From: Theodore Tso <tytso@mit.edu>
To: Jens Axboe <jens.axboe@oracle.com>
Cc: Nikanth Karthikesan <knikanth@suse.de>,
Neil Brown <neilb@suse.de>,
linux-kernel@vger.kernel.org,
Chris Mason <chris.mason@oracle.com>,
Andrew Morton <akpm@linux-foundation.org>,
Dave Kleikamp <shaggy@austin.ibm.com>,
xfs-masters@oss.sgi.com
Subject: Re: [PATCH 0/6] Handle bio_alloc failure
Date: Tue, 14 Apr 2009 14:33:51 -0400 [thread overview]
Message-ID: <20090414183351.GK955@mit.edu> (raw)
In-Reply-To: <20090414182049.GI5178@kernel.dk>
On Tue, Apr 14, 2009 at 08:20:49PM +0200, Jens Axboe wrote:
>
> It's a bio_alloc() guarantee, it uses a mempool backing. And if you use
> a mempool backing, any allocation that can wait will always be
> satisfied.
>
Am I missing something? I don't see anything in
include/linux/mempool.h or mm/mempool.c, or in block/blk-core.c or
include/linux/bio.h which documents that GFP_WAIT implies that
bio_alloc() will always succeed.
My concern is that at some point in the future, someone either in the
block device layer or in mm/mempool.c will consider this an
implementation detail, and all of sudden calls to bio_alloc() with
GFP_WAIT will start failing and the resulting hilarty which ensues
won't be easily predicted by the developer making this change.
Regards,
- Ted
next prev parent reply other threads:[~2009-04-14 18:35 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-04-14 11:06 [PATCH 0/6] Handle bio_alloc failure Nikanth Karthikesan
2009-04-14 11:18 ` Jens Axboe
2009-04-14 11:41 ` Nikanth Karthikesan
2009-04-14 18:16 ` Theodore Tso
2009-04-14 18:20 ` Jens Axboe
2009-04-14 18:33 ` Theodore Tso [this message]
2009-04-14 18:40 ` Jens Axboe
2009-04-14 18:46 ` Andrew Morton
2009-04-15 8:46 ` Nick Piggin
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