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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 16:45:49 +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: <4FAD25B3.3050802@xxxxxxxxxxxxxxxxxx>
References: <jognqm$o21$1@xxxxxxxxxxxxxxx> <4FABF01E.7080303@xxxxxxxxxxxxxxxxxx> <4FAD18D4.3090102@xxxxxxxxxxxxxxxxxx> <4FAD23F7.2080605@xxxxxxxxx> <4FAD25B3.3050802@xxxxxxxxxxxxxxxxxx>
On 05/11/2012 04:44 PM, Bernd Schubert wrote:
> On 05/11/2012 04:36 PM, Jens Axboe wrote:
>> 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.
> Great, thanks! Should we CC linux-stable for commit
> 5abebfdd02450fa1349daacf242e70b3736581e3 and this one, as I got a hard
> kernel panic?

Yes, that's a good idea. I've ammended the commit now to include stable.

Jens Axboe

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