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#author("2025-10-24T12:42:27+09:00","default:guest","guest") #author("2025-10-24T12:42:37+09:00","default:guest","guest") *参照元 [#s763da5f] #backlinks *説明 [#m9bed659] -パス: [[linux-5.15/]] -パス: [[linux-5.15/mm/page_alloc.c]] -FIXME: これは何？ --説明 **引数 [#j02f0876] -gfp_t gfp -- -unsigned int order -- -int preferred_nid -- -nodemask_t *nodemask -- --[[linux-5.15/nodemask_t]] **返り値 [#yc175a6b] -struct page * -- --[[linux-5.15/page]] **参考 [#rbe7a4c6] *実装 [#t5db9103] /* * This is the 'heart' of the zoned buddy allocator. */ struct page *__alloc_pages(gfp_t gfp, unsigned int order, int preferred_nid, nodemask_t *nodemask) { struct page *page; unsigned int alloc_flags = ALLOC_WMARK_LOW; gfp_t alloc_gfp; /* The gfp_t that was actually used for allocation */ struct alloc_context ac = { }; /* * There are several places where we assume that the order value is sane * so bail out early if the request is out of bound. */ if (unlikely(order >= MAX_ORDER)) { WARN_ON_ONCE(!(gfp & __GFP_NOWARN)); return NULL; } - --[[linux-5.15/page]] --[[linux-5.15/gfp_t]] --[[linux-5.15/alloc_context]] --[[linux-5.15/unlikely()]] --[[linux-5.15/WARN_ON_ONCE()]] gfp &= gfp_allowed_mask; /* * 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}. And PF_MEMALLOC_PIN which ensures * movable zones are not used during allocation. */ gfp = current_gfp_context(gfp); alloc_gfp = gfp; if (!prepare_alloc_pages(gfp, order, preferred_nid, nodemask, &ac, &alloc_gfp, &alloc_flags)) return NULL; - --[[linux-5.15/current_gfp_context()]] --[[linux-5.15/prepare_alloc_pages()]] /* * Forbid the first pass from falling back to types that fragment * memory until all local zones are considered. */ alloc_flags |= alloc_flags_nofragment(ac.preferred_zoneref->zone, gfp); /* First allocation attempt */ page = get_page_from_freelist(alloc_gfp, order, alloc_flags, &ac); if (likely(page)) goto out; alloc_gfp = gfp; ac.spread_dirty_pages = false; - --[[linux-5.15/alloc_flags_nofragment()]] --[[linux-5.15/get_page_from_freelist()]] --[[linux-5.15/likely()]] /* * Restore the original nodemask if it was potentially replaced with * &cpuset_current_mems_allowed to optimize the fast-path attempt. */ ac.nodemask = nodemask; page = __alloc_pages_slowpath(alloc_gfp, order, &ac); out: if (memcg_kmem_enabled() && (gfp & __GFP_ACCOUNT) && page && unlikely(__memcg_kmem_charge_page(page, gfp, order) != 0)) { __free_pages(page, order); page = NULL; } - --[[linux-5.15/__alloc_pages_slowpath()]] --[[linux-5.15/memcg_kmem_enabled()]] --[[linux-5.15/unlikely()]] --[[linux-5.15/__memcg_kmem_charge_page()]] --[[linux-5.15/__free_pages()]] trace_mm_page_alloc(page, order, alloc_gfp, ac.migratetype); return page; } EXPORT_SYMBOL(__alloc_pages); - --[[linux-5.15/trace_mm_page_alloc()]] --[[linux-5.15/EXPORT_SYMBOL()]] *コメント [#g1472970]
