From: Christoph Hellwig <hch@infradead.org>
To: Shaohua Li <shli@fb.com>
Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
axboe@fb.com, Kernel-team@fb.com, "4.2+" <stable@vger.kernel.org>,
Ming Lei <ming.lei@canonical.com>
Subject: Re: [PATCH] block: don't make BLK_DEF_MAX_SECTORS too big
Date: Tue, 29 Mar 2016 14:18:33 -0700 [thread overview]
Message-ID: <20160329211833.GA18532@infradead.org> (raw)
In-Reply-To: <21cf85d32278bbe5acbc3def0a6db75db98a2670.1459269590.git.shli@fb.com>
On Tue, Mar 29, 2016 at 09:42:33AM -0700, Shaohua Li wrote:
> bio_alloc_bioset() allocates bvecs from bvec_slabs which can only
> allocate maximum 256 bvec (eg, 1M for 4k pages). We can't bump
> BLK_DEF_MAX_SECTORS to exceed this value otherwise bio_alloc_bioset will
> fail.
This might be true, but it's not a good enough reason. Request based
driver couldn't care less about the limits of bio_alloc_bioset.
It seems the bug is that somone (would be great to know whoe exactly)
passes a too large value to bio_alloc_bioset. And given that we still
have bio_add_page around for actually adding pages to a bio it seems
like the proper fix would be to simply clamp down the actual allocation
and segment limit inside bio_alloc_bioset. Which would also help to
eventually remove code doing just that in tons of callers.
next prev parent reply other threads:[~2016-03-29 21:18 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-29 16:42 [PATCH] block: don't make BLK_DEF_MAX_SECTORS too big Shaohua Li
2016-03-29 21:18 ` Christoph Hellwig [this message]
2016-03-29 22:01 ` Shaohua Li
2016-03-30 6:51 ` Christoph Hellwig
2016-03-30 16:50 ` Shaohua Li
2016-03-30 17:40 ` Christoph Hellwig
2016-03-31 0:52 ` Kent Overstreet
2016-03-30 1:39 ` Ming Lei
2016-03-30 2:27 ` Shaohua Li
2016-03-30 12:13 ` Ming Lei
2016-03-30 17:07 ` Shaohua Li
2016-03-31 0:49 ` Ming Lei
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