nested page-faulting of user-space address in Linux

Posted by shankar on Stack Overflow See other posts from Stack Overflow or by shankar
Published on 2010-03-19T13:27:39Z Indexed on 2010/03/19 13:31 UTC
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linux-kernel

Hi,

I would like to know if it is functionally wrong to page-fault a user-space address when kernel is running fault-handler to bring in a user-page.

OS is Linux 2.6.30

Assume that both user-addresses are valid ( falling within vma , rw permission ) for the task.

When I check the kernel code, i find that the kernel does not mind the nested fault if the faulted-addresses are valid and the fault did not occur in atomic-context or in irq handler.

(I dont think the answer is cpu-specific, but I would add that i am interested in arm and mips ).

eg : The scenario can happen if I print stack-data from page-fault handler.

            thanks
              shankar

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