Messages in this thread | | | Date | Fri, 15 Oct 1999 22:47:37 +0200 | From | Manfred Spraul <> | Subject | Re: [PATCH] kanoj-mm17-2.3.21 kswapd vma scanning protection |
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Kanoj Sarcar wrote: > Explain ... who are the readers, and who are the writers? I think if you > are talking about a semaphore lock being held thru out swapout() in the > try_to_swap_out path, you are reduced to the same deadlock I just pointed > out. I was talking more about a monitor like approach here.
The lock is held thru out swapout(), but it is a shared lock: multiple swapper threads can own it. There should be no lock-up.
reader: swapper. Reentrancy is not a problem because it is a read-lock, ie shared. The implementation must starve exclusive waiters (ie a reader is allowed to continue even if a writer is waiting).
write: everyone who changes the vma list. These functions must not sleep while owning the ERESOURCE (IIRC the NT kernel name) exclusive.
I hope I have not overlocked a detail, Manfred
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