On Sun, Sep 20, 2015 at 5:56 AM, Oleg Nesterov <oleg@xxxxxxxxxx> wrote:
In this case the workqueue thread will block.
What workqueue thread?
pagefault_out_of_memory ->
out_of_memory ->
oom_kill_process
as far as I can tell, this can be called by any task. Now, that
pagefault case should only happen when the page fault comes from user
space, but we also have
__alloc_pages_slowpath ->
__alloc_pages_may_oom ->
out_of_memory ->
oom_kill_process
which can be called from just about any context (but atomic
allocations will never get here, so it can schedule etc).
So what's your point? Explain again just how do you guarantee that you
can take the mmap_sem.
Linus
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Would it be a cleaner design in general to require all
threads to completely exit kernel space before being terminated?
Possibly expedited by noticing fatal signals and riding the EINTR
rocket back up the stack?
My two cents: If we do that we won't have to worry about
fatally wounded tasks slipping into a coma before they cough up
any semaphores or locks.