1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
|
From: Vlastimil Babka <vbabka@suse.cz>
Date: Thu, 29 Jul 2021 15:21:18 +0200
Subject: [PATCH 21/35] mm, slub: call deactivate_slab() without disabling irqs
The function is now safe to be called with irqs enabled, so move the calls
outside of irq disabled sections.
When called from ___slab_alloc() -> flush_slab() we have irqs disabled, so to
reenable them before deactivate_slab() we need to open-code flush_slab() in
___slab_alloc() and reenable irqs after modifying the kmem_cache_cpu fields.
But that means a IRQ handler meanwhile might have assigned a new page to
kmem_cache_cpu.page so we have to retry the whole check.
The remaining callers of flush_slab() are the IPI handler which has disabled
irqs anyway, and slub_cpu_dead() which will be dealt with in the following
patch.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
mm/slub.c | 24 +++++++++++++++++++-----
1 file changed, 19 insertions(+), 5 deletions(-)
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2765,8 +2765,8 @@ static void *___slab_alloc(struct kmem_c
freelist = c->freelist;
c->page = NULL;
c->freelist = NULL;
- deactivate_slab(s, page, freelist);
local_irq_restore(flags);
+ deactivate_slab(s, page, freelist);
new_slab:
@@ -2834,18 +2834,32 @@ static void *___slab_alloc(struct kmem_c
*/
goto return_single;
+retry_load_page:
+
local_irq_save(flags);
- if (unlikely(c->page))
- flush_slab(s, c);
+ if (unlikely(c->page)) {
+ void *flush_freelist = c->freelist;
+ struct page *flush_page = c->page;
+
+ c->page = NULL;
+ c->freelist = NULL;
+ c->tid = next_tid(c->tid);
+
+ local_irq_restore(flags);
+
+ deactivate_slab(s, flush_page, flush_freelist);
+
+ stat(s, CPUSLAB_FLUSH);
+
+ goto retry_load_page;
+ }
c->page = page;
goto load_freelist;
return_single:
- local_irq_save(flags);
deactivate_slab(s, page, get_freepointer(s, freelist));
- local_irq_restore(flags);
return freelist;
}
|
