Date: Sun, 26 Oct 2003 20:34:08 -0000 From: Jeff Roberson <jroberson@chesapeake.net> To: Alan Cox <alc@cs.rice.edu> Cc: cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/vm swap_pager.c Message-ID: <20031026153051.X43805-100000@mail.chesapeake.net> In-Reply-To: <20031026201944.GA20658@cs.rice.edu>
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On Sun, 26 Oct 2003, Alan Cox wrote: > With this change, you may see: > > lock order reversal > 1st 0xc24aab90 vm object (vm object) @ vm/swap_pager.c:1319 > 2nd 0xc070f180 swap_pager swhash (swap_pager swhash) @ vm/swap_pager.c:1832 > 3rd 0xc1036b90 vm object (vm object) @ vm/uma_core.c:876 > > This is also a false positive. The only vm object that is locked > after acquiring the "swap_pager swhash" mutex is one used internally > in UMA. We will never acquire this vm object's mutex followed by > the "swap_pager swhash" mutex. Does the swap_zone really need a backing object? This is just so the operation wont fail for lack of kva, right? Is this really necessary here? I thought we did it before so that we could allocate at interrupt time, since pages could be allocated, but kva could not. I doubt this code runs at real interrupt time anymore. > > Regards, > Alan > > On Sun, Oct 26, 2003 at 11:55:35AM -0800, Alan Cox wrote: > > alc 2003/10/26 11:55:35 PST > > > > FreeBSD src repository > > > > Modified files: > > sys/vm swap_pager.c > > Log: > > - Introduce and use a mutex synchronizing access to the swblock hash table. > > > > Revision Changes Path > > 1.234 +20 -4 src/sys/vm/swap_pager.c >
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