Hello. hugetlb_instantiation_mutex is an extremely heavy-weight lock whose days are numbered (hopefully). It exists primarily to arbitrate a race condition where n (n > 1) threads of execution race to satisfy the same page fault for a process. Even though only one hugetlb page is needed, if (n) are not available, the application can receive a bogus VM_FAULT_OOM.
Anyway, the hugetlb_instantiation_mutex approach has few friends around here, so rather than making the code rely more heavily upon it, perhaps you could focus you efforts on helping us remove it. On 7/23/07, Zhang, Yanmin <[EMAIL PROTECTED]> wrote:
Function hugetlb_fault needn't hold spinlock mm->page_table_lock, because when hugetlb_fault is called: 1) mm->mmap_sem is held already; 2) hugetlb_instantiation_mutex is held by hugetlb_fault, which prevents other threads/processes from entering this critical area. It's impossible for other threads/processes to change the page table now.
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