linux-stable.git/kernel/sched/core.c, branch v6.1.2 Linux kernel stable tree sched/uclamp: Fix fits_capacity() check in feec() 2022-12-31T12:31:54+00:00 Qais Yousef qais.yousef@arm.com 2022-08-04T14:36:03+00:00 75ba48621b33c072d26a6635a32842f8b6ab3338 [ Upstream commit 244226035a1f9b2b6c326e55ae5188fab4f428cb ] As reported by Yun Hsiang [1], if a task has its uclamp_min >= 0.8 * 1024, it'll always pick the previous CPU because fits_capacity() will always return false in this case. The new util_fits_cpu() logic should handle this correctly for us beside more corner cases where similar failures could occur, like when using UCLAMP_MAX. We open code uclamp_rq_util_with() except for the clamp() part, util_fits_cpu() needs the 'raw' values to be passed to it. Also introduce uclamp_rq_{set, get}() shorthand accessors to get uclamp value for the rq. Makes the code more readable and ensures the right rules (use READ_ONCE/WRITE_ONCE) are respected transparently. [1] https://lists.linaro.org/pipermail/eas-dev/2020-July/001488.html Fixes: 1d42509e475c ("sched/fair: Make EAS wakeup placement consider uclamp restrictions") Reported-by: Yun Hsiang <hsiang023167@gmail.com> Signed-off-by: Qais Yousef <qais.yousef@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20220804143609.515789-4-qais.yousef@arm.com Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 244226035a1f9b2b6c326e55ae5188fab4f428cb ]

As reported by Yun Hsiang [1], if a task has its uclamp_min >= 0.8 * 1024,
it'll always pick the previous CPU because fits_capacity() will always
return false in this case.

The new util_fits_cpu() logic should handle this correctly for us beside
more corner cases where similar failures could occur, like when using
UCLAMP_MAX.

We open code uclamp_rq_util_with() except for the clamp() part,
util_fits_cpu() needs the 'raw' values to be passed to it.

Also introduce uclamp_rq_{set, get}() shorthand accessors to get uclamp
value for the rq. Makes the code more readable and ensures the right
rules (use READ_ONCE/WRITE_ONCE) are respected transparently.

[1] https://lists.linaro.org/pipermail/eas-dev/2020-July/001488.html

Fixes: 1d42509e475c ("sched/fair: Make EAS wakeup placement consider uclamp restrictions")
Reported-by: Yun Hsiang <hsiang023167@gmail.com>
Signed-off-by: Qais Yousef <qais.yousef@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220804143609.515789-4-qais.yousef@arm.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
sched: Fix race in task_call_func() 2022-11-14T08:58:32+00:00 Peter Zijlstra peterz@infradead.org 2022-10-26T11:43:00+00:00 91dabf33ae5df271da63e87ad7833e5fdb4a44b9 There is a very narrow race between schedule() and task_call_func(). CPU0 CPU1 __schedule() rq_lock(); prev_state = READ_ONCE(prev->__state); if (... && prev_state) { deactivate_tasl(rq, prev, ...) prev->on_rq = 0; task_call_func() raw_spin_lock_irqsave(p->pi_lock); state = READ_ONCE(p->__state); smp_rmb(); if (... || p->on_rq) // false!!! rq = __task_rq_lock() ret = func(); next = pick_next_task(); rq = context_switch(prev, next) prepare_lock_switch() spin_release(&__rq_lockp(rq)->dep_map...) So while the task is on it's way out, it still holds rq->lock for a little while, and right then task_call_func() comes in and figures it doesn't need rq->lock anymore (because the task is already dequeued -- but still running there) and then the __set_task_frozen() thing observes it's holding rq->lock and yells murder. Avoid this by waiting for p->on_cpu to get cleared, which guarantees the task is fully finished on the old CPU. ( While arguably the fixes tag is 'wrong' -- none of the previous task_call_func() users appears to care for this case. ) Fixes: f5d39b020809 ("freezer,sched: Rewrite core freezer logic") Reported-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Link: https://lkml.kernel.org/r/Y1kdRNNfUeAU+FNl@hirez.programming.kicks-ass.net 
There is a very narrow race between schedule() and task_call_func().

  CPU0						CPU1

  __schedule()
    rq_lock();
    prev_state = READ_ONCE(prev->__state);
    if (... && prev_state) {
      deactivate_tasl(rq, prev, ...)
        prev->on_rq = 0;

						task_call_func()
						  raw_spin_lock_irqsave(p->pi_lock);
						  state = READ_ONCE(p->__state);
						  smp_rmb();
						  if (... || p->on_rq) // false!!!
						    rq = __task_rq_lock()

						  ret = func();

    next = pick_next_task();
    rq = context_switch(prev, next)
      prepare_lock_switch()
        spin_release(&__rq_lockp(rq)->dep_map...)

So while the task is on it's way out, it still holds rq->lock for a
little while, and right then task_call_func() comes in and figures it
doesn't need rq->lock anymore (because the task is already dequeued --
but still running there) and then the __set_task_frozen() thing observes
it's holding rq->lock and yells murder.

Avoid this by waiting for p->on_cpu to get cleared, which guarantees
the task is fully finished on the old CPU.

( While arguably the fixes tag is 'wrong' -- none of the previous
  task_call_func() users appears to care for this case. )

Fixes: f5d39b020809 ("freezer,sched: Rewrite core freezer logic")
Reported-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://lkml.kernel.org/r/Y1kdRNNfUeAU+FNl@hirez.programming.kicks-ass.net
sched: Introduce struct balance_callback to avoid CFI mismatches 2022-10-17T14:41:25+00:00 Kees Cook keescook@chromium.org 2022-10-08T00:07:58+00:00 8e5bad7dccec2014f24497b57d8a8ee0b752c290 Introduce distinct struct balance_callback instead of performing function pointer casting which will trip CFI. Avoids warnings as found by Clang's future -Wcast-function-type-strict option: In file included from kernel/sched/core.c:84: kernel/sched/sched.h:1755:15: warning: cast from 'void (*)(struct rq *)' to 'void (*)(struct callback_head *)' converts to incompatible function type [-Wcast-function-type-strict] head->func = (void (*)(struct callback_head *))func; ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ No binary differences result from this change. This patch is a cleanup based on Brad Spengler/PaX Team's modifications to sched code in their last public patch of grsecurity/PaX based on my understanding of the code. Changes or omissions from the original code are mine and don't reflect the original grsecurity/PaX code. Reported-by: Sami Tolvanen <samitolvanen@google.com> Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Nathan Chancellor <nathan@kernel.org> Link: https://github.com/ClangBuiltLinux/linux/issues/1724 Link: https://lkml.kernel.org/r/20221008000758.2957718-1-keescook@chromium.org 
Introduce distinct struct balance_callback instead of performing function
pointer casting which will trip CFI. Avoids warnings as found by Clang's
future -Wcast-function-type-strict option:

In file included from kernel/sched/core.c:84:
kernel/sched/sched.h:1755:15: warning: cast from 'void (*)(struct rq *)' to 'void (*)(struct callback_head *)' converts to incompatible function type [-Wcast-function-type-strict]
        head->func = (void (*)(struct callback_head *))func;
                     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

No binary differences result from this change.

This patch is a cleanup based on Brad Spengler/PaX Team's modifications
to sched code in their last public patch of grsecurity/PaX based on my
understanding of the code. Changes or omissions from the original code
are mine and don't reflect the original grsecurity/PaX code.

Reported-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Link: https://github.com/ClangBuiltLinux/linux/issues/1724
Link: https://lkml.kernel.org/r/20221008000758.2957718-1-keescook@chromium.org
Merge tag 'sched-psi-2022-10-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2022-10-14T20:03:00+00:00 Linus Torvalds torvalds@linux-foundation.org 2022-10-14T20:03:00+00:00 bd9a3dba185ce6701b41f0341470d3f53bbbbaed Pull PSI updates from Ingo Molnar: - Various performance optimizations, resulting in a 4%-9% speedup in the mmtests/config-scheduler-perfpipe micro-benchmark. - New interface to turn PSI on/off on a per cgroup level. * tag 'sched-psi-2022-10-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched/psi: Per-cgroup PSI accounting disable/re-enable interface sched/psi: Cache parent psi_group to speed up group iteration sched/psi: Consolidate cgroup_psi() sched/psi: Add PSI_IRQ to track IRQ/SOFTIRQ pressure sched/psi: Remove NR_ONCPU task accounting sched/psi: Optimize task switch inside shared cgroups again sched/psi: Move private helpers to sched/stats.h sched/psi: Save percpu memory when !psi_cgroups_enabled sched/psi: Don't create cgroup PSI files when psi_disabled sched/psi: Fix periodic aggregation shut off 
Pull PSI updates from Ingo Molnar:

 - Various performance optimizations, resulting in a 4%-9% speedup in
   the mmtests/config-scheduler-perfpipe micro-benchmark.

 - New interface to turn PSI on/off on a per cgroup level.

* tag 'sched-psi-2022-10-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/psi: Per-cgroup PSI accounting disable/re-enable interface
  sched/psi: Cache parent psi_group to speed up group iteration
  sched/psi: Consolidate cgroup_psi()
  sched/psi: Add PSI_IRQ to track IRQ/SOFTIRQ pressure
  sched/psi: Remove NR_ONCPU task accounting
  sched/psi: Optimize task switch inside shared cgroups again
  sched/psi: Move private helpers to sched/stats.h
  sched/psi: Save percpu memory when !psi_cgroups_enabled
  sched/psi: Don't create cgroup PSI files when psi_disabled
  sched/psi: Fix periodic aggregation shut off
Merge tag 'mm-stable-2022-10-08' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm 2022-10-11T00:53:04+00:00 Linus Torvalds torvalds@linux-foundation.org 2022-10-11T00:53:04+00:00 27bc50fc90647bbf7b734c3fc306a5e61350da53 Pull MM updates from Andrew Morton: - Yu Zhao's Multi-Gen LRU patches are here. They've been under test in linux-next for a couple of months without, to my knowledge, any negative reports (or any positive ones, come to that). - Also the Maple Tree from Liam Howlett. An overlapping range-based tree for vmas. It it apparently slightly more efficient in its own right, but is mainly targeted at enabling work to reduce mmap_lock contention. Liam has identified a number of other tree users in the kernel which could be beneficially onverted to mapletrees. Yu Zhao has identified a hard-to-hit but "easy to fix" lockdep splat at [1]. This has yet to be addressed due to Liam's unfortunately timed vacation. He is now back and we'll get this fixed up. - Dmitry Vyukov introduces KMSAN: the Kernel Memory Sanitizer. It uses clang-generated instrumentation to detect used-unintialized bugs down to the single bit level. KMSAN keeps finding bugs. New ones, as well as the legacy ones. - Yang Shi adds a userspace mechanism (madvise) to induce a collapse of memory into THPs. - Zach O'Keefe has expanded Yang Shi's madvise(MADV_COLLAPSE) to support file/shmem-backed pages. - userfaultfd updates from Axel Rasmussen - zsmalloc cleanups from Alexey Romanov - cleanups from Miaohe Lin: vmscan, hugetlb_cgroup, hugetlb and memory-failure - Huang Ying adds enhancements to NUMA balancing memory tiering mode's page promotion, with a new way of detecting hot pages. - memcg updates from Shakeel Butt: charging optimizations and reduced memory consumption. - memcg cleanups from Kairui Song. - memcg fixes and cleanups from Johannes Weiner. - Vishal Moola provides more folio conversions - Zhang Yi removed ll_rw_block() :( - migration enhancements from Peter Xu - migration error-path bugfixes from Huang Ying - Aneesh Kumar added ability for a device driver to alter the memory tiering promotion paths. For optimizations by PMEM drivers, DRM drivers, etc. - vma merging improvements from Jakub Matěn. - NUMA hinting cleanups from David Hildenbrand. - xu xin added aditional userspace visibility into KSM merging activity. - THP & KSM code consolidation from Qi Zheng. - more folio work from Matthew Wilcox. - KASAN updates from Andrey Konovalov. - DAMON cleanups from Kaixu Xia. - DAMON work from SeongJae Park: fixes, cleanups. - hugetlb sysfs cleanups from Muchun Song. - Mike Kravetz fixes locking issues in hugetlbfs and in hugetlb core. Link: https://lkml.kernel.org/r/CAOUHufZabH85CeUN-MEMgL8gJGzJEWUrkiM58JkTbBhh-jew0Q@mail.gmail.com [1] * tag 'mm-stable-2022-10-08' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (555 commits) hugetlb: allocate vma lock for all sharable vmas hugetlb: take hugetlb vma_lock when clearing vma_lock->vma pointer hugetlb: fix vma lock handling during split vma and range unmapping mglru: mm/vmscan.c: fix imprecise comments mm/mglru: don't sync disk for each aging cycle mm: memcontrol: drop dead CONFIG_MEMCG_SWAP config symbol mm: memcontrol: use do_memsw_account() in a few more places mm: memcontrol: deprecate swapaccounting=0 mode mm: memcontrol: don't allocate cgroup swap arrays when memcg is disabled mm/secretmem: remove reduntant return value mm/hugetlb: add available_huge_pages() func mm: remove unused inline functions from include/linux/mm_inline.h selftests/vm: add selftest for MADV_COLLAPSE of uffd-minor memory selftests/vm: add file/shmem MADV_COLLAPSE selftest for cleared pmd selftests/vm: add thp collapse shmem testing selftests/vm: add thp collapse file and tmpfs testing selftests/vm: modularize thp collapse memory operations selftests/vm: dedup THP helpers mm/khugepaged: add tracepoint to hpage_collapse_scan_file() mm/madvise: add file and shmem support to MADV_COLLAPSE ... 
Pull MM updates from Andrew Morton:

 - Yu Zhao's Multi-Gen LRU patches are here. They've been under test in
   linux-next for a couple of months without, to my knowledge, any
   negative reports (or any positive ones, come to that).

 - Also the Maple Tree from Liam Howlett. An overlapping range-based
   tree for vmas. It it apparently slightly more efficient in its own
   right, but is mainly targeted at enabling work to reduce mmap_lock
   contention.

   Liam has identified a number of other tree users in the kernel which
   could be beneficially onverted to mapletrees.

   Yu Zhao has identified a hard-to-hit but "easy to fix" lockdep splat
   at [1]. This has yet to be addressed due to Liam's unfortunately
   timed vacation. He is now back and we'll get this fixed up.

 - Dmitry Vyukov introduces KMSAN: the Kernel Memory Sanitizer. It uses
   clang-generated instrumentation to detect used-unintialized bugs down
   to the single bit level.

   KMSAN keeps finding bugs. New ones, as well as the legacy ones.

 - Yang Shi adds a userspace mechanism (madvise) to induce a collapse of
   memory into THPs.

 - Zach O'Keefe has expanded Yang Shi's madvise(MADV_COLLAPSE) to
   support file/shmem-backed pages.

 - userfaultfd updates from Axel Rasmussen

 - zsmalloc cleanups from Alexey Romanov

 - cleanups from Miaohe Lin: vmscan, hugetlb_cgroup, hugetlb and
   memory-failure

 - Huang Ying adds enhancements to NUMA balancing memory tiering mode's
   page promotion, with a new way of detecting hot pages.

 - memcg updates from Shakeel Butt: charging optimizations and reduced
   memory consumption.

 - memcg cleanups from Kairui Song.

 - memcg fixes and cleanups from Johannes Weiner.

 - Vishal Moola provides more folio conversions

 - Zhang Yi removed ll_rw_block() :(

 - migration enhancements from Peter Xu

 - migration error-path bugfixes from Huang Ying

 - Aneesh Kumar added ability for a device driver to alter the memory
   tiering promotion paths. For optimizations by PMEM drivers, DRM
   drivers, etc.

 - vma merging improvements from Jakub Matěn.

 - NUMA hinting cleanups from David Hildenbrand.

 - xu xin added aditional userspace visibility into KSM merging
   activity.

 - THP & KSM code consolidation from Qi Zheng.

 - more folio work from Matthew Wilcox.

 - KASAN updates from Andrey Konovalov.

 - DAMON cleanups from Kaixu Xia.

 - DAMON work from SeongJae Park: fixes, cleanups.

 - hugetlb sysfs cleanups from Muchun Song.

 - Mike Kravetz fixes locking issues in hugetlbfs and in hugetlb core.

Link: https://lkml.kernel.org/r/CAOUHufZabH85CeUN-MEMgL8gJGzJEWUrkiM58JkTbBhh-jew0Q@mail.gmail.com [1]

* tag 'mm-stable-2022-10-08' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (555 commits)
  hugetlb: allocate vma lock for all sharable vmas
  hugetlb: take hugetlb vma_lock when clearing vma_lock->vma pointer
  hugetlb: fix vma lock handling during split vma and range unmapping
  mglru: mm/vmscan.c: fix imprecise comments
  mm/mglru: don't sync disk for each aging cycle
  mm: memcontrol: drop dead CONFIG_MEMCG_SWAP config symbol
  mm: memcontrol: use do_memsw_account() in a few more places
  mm: memcontrol: deprecate swapaccounting=0 mode
  mm: memcontrol: don't allocate cgroup swap arrays when memcg is disabled
  mm/secretmem: remove reduntant return value
  mm/hugetlb: add available_huge_pages() func
  mm: remove unused inline functions from include/linux/mm_inline.h
  selftests/vm: add selftest for MADV_COLLAPSE of uffd-minor memory
  selftests/vm: add file/shmem MADV_COLLAPSE selftest for cleared pmd
  selftests/vm: add thp collapse shmem testing
  selftests/vm: add thp collapse file and tmpfs testing
  selftests/vm: modularize thp collapse memory operations
  selftests/vm: dedup THP helpers
  mm/khugepaged: add tracepoint to hpage_collapse_scan_file()
  mm/madvise: add file and shmem support to MADV_COLLAPSE
  ...
Merge tag 'bitmap-6.1-rc1' of https://github.com/norov/linux 2022-10-10T19:49:34+00:00 Linus Torvalds torvalds@linux-foundation.org 2022-10-10T19:49:34+00:00 d4013bc4d49f6da8178a340348369bb9920225c9 Pull bitmap updates from Yury Norov: - Fix unsigned comparison to -1 in CPUMAP_FILE_MAX_BYTES (Phil Auld) - cleanup nr_cpu_ids vs nr_cpumask_bits mess (me) This series cleans that mess and adds new config FORCE_NR_CPUS that allows to optimize cpumask subsystem if the number of CPUs is known at compile-time. - optimize find_bit() functions (me) Reworks find_bit() functions based on new FIND_{FIRST,NEXT}_BIT() macros. - add find_nth_bit() (me) Adds find_nth_bit(), which is ~70 times faster than bitcounting with for_each() loop: for_each_set_bit(bit, mask, size) if (n-- == 0) return bit; Also adds bitmap_weight_and() to let people replace this pattern: tmp = bitmap_alloc(nbits); bitmap_and(tmp, map1, map2, nbits); weight = bitmap_weight(tmp, nbits); bitmap_free(tmp); with a single bitmap_weight_and() call. - repair cpumask_check() (me) After switching cpumask to use nr_cpu_ids, cpumask_check() started generating many false-positive warnings. This series fixes it. - Add for_each_cpu_andnot() and for_each_cpu_andnot() (Valentin Schneider) Extends the API with one more function and applies it in sched/core. * tag 'bitmap-6.1-rc1' of https://github.com/norov/linux: (28 commits) sched/core: Merge cpumask_andnot()+for_each_cpu() into for_each_cpu_andnot() lib/test_cpumask: Add for_each_cpu_and(not) tests cpumask: Introduce for_each_cpu_andnot() lib/find_bit: Introduce find_next_andnot_bit() cpumask: fix checking valid cpu range lib/bitmap: add tests for for_each() loops lib/find: optimize for_each() macros lib/bitmap: introduce for_each_set_bit_wrap() macro lib/find_bit: add find_next{,_and}_bit_wrap cpumask: switch for_each_cpu{,_not} to use for_each_bit() net: fix cpu_max_bits_warn() usage in netif_attrmask_next{,_and} cpumask: add cpumask_nth_{,and,andnot} lib/bitmap: remove bitmap_ord_to_pos lib/bitmap: add tests for find_nth_bit() lib: add find_nth{,_and,_andnot}_bit() lib/bitmap: add bitmap_weight_and() lib/bitmap: don't call __bitmap_weight() in kernel code tools: sync find_bit() implementation lib/find_bit: optimize find_next_bit() functions lib/find_bit: create find_first_zero_bit_le() ... 
Pull bitmap updates from Yury Norov:

 - Fix unsigned comparison to -1 in CPUMAP_FILE_MAX_BYTES (Phil Auld)

 - cleanup nr_cpu_ids vs nr_cpumask_bits mess (me)

   This series cleans that mess and adds new config FORCE_NR_CPUS that
   allows to optimize cpumask subsystem if the number of CPUs is known
   at compile-time.

 - optimize find_bit() functions (me)

   Reworks find_bit() functions based on new FIND_{FIRST,NEXT}_BIT()
   macros.

 - add find_nth_bit() (me)

   Adds find_nth_bit(), which is ~70 times faster than bitcounting with
   for_each() loop:

	for_each_set_bit(bit, mask, size)
		if (n-- == 0)
			return bit;

   Also adds bitmap_weight_and() to let people replace this pattern:

	tmp = bitmap_alloc(nbits);
	bitmap_and(tmp, map1, map2, nbits);
	weight = bitmap_weight(tmp, nbits);
	bitmap_free(tmp);

   with a single bitmap_weight_and() call.

 - repair cpumask_check() (me)

   After switching cpumask to use nr_cpu_ids, cpumask_check() started
   generating many false-positive warnings. This series fixes it.

 - Add for_each_cpu_andnot() and for_each_cpu_andnot() (Valentin
   Schneider)

   Extends the API with one more function and applies it in sched/core.

* tag 'bitmap-6.1-rc1' of https://github.com/norov/linux: (28 commits)
  sched/core: Merge cpumask_andnot()+for_each_cpu() into for_each_cpu_andnot()
  lib/test_cpumask: Add for_each_cpu_and(not) tests
  cpumask: Introduce for_each_cpu_andnot()
  lib/find_bit: Introduce find_next_andnot_bit()
  cpumask: fix checking valid cpu range
  lib/bitmap: add tests for for_each() loops
  lib/find: optimize for_each() macros
  lib/bitmap: introduce for_each_set_bit_wrap() macro
  lib/find_bit: add find_next{,_and}_bit_wrap
  cpumask: switch for_each_cpu{,_not} to use for_each_bit()
  net: fix cpu_max_bits_warn() usage in netif_attrmask_next{,_and}
  cpumask: add cpumask_nth_{,and,andnot}
  lib/bitmap: remove bitmap_ord_to_pos
  lib/bitmap: add tests for find_nth_bit()
  lib: add find_nth{,_and,_andnot}_bit()
  lib/bitmap: add bitmap_weight_and()
  lib/bitmap: don't call __bitmap_weight() in kernel code
  tools: sync find_bit() implementation
  lib/find_bit: optimize find_next_bit() functions
  lib/find_bit: create find_first_zero_bit_le()
  ...
Merge tag 'sched-core-2022-10-07' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2022-10-10T16:10:28+00:00 Linus Torvalds torvalds@linux-foundation.org 2022-10-10T16:10:28+00:00 30c999937f69abf935b0228b8411713737377d9e Pull scheduler updates from Ingo Molnar: "Debuggability: - Change most occurances of BUG_ON() to WARN_ON_ONCE() - Reorganize & fix TASK_ state comparisons, turn it into a bitmap - Update/fix misc scheduler debugging facilities Load-balancing & regular scheduling: - Improve the behavior of the scheduler in presence of lot of SCHED_IDLE tasks - in particular they should not impact other scheduling classes. - Optimize task load tracking, cleanups & fixes - Clean up & simplify misc load-balancing code Freezer: - Rewrite the core freezer to behave better wrt thawing and be simpler in general, by replacing PF_FROZEN with TASK_FROZEN & fixing/adjusting all the fallout. Deadline scheduler: - Fix the DL capacity-aware code - Factor out dl_task_is_earliest_deadline() & replenish_dl_new_period() - Relax/optimize locking in task_non_contending() Cleanups: - Factor out the update_current_exec_runtime() helper - Various cleanups, simplifications" * tag 'sched-core-2022-10-07' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (41 commits) sched: Fix more TASK_state comparisons sched: Fix TASK_state comparisons sched/fair: Move call to list_last_entry() in detach_tasks sched/fair: Cleanup loop_max and loop_break sched/fair: Make sure to try to detach at least one movable task sched: Show PF_flag holes freezer,sched: Rewrite core freezer logic sched: Widen TAKS_state literals sched/wait: Add wait_event_state() sched/completion: Add wait_for_completion_state() sched: Add TASK_ANY for wait_task_inactive() sched: Change wait_task_inactive()s match_state freezer,umh: Clean up freezer/initrd interaction freezer: Have {,un}lock_system_sleep() save/restore flags sched: Rename task_running() to task_on_cpu() sched/fair: Cleanup for SIS_PROP sched/fair: Default to false in test_idle_cores() sched/fair: Remove useless check in select_idle_core() sched/fair: Avoid double search on same cpu sched/fair: Remove redundant check in select_idle_smt() ... 
Pull scheduler updates from Ingo Molnar:
 "Debuggability:

   - Change most occurances of BUG_ON() to WARN_ON_ONCE()

   - Reorganize & fix TASK_ state comparisons, turn it into a bitmap

   - Update/fix misc scheduler debugging facilities

  Load-balancing & regular scheduling:

   - Improve the behavior of the scheduler in presence of lot of
     SCHED_IDLE tasks - in particular they should not impact other
     scheduling classes.

   - Optimize task load tracking, cleanups & fixes

   - Clean up & simplify misc load-balancing code

  Freezer:

   - Rewrite the core freezer to behave better wrt thawing and be
     simpler in general, by replacing PF_FROZEN with TASK_FROZEN &
     fixing/adjusting all the fallout.

  Deadline scheduler:

   - Fix the DL capacity-aware code

   - Factor out dl_task_is_earliest_deadline() &
     replenish_dl_new_period()

   - Relax/optimize locking in task_non_contending()

  Cleanups:

   - Factor out the update_current_exec_runtime() helper

   - Various cleanups, simplifications"

* tag 'sched-core-2022-10-07' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (41 commits)
  sched: Fix more TASK_state comparisons
  sched: Fix TASK_state comparisons
  sched/fair: Move call to list_last_entry() in detach_tasks
  sched/fair: Cleanup loop_max and loop_break
  sched/fair: Make sure to try to detach at least one movable task
  sched: Show PF_flag holes
  freezer,sched: Rewrite core freezer logic
  sched: Widen TAKS_state literals
  sched/wait: Add wait_event_state()
  sched/completion: Add wait_for_completion_state()
  sched: Add TASK_ANY for wait_task_inactive()
  sched: Change wait_task_inactive()s match_state
  freezer,umh: Clean up freezer/initrd interaction
  freezer: Have {,un}lock_system_sleep() save/restore flags
  sched: Rename task_running() to task_on_cpu()
  sched/fair: Cleanup for SIS_PROP
  sched/fair: Default to false in test_idle_cores()
  sched/fair: Remove useless check in select_idle_core()
  sched/fair: Avoid double search on same cpu
  sched/fair: Remove redundant check in select_idle_smt()
  ...
sched/core: Merge cpumask_andnot()+for_each_cpu() into for_each_cpu_andnot() 2022-10-06T12:57:36+00:00 Valentin Schneider vschneid@redhat.com 2022-10-03T15:34:20+00:00 585463f0d58aa4d29b744c7c53b222b8028de87f This removes the second use of the sched_core_mask temporary mask. Suggested-by: Yury Norov <yury.norov@gmail.com> Signed-off-by: Valentin Schneider <vschneid@redhat.com> 
This removes the second use of the sched_core_mask temporary mask.

Suggested-by: Yury Norov <yury.norov@gmail.com>
Signed-off-by: Valentin Schneider <vschneid@redhat.com>
sched: Fix TASK_state comparisons 2022-09-28T08:00:16+00:00 Peter Zijlstra peterz@infradead.org 2022-09-27T19:02:34+00:00 5aec788aeb8eb74282b75ac1b317beb0fbb69a42 Task state is fundamentally a bitmask; direct comparisons are probably not working as intended. Specifically the normal wait-state have a number of possible modifiers: TASK_UNINTERRUPTIBLE: TASK_WAKEKILL, TASK_NOLOAD, TASK_FREEZABLE TASK_INTERRUPTIBLE: TASK_FREEZABLE Specifically, the addition of TASK_FREEZABLE wrecked __wait_is_interruptible(). This however led to an audit of direct comparisons yielding the rest of the changes. Fixes: f5d39b020809 ("freezer,sched: Rewrite core freezer logic") Reported-by: Christian Borntraeger <borntraeger@linux.ibm.com> Debugged-by: Christian Borntraeger <borntraeger@linux.ibm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Christian Borntraeger <borntraeger@linux.ibm.com> 
Task state is fundamentally a bitmask; direct comparisons are probably
not working as intended. Specifically the normal wait-state have
a number of possible modifiers:

  TASK_UNINTERRUPTIBLE:	TASK_WAKEKILL, TASK_NOLOAD, TASK_FREEZABLE
  TASK_INTERRUPTIBLE:   TASK_FREEZABLE

Specifically, the addition of TASK_FREEZABLE wrecked
__wait_is_interruptible(). This however led to an audit of direct
comparisons yielding the rest of the changes.

Fixes: f5d39b020809 ("freezer,sched: Rewrite core freezer logic")
Reported-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Debugged-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Christian Borntraeger <borntraeger@linux.ibm.com>
mm: multi-gen LRU: support page table walks 2022-09-27T02:46:09+00:00 Yu Zhao yuzhao@google.com 2022-09-18T08:00:05+00:00 bd74fdaea146029e4fa12c6de89adbe0779348a9 To further exploit spatial locality, the aging prefers to walk page tables to search for young PTEs and promote hot pages. A kill switch will be added in the next patch to disable this behavior. When disabled, the aging relies on the rmap only. NB: this behavior has nothing similar with the page table scanning in the 2.4 kernel [1], which searches page tables for old PTEs, adds cold pages to swapcache and unmaps them. To avoid confusion, the term "iteration" specifically means the traversal of an entire mm_struct list; the term "walk" will be applied to page tables and the rmap, as usual. An mm_struct list is maintained for each memcg, and an mm_struct follows its owner task to the new memcg when this task is migrated. Given an lruvec, the aging iterates lruvec_memcg()->mm_list and calls walk_page_range() with each mm_struct on this list to promote hot pages before it increments max_seq. When multiple page table walkers iterate the same list, each of them gets a unique mm_struct; therefore they can run concurrently. Page table walkers ignore any misplaced pages, e.g., if an mm_struct was migrated, pages it left in the previous memcg will not be promoted when its current memcg is under reclaim. Similarly, page table walkers will not promote pages from nodes other than the one under reclaim. This patch uses the following optimizations when walking page tables: 1. It tracks the usage of mm_struct's between context switches so that page table walkers can skip processes that have been sleeping since the last iteration. 2. It uses generational Bloom filters to record populated branches so that page table walkers can reduce their search space based on the query results, e.g., to skip page tables containing mostly holes or misplaced pages. 3. It takes advantage of the accessed bit in non-leaf PMD entries when CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG=y. 4. It does not zigzag between a PGD table and the same PMD table spanning multiple VMAs. IOW, it finishes all the VMAs within the range of the same PMD table before it returns to a PGD table. This improves the cache performance for workloads that have large numbers of tiny VMAs [2], especially when CONFIG_PGTABLE_LEVELS=5. Server benchmark results: Single workload: fio (buffered I/O): no change Single workload: memcached (anon): +[8, 10]% Ops/sec KB/sec patch1-7: 1147696.57 44640.29 patch1-8: 1245274.91 48435.66 Configurations: no change Client benchmark results: kswapd profiles: patch1-7 48.16% lzo1x_1_do_compress (real work) 8.20% page_vma_mapped_walk (overhead) 7.06% _raw_spin_unlock_irq 2.92% ptep_clear_flush 2.53% __zram_bvec_write 2.11% do_raw_spin_lock 2.02% memmove 1.93% lru_gen_look_around 1.56% free_unref_page_list 1.40% memset patch1-8 49.44% lzo1x_1_do_compress (real work) 6.19% page_vma_mapped_walk (overhead) 5.97% _raw_spin_unlock_irq 3.13% get_pfn_folio 2.85% ptep_clear_flush 2.42% __zram_bvec_write 2.08% do_raw_spin_lock 1.92% memmove 1.44% alloc_zspage 1.36% memset Configurations: no change Thanks to the following developers for their efforts [3]. kernel test robot <lkp@intel.com> [1] https://lwn.net/Articles/23732/ [2] https://llvm.org/docs/ScudoHardenedAllocator.html [3] https://lore.kernel.org/r/202204160827.ekEARWQo-lkp@intel.com/ Link: https://lkml.kernel.org/r/20220918080010.2920238-9-yuzhao@google.com Signed-off-by: Yu Zhao <yuzhao@google.com> Acked-by: Brian Geffon <bgeffon@google.com> Acked-by: Jan Alexander Steffens (heftig) <heftig@archlinux.org> Acked-by: Oleksandr Natalenko <oleksandr@natalenko.name> Acked-by: Steven Barrett <steven@liquorix.net> Acked-by: Suleiman Souhlal <suleiman@google.com> Tested-by: Daniel Byrne <djbyrne@mtu.edu> Tested-by: Donald Carr <d@chaos-reins.com> Tested-by: Holger Hoffstätte <holger@applied-asynchrony.com> Tested-by: Konstantin Kharlamov <Hi-Angel@yandex.ru> Tested-by: Shuang Zhai <szhai2@cs.rochester.edu> Tested-by: Sofia Trinh <sofia.trinh@edi.works> Tested-by: Vaibhav Jain <vaibhav@linux.ibm.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Barry Song <baohua@kernel.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Hillf Danton <hdanton@sina.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Michael Larabel <Michael@MichaelLarabel.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Qi Zheng <zhengqi.arch@bytedance.com> Cc: Tejun Heo <tj@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> 
To further exploit spatial locality, the aging prefers to walk page tables
to search for young PTEs and promote hot pages.  A kill switch will be
added in the next patch to disable this behavior.  When disabled, the
aging relies on the rmap only.

NB: this behavior has nothing similar with the page table scanning in the
2.4 kernel [1], which searches page tables for old PTEs, adds cold pages
to swapcache and unmaps them.

To avoid confusion, the term "iteration" specifically means the traversal
of an entire mm_struct list; the term "walk" will be applied to page
tables and the rmap, as usual.

An mm_struct list is maintained for each memcg, and an mm_struct follows
its owner task to the new memcg when this task is migrated.  Given an
lruvec, the aging iterates lruvec_memcg()->mm_list and calls
walk_page_range() with each mm_struct on this list to promote hot pages
before it increments max_seq.

When multiple page table walkers iterate the same list, each of them gets
a unique mm_struct; therefore they can run concurrently.  Page table
walkers ignore any misplaced pages, e.g., if an mm_struct was migrated,
pages it left in the previous memcg will not be promoted when its current
memcg is under reclaim.  Similarly, page table walkers will not promote
pages from nodes other than the one under reclaim.

This patch uses the following optimizations when walking page tables:
1. It tracks the usage of mm_struct's between context switches so that
   page table walkers can skip processes that have been sleeping since
   the last iteration.
2. It uses generational Bloom filters to record populated branches so
   that page table walkers can reduce their search space based on the
   query results, e.g., to skip page tables containing mostly holes or
   misplaced pages.
3. It takes advantage of the accessed bit in non-leaf PMD entries when
   CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG=y.
4. It does not zigzag between a PGD table and the same PMD table
   spanning multiple VMAs. IOW, it finishes all the VMAs within the
   range of the same PMD table before it returns to a PGD table. This
   improves the cache performance for workloads that have large
   numbers of tiny VMAs [2], especially when CONFIG_PGTABLE_LEVELS=5.

Server benchmark results:
  Single workload:
    fio (buffered I/O): no change

  Single workload:
    memcached (anon): +[8, 10]%
                Ops/sec      KB/sec
      patch1-7: 1147696.57   44640.29
      patch1-8: 1245274.91   48435.66

  Configurations:
    no change

Client benchmark results:
  kswapd profiles:
    patch1-7
      48.16%  lzo1x_1_do_compress (real work)
       8.20%  page_vma_mapped_walk (overhead)
       7.06%  _raw_spin_unlock_irq
       2.92%  ptep_clear_flush
       2.53%  __zram_bvec_write
       2.11%  do_raw_spin_lock
       2.02%  memmove
       1.93%  lru_gen_look_around
       1.56%  free_unref_page_list
       1.40%  memset

    patch1-8
      49.44%  lzo1x_1_do_compress (real work)
       6.19%  page_vma_mapped_walk (overhead)
       5.97%  _raw_spin_unlock_irq
       3.13%  get_pfn_folio
       2.85%  ptep_clear_flush
       2.42%  __zram_bvec_write
       2.08%  do_raw_spin_lock
       1.92%  memmove
       1.44%  alloc_zspage
       1.36%  memset

  Configurations:
    no change

Thanks to the following developers for their efforts [3].
  kernel test robot <lkp@intel.com>

[1] https://lwn.net/Articles/23732/
[2] https://llvm.org/docs/ScudoHardenedAllocator.html
[3] https://lore.kernel.org/r/202204160827.ekEARWQo-lkp@intel.com/

Link: https://lkml.kernel.org/r/20220918080010.2920238-9-yuzhao@google.com
Signed-off-by: Yu Zhao <yuzhao@google.com>
Acked-by: Brian Geffon <bgeffon@google.com>
Acked-by: Jan Alexander Steffens (heftig) <heftig@archlinux.org>
Acked-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Acked-by: Steven Barrett <steven@liquorix.net>
Acked-by: Suleiman Souhlal <suleiman@google.com>
Tested-by: Daniel Byrne <djbyrne@mtu.edu>
Tested-by: Donald Carr <d@chaos-reins.com>
Tested-by: Holger Hoffstätte <holger@applied-asynchrony.com>
Tested-by: Konstantin Kharlamov <Hi-Angel@yandex.ru>
Tested-by: Shuang Zhai <szhai2@cs.rochester.edu>
Tested-by: Sofia Trinh <sofia.trinh@edi.works>
Tested-by: Vaibhav Jain <vaibhav@linux.ibm.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michael Larabel <Michael@MichaelLarabel.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>