The patch titled
Subject: mm, slub: call deactivate_slab() without disabling irqs
has been added to the -mm tree. Its filename is
mm-slub-call-deactivate_slab-without-disabling-irqs.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-slub-call-deactivate_slab-without-disabling-irqs.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-slub-call-deactivate_slab-without-disabling-irqs.patch
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------------------------------------------------------
From: Vlastimil Babka <vbabka@xxxxxxx>
Subject: mm, slub: call deactivate_slab() without disabling irqs
The function is now safe to be called with irqs enabled, so move the calls
outside of irq disabled sections.
When called from ___slab_alloc() -> flush_slab() we have irqs disabled, so
to reenable them before deactivate_slab() we need to open-code
flush_slab() in ___slab_alloc() and reenable irqs after modifying the
kmem_cache_cpu fields. But that means a IRQ handler meanwhile might have
assigned a new page to kmem_cache_cpu.page so we have to retry the whole
check.
The remaining callers of flush_slab() are the IPI handler which has
disabled irqs anyway, and slub_cpu_dead() which will be dealt with in the
following patch.
Link: https://lkml.kernel.org/r/20210805152000.12817-22-vbabka@xxxxxxx
Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Jann Horn <jannh@xxxxxxxxxx>
Cc: Jesper Dangaard Brouer <brouer@xxxxxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Cc: Mike Galbraith <efault@xxxxxx>
Cc: Pekka Enberg <penberg@xxxxxxxxxx>
Cc: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/slub.c | 24 +++++++++++++++++++-----
1 file changed, 19 insertions(+), 5 deletions(-)
--- a/mm/slub.c~mm-slub-call-deactivate_slab-without-disabling-irqs
+++ a/mm/slub.c
@@ -2752,8 +2752,8 @@ deactivate_slab:
freelist = c->freelist;
c->page = NULL;
c->freelist = NULL;
- deactivate_slab(s, page, freelist);
local_irq_restore(flags);
+ deactivate_slab(s, page, freelist);
new_slab:
@@ -2821,18 +2821,32 @@ check_new_page:
*/
goto return_single;
+retry_load_page:
+
local_irq_save(flags);
- if (unlikely(c->page))
- flush_slab(s, c);
+ if (unlikely(c->page)) {
+ void *flush_freelist = c->freelist;
+ struct page *flush_page = c->page;
+
+ c->page = NULL;
+ c->freelist = NULL;
+ c->tid = next_tid(c->tid);
+
+ local_irq_restore(flags);
+
+ deactivate_slab(s, flush_page, flush_freelist);
+
+ stat(s, CPUSLAB_FLUSH);
+
+ goto retry_load_page;
+ }
c->page = page;
goto load_freelist;
return_single:
- local_irq_save(flags);
deactivate_slab(s, page, get_freepointer(s, freelist));
- local_irq_restore(flags);
return freelist;
}
_
Patches currently in -mm which might be from vbabka@xxxxxxx are
mm-slub-fix-slub_debug-disablement-for-list-of-slabs.patch
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
