@@ -815,6 +815,15 @@ static inline int PageSlabPfmemalloc(str
return PageActive(page);
}
+/*
+ * A version of PageSlabPfmemalloc() for opportunistic checks where the page
+ * might have been freed under us and not be a PageSlab anymore.
+ */
+static inline int __PageSlabPfmemalloc(struct page *page)
+{
+ return PageActive(page);
+}
+
static inline void SetPageSlabPfmemalloc(struct page *page)
{
VM_BUG_ON_PAGE(!PageSlab(page), page);
@@ -2607,6 +2607,19 @@ static inline bool pfmemalloc_match(stru
}
/*
+ * A variant of pfmemalloc_match() that tests page flags without asserting
+ * PageSlab. Intended for opportunistic checks before taking a lock and
+ * rechecking that nobody else freed the page under us.
+ */
+static inline bool pfmemalloc_match_unsafe(struct page *page, gfp_t gfpflags)
+{
+ if (unlikely(__PageSlabPfmemalloc(page)))
+ return gfp_pfmemalloc_allowed(gfpflags);
+
+ return true;
+}
+
+/*
* Check the page->freelist of a page and either transfer the freelist to the
* per cpu freelist or deactivate the page.
*
@@ -2668,8 +2681,9 @@ static void *___slab_alloc(struct kmem_c
stat(s, ALLOC_SLOWPATH);
- local_irq_save(flags);
- page = c->page;
+reread_page:
+
+ page = READ_ONCE(c->page);
if (!page) {
/*
* if the node is not online or has no normal memory, just
@@ -2678,6 +2692,11 @@ static void *___slab_alloc(struct kmem_c
if (unlikely(node != NUMA_NO_NODE &&
!node_isset(node, slab_nodes)))
node = NUMA_NO_NODE;
+ local_irq_save(flags);
+ if (unlikely(c->page)) {
+ local_irq_restore(flags);
+ goto reread_page;
+ }
goto new_slab;
}
redo:
@@ -2692,8 +2711,7 @@ redo:
goto redo;
} else {
stat(s, ALLOC_NODE_MISMATCH);
- deactivate_slab(s, page, c->freelist, c);
- goto new_slab;
+ goto deactivate_slab;
}
}
@@ -2702,12 +2720,15 @@ redo:
* PFMEMALLOC but right now, we are losing the pfmemalloc
* information when the page leaves the per-cpu allocator
*/
- if (unlikely(!pfmemalloc_match(page, gfpflags))) {
- deactivate_slab(s, page, c->freelist, c);
- goto new_slab;
- }
+ if (unlikely(!pfmemalloc_match_unsafe(page, gfpflags)))
+ goto deactivate_slab;
- /* must check again c->freelist in case of cpu migration or IRQ */
+ /* must check again c->page in case IRQ handler changed it */
+ local_irq_save(flags);
+ if (unlikely(page != c->page)) {
+ local_irq_restore(flags);
+ goto reread_page;
+ }
freelist = c->freelist;
if (freelist)
goto load_freelist;
@@ -2723,6 +2744,9 @@ redo:
stat(s, ALLOC_REFILL);
load_freelist:
+
+ lockdep_assert_irqs_disabled();
+
/*
* freelist is pointing to the list of objects to be used.
* page is pointing to the page from which the objects are obtained.
@@ -2734,11 +2758,23 @@ load_freelist:
local_irq_restore(flags);
return freelist;
+deactivate_slab:
+
+ local_irq_save(flags);
+ if (page != c->page) {
+ local_irq_restore(flags);
+ goto reread_page;
+ }
+ deactivate_slab(s, page, c->freelist, c);
+
new_slab:
+ lockdep_assert_irqs_disabled();
+
if (slub_percpu_partial(c)) {
page = c->page = slub_percpu_partial(c);
slub_set_percpu_partial(c, page);
+ local_irq_restore(flags);
stat(s, CPU_PARTIAL_ALLOC);
goto redo;
}