From 4da56b99d99e5a7df2b7f11e87bfea935f909732 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Mon, 4 Apr 2016 14:46:42 +0100 Subject: [PATCH] mm/vmap: Add a notifier for when we run out of vmap address space vmaps are temporary kernel mappings that may be of long duration. Reusing a vmap on an object is preferrable for a driver as the cost of setting up the vmap can otherwise dominate the operation on the object. However, the vmap address space is rather limited on 32bit systems and so we add a notification for vmap pressure in order for the driver to release any cached vmappings. The interface is styled after the oom-notifier where the callees are passed a pointer to an unsigned long counter for them to indicate if they have freed any space. v2: Guard the blocking notifier call with gfpflags_allow_blocking() v3: Correct typo in forward declaration and move to head of file Signed-off-by: Chris Wilson Cc: Andrew Morton Cc: David Rientjes Cc: Roman Peniaev Cc: Mel Gorman Cc: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org Acked-by: Andrew Morton # for inclusion via DRM Cc: Joonas Lahtinen Cc: Tvrtko Ursulin Link: http://patchwork.freedesktop.org/patch/msgid/1459777603-23618-3-git-send-email-chris@chris-wilson.co.uk Reviewed-by: Joonas Lahtinen --- include/linux/vmalloc.h | 4 ++++ mm/vmalloc.c | 27 +++++++++++++++++++++++++++ 2 files changed, 31 insertions(+) diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h index d1f1d338af20..8b51df3ab334 100644 --- a/include/linux/vmalloc.h +++ b/include/linux/vmalloc.h @@ -8,6 +8,7 @@ #include struct vm_area_struct; /* vma defining user mapping in mm_types.h */ +struct notifier_block; /* in notifier.h */ /* bits in flags of vmalloc's vm_struct below */ #define VM_IOREMAP 0x00000001 /* ioremap() and friends */ @@ -187,4 +188,7 @@ pcpu_free_vm_areas(struct vm_struct **vms, int nr_vms) #define VMALLOC_TOTAL 0UL #endif +int register_vmap_purge_notifier(struct notifier_block *nb); +int unregister_vmap_purge_notifier(struct notifier_block *nb); + #endif /* _LINUX_VMALLOC_H */ diff --git a/mm/vmalloc.c b/mm/vmalloc.c index fb42a5bffe47..12d27ac303ae 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -21,6 +21,7 @@ #include #include #include +#include #include #include #include @@ -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. @@ -363,6 +366,8 @@ static struct vmap_area *alloc_vmap_area(unsigned long size, BUG_ON(offset_in_page(size)); BUG_ON(!is_power_of_2(align)); + might_sleep_if(gfpflags_allow_blocking(gfp_mask)); + va = kmalloc_node(sizeof(struct vmap_area), gfp_mask & GFP_RECLAIM_MASK, node); if (unlikely(!va)) @@ -468,6 +473,16 @@ overflow: purged = 1; goto retry; } + + if (gfpflags_allow_blocking(gfp_mask)) { + unsigned long 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= to increase size.\n", size); @@ -475,6 +490,18 @@ overflow: return ERR_PTR(-EBUSY); } +int register_vmap_purge_notifier(struct notifier_block *nb) +{ + return blocking_notifier_chain_register(&vmap_notify_list, nb); +} +EXPORT_SYMBOL_GPL(register_vmap_purge_notifier); + +int unregister_vmap_purge_notifier(struct notifier_block *nb) +{ + return blocking_notifier_chain_unregister(&vmap_notify_list, nb); +} +EXPORT_SYMBOL_GPL(unregister_vmap_purge_notifier); + static void __free_vmap_area(struct vmap_area *va) { BUG_ON(RB_EMPTY_NODE(&va->rb_node));