Messages in this thread | | | Date | Mon, 11 Oct 1999 19:01:12 -0400 (EDT) | From | Alexander Viro <> | Subject | Re: locking question: do_mmap(), do_munmap() |
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On Mon, 11 Oct 1999, Stephen C. Tweedie wrote:
> Hi, > > On Mon, 11 Oct 1999 20:02:40 +0200, Manfred Spraul > <manfreds@colorfullife.com> said: > > > What about something like a rw-semaphore which protects the vma list: > > vma-list modifiers [ie merge_segments(), insert_vm_struct() and > > do_munmap()] grab it exclusive, swapper grabs it "shared, starve > > exclusive". > > Deadlock. Process A tries to do an mmap on mm A, gets the exclusive > lock, tries to swap out from process B, and grabs mm B's shared lock. > Process B in the mean time is doing the same thing and has an exclusive > lock on mm B, and is trying to share-lock A. Whoops.
<looking at the places in question> insert_vm_struct doesn't allocate anything. Ditto for merge_segments In do_munmap() the area that should be protected (ripping the vmas from the list) doesn't allocate anything too. In the swapper we are protected from recursion, aren't we?
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