The patch titled Subject: mm, slub: remove conditional locking parameter from flush_slab() has been added to the -mm tree. Its filename is mm-slub-remove-conditional-locking-parameter-from-flush_slab.patch This patch should soon appear at https://ozlabs.org/~akpm/mmots/broken-out/mm-slub-remove-conditional-locking-parameter-from-flush_slab.patch and later at https://ozlabs.org/~akpm/mmotm/broken-out/mm-slub-remove-conditional-locking-parameter-from-flush_slab.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Vlastimil Babka <vbabka@xxxxxxx> Subject: mm, slub: remove conditional locking parameter from flush_slab() flush_slab() is called either as part of work scheduled on given live cpu, or called as a cleanup for another cpu that went offline. In the first case it needs to hold the cpu_slab->lock local lock when updating the protected kmem_cache_cpu fields. This is now achieved by a "bool lock" parameter. To avoid the conditional locking, we can instead lock unconditionally in flush_slab() for live cpus, and opencode the variant without locking in __flush_cpu_slab() for the dead cpus. Link: https://lkml.kernel.org/r/1ae902f7-c500-f9e8-1b4f-077beade0f42@xxxxxxx Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx> Reported-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Suggested-by: Mike Galbraith <efault@xxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/slub.c | 23 ++++++++++++++--------- 1 file changed, 14 insertions(+), 9 deletions(-) --- a/mm/slub.c~mm-slub-remove-conditional-locking-parameter-from-flush_slab +++ a/mm/slub.c @@ -2566,15 +2566,13 @@ static inline void unfreeze_partials_cpu #endif /* CONFIG_SLUB_CPU_PARTIAL */ -static inline void flush_slab(struct kmem_cache *s, struct kmem_cache_cpu *c, - bool lock) +static inline void flush_slab(struct kmem_cache *s, struct kmem_cache_cpu *c) { unsigned long flags; void *freelist; struct page *page; - if (lock) - local_lock_irqsave(&s->cpu_slab->lock, flags); + local_lock_irqsave(&s->cpu_slab->lock, flags); freelist = c->freelist; page = c->page; @@ -2583,8 +2581,7 @@ static inline void flush_slab(struct kme c->freelist = NULL; c->tid = next_tid(c->tid); - if (lock) - local_unlock_irqrestore(&s->cpu_slab->lock, flags); + local_unlock_irqrestore(&s->cpu_slab->lock, flags); if (page) deactivate_slab(s, page, freelist); @@ -2595,9 +2592,17 @@ static inline void flush_slab(struct kme static inline void __flush_cpu_slab(struct kmem_cache *s, int cpu) { struct kmem_cache_cpu *c = per_cpu_ptr(s->cpu_slab, cpu); + struct page *page = c->page; + void *freelist = c->freelist; - if (c->page) - flush_slab(s, c, false); + c->page = NULL; + c->freelist = NULL; + c->tid = next_tid(c->tid); + + if (page) { + deactivate_slab(s, page, freelist); + stat(s, CPUSLAB_FLUSH); + } unfreeze_partials_cpu(s, c); } @@ -2625,7 +2630,7 @@ static void flush_cpu_slab(struct work_s c = this_cpu_ptr(s->cpu_slab); if (c->page) - flush_slab(s, c, true); + flush_slab(s, c); unfreeze_partials(s); } _ Patches currently in -mm which might be from vbabka@xxxxxxx are mm-slub-dont-call-flush_all-from-slab_debug_trace_open.patch mm-slub-allocate-private-object-map-for-debugfs-listings.patch mm-slub-allocate-private-object-map-for-validate_slab_cache.patch mm-slub-dont-disable-irq-for-debug_check_no_locks_freed.patch mm-slub-remove-redundant-unfreeze_partials-from-put_cpu_partial.patch mm-slub-unify-cmpxchg_double_slab-and-__cmpxchg_double_slab.patch mm-slub-extract-get_partial-from-new_slab_objects.patch mm-slub-dissolve-new_slab_objects-into-___slab_alloc.patch mm-slub-return-slab-page-from-get_partial-and-set-c-page-afterwards.patch mm-slub-restructure-new-page-checks-in-___slab_alloc.patch mm-slub-simplify-kmem_cache_cpu-and-tid-setup.patch mm-slub-move-disabling-enabling-irqs-to-___slab_alloc.patch mm-slub-do-initial-checks-in-___slab_alloc-with-irqs-enabled.patch mm-slub-move-disabling-irqs-closer-to-get_partial-in-___slab_alloc.patch mm-slub-restore-irqs-around-calling-new_slab.patch mm-slub-validate-slab-from-partial-list-or-page-allocator-before-making-it-cpu-slab.patch mm-slub-check-new-pages-with-restored-irqs.patch mm-slub-stop-disabling-irqs-around-get_partial.patch mm-slub-move-reset-of-c-page-and-freelist-out-of-deactivate_slab.patch mm-slub-make-locking-in-deactivate_slab-irq-safe.patch mm-slub-call-deactivate_slab-without-disabling-irqs.patch mm-slub-move-irq-control-into-unfreeze_partials.patch mm-slub-discard-slabs-in-unfreeze_partials-without-irqs-disabled.patch mm-slub-detach-whole-partial-list-at-once-in-unfreeze_partials.patch mm-slub-separate-detaching-of-partial-list-in-unfreeze_partials-from-unfreezing.patch mm-slub-only-disable-irq-with-spin_lock-in-__unfreeze_partials.patch mm-slub-dont-disable-irqs-in-slub_cpu_dead.patch mm-slab-make-flush_slab-possible-to-call-with-irqs-enabled.patch mm-slub-optionally-save-restore-irqs-in-slab_lock.patch mm-slub-make-slab_lock-disable-irqs-with-preempt_rt.patch mm-slub-protect-put_cpu_partial-with-disabled-irqs-instead-of-cmpxchg.patch mm-slub-use-migrate_disable-on-preempt_rt.patch mm-slub-convert-kmem_cpu_slab-protection-to-local_lock.patch mm-slub-remove-conditional-locking-parameter-from-flush_slab.patch