Messages in this thread | | | Date | Fri, 30 May 2014 10:57:08 +0800 | Subject | Ask for help on the memory allocation for process shared mutex (resend with plain text) | From | yang ben <> |
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Dear experts,
I came across a memory/mutex issue. Would you kindly shed some light on it?
I use pthread_mutex_xxx API to protect processes in user space. Since it should be process shared, I allocated a shared memory to store pthread_mutex_t structure.
The shared memory is allocated using vmalloc_user() and mapped using remap_vmalloc_range() in driver. However, get_futex_key() will always return -EFAULT, because page_head->mapping==0.
futex.c (Linux-3.10.31) if (!page_head->mapping) { int shmem_swizzled = PageSwapCache(page_head); unlock_page(page_head); put_page(page_head); if (shmem_swizzled) goto again; return -EFAULT; }
Is there special requirement on the memory to store mutex? What's the correct way to allocate such memory in driver? Thanks in advance!
Regards, Ben
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