[RFC 14/26] mm, slub: check new pages with restored irqs

From: Vlastimil Babka
Date: Mon May 24 2021 - 19:41:50 EST


Building on top of the previous patch, re-enable irqs before checking new
pages. alloc_debug_processing() is now called with enabled irqs so we need to
remove VM_BUG_ON(!irqs_disabled()); in check_slab() - there doesn't seem to be
a need for it anyway.

Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
---
mm/slub.c | 8 +++-----
1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/mm/slub.c b/mm/slub.c
index 78d7eb5be951..e092387b5932 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -968,8 +968,6 @@ static int check_slab(struct kmem_cache *s, struct page *page)
{
int maxobj;

- VM_BUG_ON(!irqs_disabled());
-
if (!PageSlab(page)) {
slab_err(s, page, "Not a valid slab page");
return 0;
@@ -2743,10 +2741,10 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
new_objects:

freelist = get_partial(s, gfpflags, node, &page);
+ local_irq_restore(flags);
if (freelist)
goto check_new_page;

- local_irq_restore(flags);
migrate_enable();
page = new_slab(s, gfpflags, node);
migrate_disable();
@@ -2757,7 +2755,6 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
return NULL;
}

- local_irq_save(flags);
/*
* No other reference to the page yet so we can
* muck around with it freely without cmpxchg
@@ -2772,7 +2769,6 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
if (kmem_cache_debug(s)) {
if (!alloc_debug_processing(s, page, freelist, addr)) {
/* Slab failed checks. Next slab needed */
- local_irq_restore(flags);
goto new_slab;
} else {
/*
@@ -2790,6 +2786,7 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
*/
goto return_single;

+ local_irq_save(flags);
if (unlikely(c->page))
flush_slab(s, c);
c->page = page;
@@ -2798,6 +2795,7 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,

return_single:

+ local_irq_save(flags);
if (unlikely(c->page))
flush_slab(s, c);
c->page = page;
--
2.31.1