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

[Vlastimil Babka]

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