From: Christoph Hellwig <hch@infradead.org>
To: Guoqing Jiang <guoqing.jiang@linux.dev>
Cc: song@kernel.org, linux-raid@vger.kernel.org,
jens@chianterastutte.eu, linux-block@vger.kernel.org
Subject: Re: [PATCH] raid1: ensure bio doesn't have more than BIO_MAX_VECS sectors
Date: Fri, 13 Aug 2021 08:49:04 +0100 [thread overview]
Message-ID: <YRYj8A+mDfAQBo/E@infradead.org> (raw)
In-Reply-To: <20210813060510.3545109-1-guoqing.jiang@linux.dev>
On Fri, Aug 13, 2021 at 02:05:10PM +0800, Guoqing Jiang wrote:
> From: Guoqing Jiang <jiangguoqing@kylinos.cn>
>
> We can't split bio with more than BIO_MAX_VECS sectors, otherwise the
> below call trace was triggered because we could allocate oversized
> write behind bio later.
>
> [ 8.097936] bvec_alloc+0x90/0xc0
> [ 8.098934] bio_alloc_bioset+0x1b3/0x260
> [ 8.099959] raid1_make_request+0x9ce/0xc50 [raid1]
Which bio_alloc_bioset is this? The one in alloc_behind_master_bio?
In which case I think you want to limit the reduction of max_sectors
to just the write behind case, and clearly document what is going on.
In general the size of a bio only depends on the number of vectors, not
the total I/O size. But alloc_behind_master_bio allocates new backing
pages using order 0 allocations, so in this exceptional case the total
size oes actually matter.
While we're at it: this huge memory allocation looks really deadlock
prone.
next prev parent reply other threads:[~2021-08-13 7:50 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-13 6:05 [PATCH] raid1: ensure bio doesn't have more than BIO_MAX_VECS sectors Guoqing Jiang
2021-08-13 7:49 ` Christoph Hellwig [this message]
2021-08-13 8:38 ` Guoqing Jiang
2021-08-14 7:55 ` Christoph Hellwig
2021-08-14 8:57 ` Ming Lei
2021-08-16 6:27 ` Guoqing Jiang
2021-08-16 7:13 ` Ming Lei
2021-08-16 9:37 ` Christoph Hellwig
2021-08-16 11:40 ` Ming Lei
2021-08-17 5:06 ` Christoph Hellwig
2021-08-17 12:32 ` Ming Lei
2021-09-24 15:34 ` Jens Stutte (Archiv)
2021-09-25 23:02 ` Guoqing Jiang
2021-08-13 9:27 ` kernel test robot
2021-08-13 10:12 ` kernel test robot
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