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Re: [PATCH] bio allocation failure due to bio_get_nr_vecs()

To: Bernd Schubert <bernd.schubert@xxxxxxxxxxxxxxxxxx>
Subject: Re: [PATCH] bio allocation failure due to bio_get_nr_vecs()
From: Jens Axboe <axboe@xxxxxxxxx>
Date: Fri, 11 May 2012 16:36:39 +0200
Cc: "linux-fsdevel@xxxxxxxxxxxxxxx" <linux-fsdevel@xxxxxxxxxxxxxxx>, linux-xfs@xxxxxxxxxxx, sandeen@xxxxxxxxxxx, Kent Overstreet <kent.overstreet@xxxxxxxxx>, Tejun Heo <tj@xxxxxxxxxx>
In-reply-to: <4FAD18D4.3090102@xxxxxxxxxxxxxxxxxx>
References: <jognqm$o21$1@xxxxxxxxxxxxxxx> <4FABF01E.7080303@xxxxxxxxxxxxxxxxxx> <4FAD18D4.3090102@xxxxxxxxxxxxxxxxxx>
On 05/11/2012 03:49 PM, Bernd Schubert wrote:
> The number of bio_get_nr_vecs() is passed down via bio_alloc() to
> bvec_alloc_bs(), which fails the bio allocation if
> nr_iovecs > BIO_MAX_PAGES. For the underlying caller this causes an
> unexpected bio allocation failure.
> Limiting to queue_max_segments() is not sufficient, as max_segments
> also might be very large.
> 
> bvec_alloc_bs(gfp_mask, nr_iovecs, ) => NULL when nr_iovecs  > BIO_MAX_PAGES
> bio_alloc_bioset(gfp_mask, nr_iovecs, ...)
> bio_alloc(GFP_NOIO, nvecs)
> xfs_alloc_ioend_bio()

Thanks, looks sane. Applied.

-- 
Jens Axboe

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