mm/vmalloc: eliminated the lock contention from twice to once

When allocating a new memory area where the mapping address range is
known, it is observed that the vmap_node->busy.lock is acquired twice.

The first acquisition occurs in the alloc_vmap_area() function when
inserting the vm area into the vm mapping red-black tree.  The second
acquisition occurs in the setup_vmalloc_vm() function when updating the
properties of the vm, such as flags and address, etc.

Combine these two operations together in alloc_vmap_area(), which improves
scalability when the vmap_node->busy.lock is contended.  By doing so, the
need to acquire the lock twice can also be eliminated to once.

With the above change, tested on intel sapphire rapids platform(224 vcpu),
a 4% performance improvement is gained on
stress-ng/pthread(https://github.com/ColinIanKing/stress-ng), which is the
stress test of thread creations.

Link: https://lkml.kernel.org/r/20240307021440.64967-1-rulin.huang@intel.com
Co-developed-by: "Chen, Tim C" <tim.c.chen@intel.com>
Signed-off-by: "Chen, Tim C" <tim.c.chen@intel.com>
Co-developed-by: "King, Colin" <colin.king@intel.com>
Signed-off-by: "King, Colin" <colin.king@intel.com>
Signed-off-by: rulinhuang <rulin.huang@intel.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Reviewed-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Wangyang Guo <wangyang.guo@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 61af431bb6b82f4c9df24f37076e27618f58c3c3..e30acfb2cd8ba2e8782b262b7b24ef37cdcd5c9b 100644 (file)
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -1926,15 +1926,26 @@ node_alloc(unsigned long size, unsigned long align,
        return va;
 }
 
+static inline void setup_vmalloc_vm(struct vm_struct *vm,
+       struct vmap_area *va, unsigned long flags, const void *caller)
+{
+       vm->flags = flags;
+       vm->addr = (void *)va->va_start;
+       vm->size = va->va_end - va->va_start;
+       vm->caller = caller;
+       va->vm = vm;
+}
+
 /*
  * Allocate a region of KVA of the specified size and alignment, within the
- * vstart and vend.
+ * vstart and vend. If vm is passed in, the two will also be bound.
  */
 static struct vmap_area *alloc_vmap_area(unsigned long size,
                                unsigned long align,
                                unsigned long vstart, unsigned long vend,
                                int node, gfp_t gfp_mask,
-                               unsigned long va_flags)
+                               unsigned long va_flags, struct vm_struct *vm,
+                               unsigned long flags, const void *caller)
 {
        struct vmap_node *vn;
        struct vmap_area *va;
@@ -1997,6 +2008,9 @@ retry:
        va->vm = NULL;
        va->flags = (va_flags | vn_id);
 
+       if (vm)
+               setup_vmalloc_vm(vm, va, flags, caller);
+
        vn = addr_to_node(va->va_start);
 
        spin_lock(&vn->busy.lock);
@@ -2574,7 +2588,8 @@ static void *new_vmap_block(unsigned int order, gfp_t gfp_mask)
        va = alloc_vmap_area(VMAP_BLOCK_SIZE, VMAP_BLOCK_SIZE,
                                        VMALLOC_START, VMALLOC_END,
                                        node, gfp_mask,
-                                       VMAP_RAM|VMAP_BLOCK);
+                                       VMAP_RAM|VMAP_BLOCK, NULL,
+                                       0, NULL);
        if (IS_ERR(va)) {
                kfree(vb);
                return ERR_CAST(va);
@@ -2931,7 +2946,8 @@ void *vm_map_ram(struct page **pages, unsigned int count, int node)
                struct vmap_area *va;
                va = alloc_vmap_area(size, PAGE_SIZE,
                                VMALLOC_START, VMALLOC_END,
-                               node, GFP_KERNEL, VMAP_RAM);
+                               node, GFP_KERNEL, VMAP_RAM,
+                               NULL, 0, NULL);
                if (IS_ERR(va))
                        return NULL;
 
@@ -3034,26 +3050,6 @@ void __init vm_area_register_early(struct vm_struct *vm, size_t align)
        kasan_populate_early_vm_area_shadow(vm->addr, vm->size);
 }
 
-static inline void setup_vmalloc_vm_locked(struct vm_struct *vm,
-       struct vmap_area *va, unsigned long flags, const void *caller)
-{
-       vm->flags = flags;
-       vm->addr = (void *)va->va_start;
-       vm->size = va->va_end - va->va_start;
-       vm->caller = caller;
-       va->vm = vm;
-}
-
-static void setup_vmalloc_vm(struct vm_struct *vm, struct vmap_area *va,
-                             unsigned long flags, const void *caller)
-{
-       struct vmap_node *vn = addr_to_node(va->va_start);
-
-       spin_lock(&vn->busy.lock);
-       setup_vmalloc_vm_locked(vm, va, flags, caller);
-       spin_unlock(&vn->busy.lock);
-}
-
 static void clear_vm_uninitialized_flag(struct vm_struct *vm)
 {
        /*
@@ -3090,14 +3086,12 @@ static struct vm_struct *__get_vm_area_node(unsigned long size,
        if (!(flags & VM_NO_GUARD))
                size += PAGE_SIZE;
 
-       va = alloc_vmap_area(size, align, start, end, node, gfp_mask, 0);
+       va = alloc_vmap_area(size, align, start, end, node, gfp_mask, 0, area, flags, caller);
        if (IS_ERR(va)) {
                kfree(area);
                return NULL;
        }
 
-       setup_vmalloc_vm(area, va, flags, caller);
-
        /*
         * Mark pages for non-VM_ALLOC mappings as accessible. Do it now as a
         * best-effort approach, as they can be mapped outside of vmalloc code.
@@ -4672,7 +4666,7 @@ retry:
 
                spin_lock(&vn->busy.lock);
                insert_vmap_area(vas[area], &vn->busy.root, &vn->busy.head);
-               setup_vmalloc_vm_locked(vms[area], vas[area], VM_ALLOC,
+               setup_vmalloc_vm(vms[area], vas[area], VM_ALLOC,
                                 pcpu_get_vm_areas);
                spin_unlock(&vn->busy.lock);
        }