12:11:50 -08:00
kmemleak-test.c
kmemleak.c kmemleak: add config to select auto scan 2018-12-28 12:11:51 -08:00
ksm.c ksm: react on changing "sleep_millisecs" parameter faster 2018-12-28 12:11:51 -08:00
list_lru.c
maccess.c x86/fault: BUG() when uaccess helpers fault on kernel addresses 2018-09-03 15:12:09 +02:00
madvise.c mm/mmu_notifier: use structure for invalidate_range_start/end calls v2 2018-12-28 12:11:50 -08:00
Makefile mm: remove nobootmem 2018-10-31 08:54:16 -07:00
memblock.c mm/memblock.c: skip kmemleak for kasan_init() 2018-12-28 12:11:49 -08:00
memcontrol.c memcg, oom: notify on oom killer invocation from the charge path 2018-12-28 12:11:52 -08:00
memfd.c memfd: Convert memfd_tag_pins to XArray 2018-10-21 10:46:41 -04:00
memory_hotplug.c mm, memory_hotplug: deobfuscate migration part of offlining 2018-12-28 12:11:50 -08:00
memory-failure.c hugetlbfs: use i_mmap_rwsem for more pmd sharing synchronization 2018-12-28 12:11:51 -08:00
memory.c mm, thp, proc: report THP eligibility for each vma 2018-12-28 12:11:50 -08:00
mempolicy.c Revert "mm, thp: consolidate THP gfp handling into alloc_hugepage_direct_gfpmask" 2018-12-08 10:26:20 -08:00
mempool.c
memtest.c
migrate.c hugetlbfs: use i_mmap_rwsem for more pmd sharing synchronization 2018-12-28 12:11:51 -08:00
mincore.c xarray: Replace exceptional entries 2018-09-29 22:47:49 -04:00
mlock.c
mm_init.c mm: convert totalram_pages and totalhigh_pages variables to atomic 2018-12-28 12:11:47 -08:00
mmap.c mm/mmap.c: remove verify_mm_writelocked() 2018-12-28 12:11:47 -08:00
mmu_context.c
mmu_gather.c mm: Replace call_rcu_sched() with call_rcu() 2018-11-27 09:21:46 -08:00
mmu_notifier.c mm/mmu_notifier: use structure for invalidate_range_start/end calls v2 2018-12-28 12:11:50 -08:00
mmzone.c
mprotect.c mm/mmu_notifier: use structure for invalidate_range_start/end calls v2 2018-12-28 12:11:50 -08:00
mremap.c mm/mmu_notifier: use structure for invalidate_range_start/end calls v2 2018-12-28 12:11:50 -08:00
msync.c
nommu.c mm/gup: cache dev_pagemap while pinning pages 2018-10-26 16:38:15 -07:00
oom_kill.c mm/mmu_notifier: use structure for invalidate_range_start/end calls v2 2018-12-28 12:11:50 -08:00
page_alloc.c mm/page_alloc.c: allow error injection 2018-12-28 12:11:51 -08:00
page_counter.c
page_ext.c mm: remove include/linux/bootmem.h 2018-10-31 08:54:16 -07:00
page_idle.c mm: remove include/linux/bootmem.h 2018-10-31 08:54:16 -07:00
page_io.c block: don't use un-ordered __set_current_state(TASK_UNINTERRUPTIBLE) 2019-01-02 10:46:03 -08:00
page_isolation.c mm: only report isolation failures when offlining memory 2018-12-28 12:11:46 -08:00
page_owner.c mm/page_owner: clamp read count to PAGE_SIZE 2018-12-28 12:11:46 -08:00
page_poison.c virtio, vhost: fixes, tweaks 2018-11-01 14:42:49 -07:00
page_vma_mapped.c mm/rmap: map_pte() was not handling private ZONE_DEVICE page properly 2018-10-31 08:54:11 -07:00
page-writeback.c mm/page-writeback.c: don't break integrity writeback on ->writepage() error 2018-12-28 12:11:49 -08:00
pagewalk.c
percpu-internal.h
percpu-km.c percpu: convert spin_lock_irq to spin_lock_irqsave. 2018-12-18 09:04:08 -08:00
percpu-stats.c
percpu-vm.c
percpu.c Merge branch 'for-4.20' of git://git.kernel.org/pub/scm/linux/kernel/git/dennis/percpu 2018-11-01 09:27:57 -07:00
pgtable-generic.c x86/mm: Page size aware flush_tlb_mm_range() 2018-10-09 16:51:11 +02:00
process_vm_access.c
quicklist.c
readahead.c mm/readahead.c: simplify get_next_ra_size() 2018-12-28 12:11:46 -08:00
rmap.c hugetlbfs: use i_mmap_rwsem for more pmd sharing synchronization 2018-12-28 12:11:51 -08:00
rodata_test.c
shmem.c mm: convert totalram_pages and totalhigh_pages variables to atomic 2018-12-28 12:11:47 -08:00
slab_common.c A fairly normal cycle for documentation stuff. We have a new 2018-12-29 11:21:49 -08:00
slab.c mm: convert totalram_pages and totalhigh_pages variables to atomic 2018-12-28 12:11:47 -08:00
slab.h kasan, mm: change hooks signatures 2018-12-28 12:11:43 -08:00
slob.c
slub.c mm/slub.c: record final state of slub action in deactivate_slab() 2018-12-28 12:11:46 -08:00
sparse-vmemmap.c mm: remove include/linux/bootmem.h 2018-10-31 08:54:16 -07:00
sparse.c mm, sparse: pass nid instead of pgdat to sparse_add_one_section() 2018-12-28 12:11:49 -08:00
swap_cgroup.c
swap_slots.c
swap_state.c Merge branch 'xarray' of git://git.infradead.org/users/willy/linux-dax 2018-10-28 11:35:40 -07:00
swap.c mm: convert totalram_pages and totalhigh_pages variables to atomic 2018-12-28 12:11:47 -08:00
swapfile.c mm, swap: fix swapoff with KSM pages 2018-12-28 12:11:52 -08:00
truncate.c mm: cleancache: fix corruption on missed inode invalidation 2018-11-30 14:56:14 -08:00
usercopy.c
userfaultfd.c hugetlbfs: use i_mmap_rwsem for more pmd sharing synchronization 2018-12-28 12:11:51 -08:00
util.c mm: convert totalram_pages and totalhigh_pages variables to atomic 2018-12-28 12:11:47 -08:00
vmacache.c mm: get rid of vmacache_flush_all() entirely 2018-09-13 15:18:04 -10:00
vmalloc.c mm: convert totalram_pages and totalhigh_pages variables to atomic 2018-12-28 12:11:47 -08:00
vmpressure.c
vmscan.c mm: put_and_wait_on_page_locked() while page is migrated 2018-12-28 12:11:48 -08:00
vmstat.c mm: convert zone->managed_pages to atomic variable 2018-12-28 12:11:47 -08:00
workingset.c mm: convert totalram_pages and totalhigh_pages variables to atomic 2018-12-28 12:11:47 -08:00
z3fold.c z3fold: fix possible reclaim races 2018-11-18 10:15:09 -08:00
zbud.c
zpool.c
zsmalloc.c mm/zsmalloc.c: fix fall-through annotation 2018-10-26 16:26:35 -07:00
zswap.c mm: convert totalram_pages and totalhigh_pages variables to atomic 2018-12-28 12:11:47 -08:00