[PATCH v4 15/35] mm, slub: restore irqs around calling new_slab()

From: Vlastimil Babka
Date: Thu Aug 05 2021 - 11:24:28 EST


allocate_slab() currently re-enables irqs before calling to the page allocator.
It depends on gfpflags_allow_blocking() to determine if it's safe to do so.
Now we can instead simply restore irq before calling it through new_slab().
The other caller early_kmem_cache_node_alloc() is unaffected by this.

Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
---
mm/slub.c | 8 ++------
1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/mm/slub.c b/mm/slub.c
index 868a782b6f62..9350ff5110a0 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1792,9 +1792,6 @@ static struct page *allocate_slab(struct kmem_cache *s, gfp_t flags, int node)

flags &= gfp_allowed_mask;

- if (gfpflags_allow_blocking(flags))
- local_irq_enable();
-
flags |= s->allocflags;

/*
@@ -1853,8 +1850,6 @@ static struct page *allocate_slab(struct kmem_cache *s, gfp_t flags, int node)
page->frozen = 1;

out:
- if (gfpflags_allow_blocking(flags))
- local_irq_disable();
if (!page)
return NULL;

@@ -2782,16 +2777,17 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
goto check_new_page;
}

+ local_irq_restore(flags);
put_cpu_ptr(s->cpu_slab);
page = new_slab(s, gfpflags, node);
c = get_cpu_ptr(s->cpu_slab);

if (unlikely(!page)) {
- local_irq_restore(flags);
slab_out_of_memory(s, gfpflags, node);
return NULL;
}

+ local_irq_save(flags);
if (c->page)
flush_slab(s, c);

--
2.32.0