Re: "swap_free: Unused swap offset entry 00000100" but no crash?

From: Marcelo Tosatti (
Date: 07/27/04

  • Next message: Jens Axboe: "Re: [Repost] IDE error 2.6.7-rc3-mm2 and 2.6.8-rc1-mm1"
    Date:	Tue, 27 Jul 2004 15:58:59 -0300
    To: Robin Holt <>

    On Tue, Jul 27, 2004 at 07:53:04AM -0500, Robin Holt wrote:
    > On Tue, Jul 27, 2004 at 10:30:02PM +1000, Keith Owens wrote:
    > > On Tue, 27 Jul 2004 02:21:54 +0200,
    > > Marcin Owsiany <> wrote:
    > > > kernel: swap_free: Unused swap offset entry 00000100
    > > >Also, I would be grateful if someone could explain what is that number in the
    > > >message supposed to be? An address?
    > >
    > > It is a swap partition number, but I doubt that you have 256 swap
    > > partitions in your system. Single bit set in a word that is meant to
    > > be 0, most likely to be caused by a hardware single bit error. Run
    > > memtest, burn86 or other memory verification checks.
    > >
    > I remember a race condition I thought was possible, but couldn't exactly
    > pin down the exact sequence. Give me a chance to dig through some of
    > my notes and see what I come across.

    Would love to hear more details about this.

    > I think I could understand this if there two messages with each invocation,
    > but not with one.
    > Marcin, you have a process with a Page Table Entry which indicates it is
    > pointing to a page which has been swapped out to block 0 of swap device
    > 256. This is probably caused by a problem in the kernel. You can certainly
    > run memtest et al. If you don't find anything, I would assume the problem
    > is in the kernel.

    Marcin, please run the memtest86 and report back.

    > Most of the code in the area you would be affected by has changed
    > drastically in the 2.6 kernel.

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