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From: Vlastimil Babka <vbabka@suse.cz>
Date: Thu, 29 Jul 2021 15:21:17 +0200
Subject: [PATCH 20/35] 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>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
mm/slub.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2209,6 +2209,7 @@ static void deactivate_slab(struct kmem_
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;
@@ -2284,7 +2285,7 @@ static void deactivate_slab(struct kmem_
* 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;
@@ -2295,7 +2296,7 @@ static void deactivate_slab(struct kmem_
* slabs from diagnostic functions will not see
* any frozen slabs.
*/
- spin_lock(&n->list_lock);
+ spin_lock_irqsave(&n->list_lock, flags);
}
}
@@ -2312,14 +2313,14 @@ static void deactivate_slab(struct kmem_
}
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);
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