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    SubjectRe: [PATCH 0/6] Handle bio_alloc failure
    On Tue, Apr 14, 2009 at 05:11:19PM +0530, Nikanth Karthikesan wrote:
    > On Tuesday 14 April 2009 16:48:38 Jens Axboe wrote:
    > >
    > > It will not fail as long as __GFP_WAIT is set, which it is for all 6 of
    > > your patches.

    Um, before we take out the checks, can we please make sure this is a
    guaranteed, documented behaviour? In include/linux/page_alloc.h,
    __GFP_NOFAIL is documented as "will never fail", but it says
    absolutely nothing about __GFP_WAIT.

    Some day, someone will create a static checker that will flag warnings
    when people fail to check for allocation failures, and it would be
    good if the formal semantics for __GFP_WAIT, and hence for GFP_NOFS,
    GFP_KERNEL, and GFP_USER, et. al. are defined.

    We have code in fs/jbd2/transaction.c that calls kzalloc with
    GFP_NOFS|__GFP_NOFAIL, since I and many other people had the
    assumption that without __GFP_NOFAIL, an GFP_NOFS allocation could
    very well fail.

    Or is this special-case behaviour which bio_alloc() guarantees, but
    not necessarily any other allocation function?

    - Ted

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      Last update: 2009-04-14 20:19    [W:0.023 / U:11.168 seconds]
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