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    SubjectRe: [Bug #14141] order 2 page allocation failures in iwlagn
    Date
    On Thursday 01 October 2009, Rafael J. Wysocki wrote:
    > The following bug entry is on the current list of known regressions
    > introduced between 2.6.30 and 2.6.31. Please verify if it still should
    > be listed and let me know (either way).
    >
    > Bug-Entry : http://bugzilla.kernel.org/show_bug.cgi?id=14141
    > Subject : order 2 page allocation failures in iwlagn
    > Submitter : Frans Pop <elendil@planet.nl>
    > Date : 2009-09-06 7:40 (26 days old)
    > References : http://marc.info/?l=linux-kernel&m=125222287419691&w=4
    > Handled-By : Pekka Enberg <penberg@cs.helsinki.fi>

    I'm not sure about this.

    The error messages from failed allocations should now be a lot less as a
    result of this commit:
    commit f82a924cc88a5541df1d4b9d38a0968cd077a051
    Author: Reinette Chatre <reinette.chatre@intel.com>
    Date: Thu Sep 17 10:43:56 2009 -0700
    iwlwifi: reduce noise when skb allocation fails

    That commit is in mainline, and I'm not sure if it is important enough for
    a stable update (AFAICT it's not listed for 2.6.31.2).

    That commit is mostly cosmetic, but possibly the real regression is not in
    iwlagn but in the way memory is freed/defragmented. That aspect was also
    reported by Bartlomiej (#14016) and was extensively discussed (without a
    clear conclusion) here: http://lkml.org/lkml/2009/8/26/140.

    My own feeling is that Bartlomiej is correct and that something has changed
    since .29 and that on average we do have less higher order areas available
    after the system has been in use for some time, but I can't substantiate
    that. I do know that before .30 I had never seen the SKB allocation
    errors.

    Main problem is that it's hard to deliberately and reproducibly get the
    system in a state where the errors occur.

    I certainly do feel that the kernel should try to make sure higher order
    allocations remain possible during system use. They are not only needed
    shortly after boot: drivers can be loaded/unloaded at any time. OTOH Mel
    probably does have a point that really high order GFP_ATOMIC allocations
    by drivers make no sense [1].

    Anyway, I have no problems with this BR being closed.

    Cheers,
    FJP

    [1] <20090921133704.GO12726@csn.ul.ie>


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