lkml.org 
[lkml]   [1999]   [Oct]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: locking question: do_mmap(), do_munmap()


    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?


    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.rutgers.edu
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2005-03-22 13:54    [W:0.021 / U:1.940 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site