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slub: Keep track of whether slub is on the per-node partial list

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Now we rely on the "frozen" bit to see if we should manipulate the
slab->slab_list, which will be changed in the following patch.

Instead we introduce another way to keep track of whether slub is on
the per-node partial list, here we reuse the PG_workingset bit.

We have to use the atomic set_bit() and clear_bit() variants and change
slab_unlock() to bit_spin_unlock() because when cmpxchg is not available
and PG_lock is used, there may be concurrent operations on the two bits.
Thanks to Mark Brown for reporting a hang and testing of a previous
version where the non-atomic operations were used.

Suggested-by: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Tested-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Reviewed-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
This commit is contained in:
Chengming Zhou 2023-11-02 03:23:24 +00:00 committed by Vlastimil Babka
parent 43c4c34914
commit 8a399e2f60
1 changed files with 23 additions and 1 deletions
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24
mm/slub.c
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@ -522,7 +522,7 @@ static __always_inline void slab_unlock(struct slab *slab)
struct page *page = slab_page(slab);
VM_BUG_ON_PAGE(PageTail(page), page);
__bit_spin_unlock(PG_locked, &page->flags);
bit_spin_unlock(PG_locked, &page->flags);
}
static inline bool
@ -2116,6 +2116,25 @@ static void discard_slab(struct kmem_cache *s, struct slab *slab)
free_slab(s, slab);
}
/*
* SLUB reuses PG_workingset bit to keep track of whether it's on
* the per-node partial list.
*/
static inline bool slab_test_node_partial(const struct slab *slab)
{
return folio_test_workingset((struct folio *)slab_folio(slab));
}
static inline void slab_set_node_partial(struct slab *slab)
{
set_bit(PG_workingset, folio_flags(slab_folio(slab), 0));
}
static inline void slab_clear_node_partial(struct slab *slab)
{
clear_bit(PG_workingset, folio_flags(slab_folio(slab), 0));
}
/*
* Management of partially allocated slabs.
*/
@ -2127,6 +2146,7 @@ __add_partial(struct kmem_cache_node *n, struct slab *slab, int tail)
list_add_tail(&slab->slab_list, &n->partial);
else
list_add(&slab->slab_list, &n->partial);
slab_set_node_partial(slab);
}
static inline void add_partial(struct kmem_cache_node *n,
@ -2141,6 +2161,7 @@ static inline void remove_partial(struct kmem_cache_node *n,
{
lockdep_assert_held(&n->list_lock);
list_del(&slab->slab_list);
slab_clear_node_partial(slab);
n->nr_partial--;
}
@ -4833,6 +4854,7 @@ static int __kmem_cache_do_shrink(struct kmem_cache *s)
if (free == slab->objects) {
list_move(&slab->slab_list, &discard);
slab_clear_node_partial(slab);
n->nr_partial--;
dec_slabs_node(s, node, slab->objects);
} else if (free <= SHRINK_PROMOTE_MAX)