From 25e4f9ada2f653b9aab60393aeda83d4f07684d1 Mon Sep 17 00:00:00 2001 From: Vlastimil Babka Date: Tue, 24 Aug 2021 09:58:59 +1000 Subject: [PATCH] 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. Link: https://lkml.kernel.org/r/20210805152000.12817-21-vbabka@suse.cz Signed-off-by: Vlastimil Babka Cc: Christoph Lameter Cc: David Rientjes Cc: Jann Horn Cc: Jesper Dangaard Brouer Cc: Joonsoo Kim Cc: Mel Gorman Cc: Mike Galbraith Cc: Pekka Enberg Cc: Sebastian Andrzej Siewior Cc: Thomas Gleixner Signed-off-by: Andrew Morton Signed-off-by: Stephen Rothwell --- mm/slub.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index ef36c94f27e2..00a96e9030e5 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -2209,6 +2209,7 @@ 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; @@ -2284,7 +2285,7 @@ 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; @@ -2295,7 +2296,7 @@ redo: * 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 @@ 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); -- 2.50.1