From: Ming Lei <ming.lei@redhat.com>
To: Christoph Hellwig <hch@lst.de>
Cc: Jens Axboe <axboe@kernel.dk>, Satya Tangirala <satyat@google.com>,
Chaitanya Kulkarni <Chaitanya.Kulkarni@wdc.com>,
John Stultz <john.stultz@linaro.org>,
linux-block@vger.kernel.org
Subject: Re: [PATCH 4/4] block: memory allocations in bounce_clone_bio must not fail
Date: Thu, 25 Feb 2021 10:21:55 +0800 [thread overview]
Message-ID: <YDcJw/5u8FG/0g0E@T590> (raw)
In-Reply-To: <20210224161236.GA9127@lst.de>
On Wed, Feb 24, 2021 at 05:12:36PM +0100, Christoph Hellwig wrote:
> On Wed, Feb 24, 2021 at 07:19:52PM +0800, Ming Lei wrote:
> > > if (bio_is_passthrough(bio_src))
> > > - bio = bio_kmalloc(GFP_NOIO, bio_segments(bio_src));
> > > + bio = bio_kmalloc(GFP_NOIO | __GFP_NOFAIL,
> > > + bio_segments(bio_src));
> >
> > bio_kmalloc() still may fail if bio_segments(bio_src) is > UIO_MAXIOV.
>
> Yes, but bio_kmalloc is what is used to allocate the passthrough
> requests to start with, so we'd not even make it here.
The original bio_kmalloc() may start with allowed nr_iovecs , but
later more pages are retrieved from iov_iter and added to the bio,
see bio_map_user_iov(). Then bounce_clone_bio() will see too big
bio_segments(bio_src) to be held in UIO_MAXIOV vecs.
This behavior is similar with blkdev_direct_IO().
--
Ming
next prev parent reply other threads:[~2021-02-25 2:23 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-24 7:24 bio_kmalloc related fixes for 5.12 Christoph Hellwig
2021-02-24 7:24 ` [PATCH 1/4] block-crypto-fallback: use a bio_set for splitting bios Christoph Hellwig
2021-02-24 16:17 ` Satya Tangirala
2021-02-24 23:23 ` Eric Biggers
2021-02-24 7:24 ` [PATCH 2/4] block: fix bounce_clone_bio for passthrough bios Christoph Hellwig
2021-02-24 20:30 ` Chaitanya Kulkarni
2021-02-24 7:24 ` [PATCH 3/4] block: remove the gfp_mask argument to bounce_clone_bio Christoph Hellwig
2021-02-24 20:30 ` Chaitanya Kulkarni
2021-02-24 7:24 ` [PATCH 4/4] block: memory allocations in bounce_clone_bio must not fail Christoph Hellwig
2021-02-24 11:19 ` Ming Lei
2021-02-24 16:12 ` Christoph Hellwig
2021-02-25 2:21 ` Ming Lei [this message]
2021-02-24 20:32 ` Chaitanya Kulkarni
2021-02-24 15:55 ` bio_kmalloc related fixes for 5.12 Jens Axboe
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