Date: Tue, 2 Mar 1999 11:37:04 -0600 From: Alan Cox <alc@cs.rice.edu> To: Bruce Evans <bde@zeta.org.au> Cc: current@freebsd.org Subject: Re: lockmgr panic with mmap() Message-ID: <19990302113704.B90473@nonpc.cs.rice.edu> In-Reply-To: <199903021141.WAA03136@godzilla.zeta.org.au>; from Bruce Evans on Tue, Mar 02, 1999 at 10:41:46PM %2B1100 References: <199903021141.WAA03136@godzilla.zeta.org.au>
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On Tue, Mar 02, 1999 at 10:41:46PM +1100, Bruce Evans wrote: > > Doesn't it modify the map indirectly vi subyte()? I think it wants > to prevent modifications, but this is impossible. > Bear with me, I'll have to split some hairs... We're only interested in whether mincore directly changes the vm_map, literally modifying a vm_map_entry, etc. subyte is writing to memory, not a vm_map_entry. subyte is only indirectly changing the map because a page fault occurs. That page fault *is* (frequently) changing the map, and we're deadlocking when it attempts to acquire the write lock on the map. Basically, what I believe that you suggested yesterday, that mincore release the lock around the subyte is correct. Code will appear shortly... Alan To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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