On 23/02/16 11:52, Chris Wilson wrote:
On Tue, Feb 23, 2016 at 11:38:02AM +0000, Chris Wilson wrote:
Indeed, we would need a new notifier, pretty much for the sole use of
32b. Grr, that will be a nuisance.
Core changes:
diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
index d1f1d338af20..542a91c2785f 100644
--- a/include/linux/vmalloc.h
+++ b/include/linux/vmalloc.h
@@ -187,4 +187,8 @@ pcpu_free_vm_areas(struct vm_struct **vms, int nr_vms)
#define VMALLOC_TOTAL 0UL
#endif
+struct notitifer_block;
+int register_vmap_notifier(struct notifier_block *nb);
+int unregister_vmap_notifier(struct notifier_block *nb);
+
#endif /* _LINUX_VMALLOC_H */
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index fb42a5bffe47..0735d82444f7 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -21,6 +21,7 @@
#include <linux/debugobjects.h>
#include <linux/kallsyms.h>
#include <linux/list.h>
+#include <linux/notifier.h>
#include <linux/rbtree.h>
#include <linux/radix-tree.h>
#include <linux/rcupdate.h>
@@ -344,6 +345,8 @@ static void __insert_vmap_area(struct vmap_area *va)
static void purge_vmap_area_lazy(void);
+static BLOCKING_NOTIFIER_HEAD(vmap_notify_list);
+
/*
* Allocate a region of KVA of the specified size and alignment, within the
* vstart and vend.
@@ -356,6 +359,7 @@ static struct vmap_area *alloc_vmap_area(unsigned long size,
struct vmap_area *va;
struct rb_node *n;
unsigned long addr;
+ unsigned long freed;
int purged = 0;
struct vmap_area *first;
@@ -468,6 +472,12 @@ overflow:
purged = 1;
goto retry;
}
+ freed = 0;
+ blocking_notifier_call_chain(&vmap_notify_list, 0, &freed);
+ if (freed > 0) {
+ purged = 0;
+ goto retry;
+ }
if (printk_ratelimit())
pr_warn("vmap allocation for size %lu failed: "
"use vmalloc=<size> to increase size.\n", size);
@@ -475,6 +485,18 @@ overflow:
return ERR_PTR(-EBUSY);
}
+int register_vmap_notifier(struct notifier_block *nb)
+{
+ return blocking_notifier_chain_register(&vmap_notify_list, nb);
+}
+EXPORT_SYMBOL_GPL(register_vmap_notifier);
+
+int unregister_vmap_notifier(struct notifier_block *nb)
+{
+ return blocking_notifier_chain_unregister(&vmap_notify_list, nb);
+}
+EXPORT_SYMBOL_GPL(unregister_vmap_notifier);
+
static void __free_vmap_area(struct vmap_area *va)
{
BUG_ON(RB_EMPTY_NODE(&va->rb_node));
That doesn't look too horrendous. Names?
Downside is new deadlock opportunity so GEM callers to vmap would have
to release the struct mutex.
register_oovmap_notifier
register_vmap_nospace_notifier?
register_vmap_purge_notifier?
register_vmap_shrinker ?
And the 64k question, how to sell it?
Not sure, maybe with numbers showing that caching the vmapping helps us
significantly?
Regards,
Tvrtko
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