一、分区伙伴分配器物理分配页核心函数 __alloc_pages_nodemask
Linux 内核中 , " 分区伙伴分配器 " 有多种 物理页分配函数 , 所有的 函数 都会调用 __alloc_pages_nodemask 函数 , 该函数是 物理页分配 的 核心函数 ;
__alloc_pages_nodemask 函数 定义在 Linux 内核源码的 linux-4.12\mm\page_alloc.c#4003 位置 , 函数原型如下 :
/*
* This is the 'heart' of the zoned buddy allocator.
*/
struct page *
__alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order,
struct zonelist *zonelist, nodemask_t *nodemask)
源码路径 : linux-4.12\mm\page_alloc.c#4003
二、__alloc_pages_nodemask 函数完整源码
/*
* This is the 'heart' of the zoned buddy allocator.
*/
struct page *
__alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order,
struct zonelist *zonelist, nodemask_t *nodemask)
{
struct page *page;
unsigned int alloc_flags = ALLOC_WMARK_LOW;
gfp_t alloc_mask = gfp_mask; /* The gfp_t that was actually used for allocation */
struct alloc_context ac = {
};
gfp_mask &= gfp_allowed_mask;
if (!prepare_alloc_pages(gfp_mask, order, zonelist, nodemask, &ac, &alloc_mask, &alloc_flags))
return NULL;
finalise_ac(gfp_mask, order, &ac);
/* First allocation attempt */
page = get_page_from_freelist(alloc_mask, order, alloc_flags, &ac);
if (likely(page))
goto out;
/*
* Apply scoped allocation constraints. This is mainly about GFP_NOFS
* resp. GFP_NOIO which has to be inherited for all allocation requests
* from a particular context which has been marked by
* memalloc_no{fs,io}_{save,restore}.
*/
alloc_mask = current_gfp_context(gfp_mask);
ac.spread_dirty_pages = false;
/*
* Restore the original nodemask if it was potentially replaced with
* &cpuset_current_mems_allowed to optimize the fast-path attempt.
*/
if (unlikely(ac.nodemask != nodemask))
ac.nodemask = nodemask;
page = __alloc_pages_slowpath(alloc_mask, order, &ac);
out:
if (memcg_kmem_enabled() && (gfp_mask & __GFP_ACCOUNT) && page &&
unlikely(memcg_kmem_charge(page, gfp_mask, order) != 0)) {
__free_pages(page, order);
page = NULL;
}
if (kmemcheck_enabled && page)
kmemcheck_pagealloc_alloc(page, order, gfp_mask);
trace_mm_page_alloc(page, order, alloc_mask, ac.migratetype);
return page;
}
源码路径 : linux-4.12\mm\page_alloc.c#4003