Date: Fri, 11 Oct 2002 11:14:37 -0700 (PDT) From: Matthew Dillon <dillon@apollo.backplane.com> To: David Schultz <dschultz@uclink.Berkeley.EDU> Cc: Peter Wemm <peter@wemm.org>, Sean Kelly <smkelly@zombie.org>, hackers@FreeBSD.ORG Subject: Re: swapoff? Message-ID: <200210111814.g9BIEbah040688@apollo.backplane.com> References: <20020713071911.GA1558@HAL9000.wox.org> <20020713073404.9869A3811@overcee.wemm.org> <20020713115746.GA2162@HAL9000.wox.org> <200207131636.g6DGaoqh081285@apollo.backplane.com> <20021007153845.GA371@HAL9000.homeunix.com> <200210072347.g97Nl3Zo049415@apollo.backplane.com> <20021008113614.GA319@HAL9000.homeunix.com> <200210081745.g98Hjkam078883@apollo.backplane.com> <20021011130154.GA16549@HAL9000.homeunix.com>
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:Thanks, your solution looks pretty good. I guess as part of the
:try_to_page_it_all_in, I'll want to call swap_pager_unswapped() on
:each page. Now I really wish I had noticed swap_pager_unswapped()
:earlier; it would have made my job much easier!
As long as you properly check and dirty the page you can get rid
of the backing swap.
:I'm worried that vm_proc_swapin_all() has a similar race with the
:swapout daemon. Presently I assume that my references to the
:UPAGES object and the associated pages remain valid after the
:faultin(), and that I can use swap_pager_freeswapspace() to free
:the correct metadata, instead of calling swap_pager_unswapped() on
:each page. Should just hold the process lock until the metadata
:are freed?
Hmm. Well, the proc lock is not held during vm_proc_swapin()
(but the PS_SWAPPINGIN flag is set). The proc lock is held during
vm_proc_swapout().
In your vm_proc_swapin_all() you seem to be doing the right thing
in regards to the mutexes and retry, and you have already marked
the device is SW_CLOSING so if something does get in there and
try to swap the process back in it shouldn't allocate swap you are
trying to free.
I think you may be ok.
-Matt
Matthew Dillon
<dillon@backplane.com>
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