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mm, slub: make locking in deactivate_slab() irq-safe 

dectivate_slab() now no longer touches the kmem_cache_cpu structure, so it will
be possible to call it with irqs enabled. Just convert the spin_lock calls to
their irq saving/restoring variants to make it irq-safe.

Note we now have to use cmpxchg_double_slab() for irq-safe slab_lock(), because
in some situations we don't take the list_lock, which would disable irqs.

Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
This commit is contained in:
Vlastimil Babka 2021-05-12 13:59:58 +02:00
parent a019d20162
commit 3406e91bce
1 changed files with 5 additions and 4 deletions
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9
mm/slub.c
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@ -2223,6 +2223,7 @@ static void deactivate_slab(struct kmem_cache *s, struct page *page,
enum slab_modes l = M_NONE, m = M_NONE;
void *nextfree, *freelist_iter, *freelist_tail;
int tail = DEACTIVATE_TO_HEAD;
unsigned long flags = 0;
struct page new;
struct page old;
@ -2298,7 +2299,7 @@ redo:
* that acquire_slab() will see a slab page that
* is frozen
*/
spin_lock(&n->list_lock);
spin_lock_irqsave(&n->list_lock, flags);
}
} else {
m = M_FULL;
@ -2309,7 +2310,7 @@ redo:
* slabs from diagnostic functions will not see
* any frozen slabs.
*/
spin_lock(&n->list_lock);
spin_lock_irqsave(&n->list_lock, flags);
}
}
@ -2326,14 +2327,14 @@ redo:
}
l = m;
if (!__cmpxchg_double_slab(s, page,
if (!cmpxchg_double_slab(s, page,
old.freelist, old.counters,
new.freelist, new.counters,
"unfreezing slab"))
goto redo;
if (lock)
spin_unlock(&n->list_lock);
spin_unlock_irqrestore(&n->list_lock, flags);
if (m == M_PARTIAL)
stat(s, tail);