The patch titled
Subject: mm, slub: do initial checks in ___slab_alloc() with irqs enabled
has been added to the -mm tree. Its filename is
mm-slub-do-initial-checks-in-___slab_alloc-with-irqs-enabled.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-slub-do-initial-checks-in-___slab_alloc-with-irqs-enabled.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-slub-do-initial-checks-in-___slab_alloc-with-irqs-enabled.patch
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*** 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: do initial checks in ___slab_alloc() with irqs enabled
As another step of shortening irq disabled sections in ___slab_alloc(),
delay disabling irqs until we pass the initial checks if there is a cached
percpu slab and it's suitable for our allocation.
Now we have to recheck c->page after actually disabling irqs as an
allocation in irq handler might have replaced it.
Link: https://lkml.kernel.org/r/20210805152000.12817-14-vbabka@xxxxxxx
Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
Acked-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
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: 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 | 41 ++++++++++++++++++++++++++++++++---------
1 file changed, 32 insertions(+), 9 deletions(-)
--- a/mm/slub.c~mm-slub-do-initial-checks-in-___slab_alloc-with-irqs-enabled
+++ a/mm/slub.c
@@ -2668,8 +2668,9 @@ static void *___slab_alloc(struct kmem_c
stat(s, ALLOC_SLOWPATH);
- local_irq_save(flags);
- page = c->page;
+reread_page:
+
+ page = READ_ONCE(c->page);
if (!page) {
/*
* if the node is not online or has no normal memory, just
@@ -2678,6 +2679,11 @@ static void *___slab_alloc(struct kmem_c
if (unlikely(node != NUMA_NO_NODE &&
!node_isset(node, slab_nodes)))
node = NUMA_NO_NODE;
+ local_irq_save(flags);
+ if (unlikely(c->page)) {
+ local_irq_restore(flags);
+ goto reread_page;
+ }
goto new_slab;
}
redo:
@@ -2692,8 +2698,7 @@ redo:
goto redo;
} else {
stat(s, ALLOC_NODE_MISMATCH);
- deactivate_slab(s, page, c->freelist, c);
- goto new_slab;
+ goto deactivate_slab;
}
}
@@ -2702,12 +2707,15 @@ redo:
* PFMEMALLOC but right now, we are losing the pfmemalloc
* information when the page leaves the per-cpu allocator
*/
- if (unlikely(!pfmemalloc_match(page, gfpflags))) {
- deactivate_slab(s, page, c->freelist, c);
- goto new_slab;
- }
+ if (unlikely(!pfmemalloc_match(page, gfpflags)))
+ goto deactivate_slab;
- /* must check again c->freelist in case of cpu migration or IRQ */
+ /* must check again c->page in case IRQ handler changed it */
+ local_irq_save(flags);
+ if (unlikely(page != c->page)) {
+ local_irq_restore(flags);
+ goto reread_page;
+ }
freelist = c->freelist;
if (freelist)
goto load_freelist;
@@ -2723,6 +2731,9 @@ redo:
stat(s, ALLOC_REFILL);
load_freelist:
+
+ lockdep_assert_irqs_disabled();
+
/*
* freelist is pointing to the list of objects to be used.
* page is pointing to the page from which the objects are obtained.
@@ -2734,11 +2745,23 @@ load_freelist:
local_irq_restore(flags);
return freelist;
+deactivate_slab:
+
+ local_irq_save(flags);
+ if (page != c->page) {
+ local_irq_restore(flags);
+ goto reread_page;
+ }
+ deactivate_slab(s, page, c->freelist, c);
+
new_slab:
+ lockdep_assert_irqs_disabled();
+
if (slub_percpu_partial(c)) {
page = c->page = slub_percpu_partial(c);
slub_set_percpu_partial(c, page);
+ local_irq_restore(flags);
stat(s, CPU_PARTIAL_ALLOC);
goto redo;
}
_
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
