Yes access_process_vm down_writes the mmap_sem. However; it can only read
and write to existing user pages. As long as it doesn't delete any of them
its not a problem. It won't cause a dead lock or panic during the core dump
processing if this happens.
The only process I know that could honestly use this ptrace function is GDB
doing live debugging.
> Why shouldn't you take the semaphore as before in elf_core_dump, if you
> know that no suspended process has it - which you do if you hold it
> while suspending them?
For Ia64 those down_writes are just a pain. If a user application is
crashing because someone is being rude with GDB corrupting its user pages
then I don't think its worth the hassle of protecting the core dumped user
page mm data from being messed up by a GDB user.
I would like to leave the down_write out of elf_core_dump, but it could be
put back if its felt that its needed.
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