Re: IO errors after "block: remove bio_get_nr_vecs()"

[Artem S. Tashkinov]

On 2015-12-22 10:38, Kent Overstreet wrote:
> On Tue, Dec 22, 2015 at 05:26:12AM +0000, Junichi Nomura wrote:
> > On 12/22/15 12:59, Kent Overstreet wrote:
> > > reproduced it with 32 bit pae:
> > >
> > >> 1. Exclude memory above 4G line with boot param "max_addr=4G".
> > >
> > > doesn't work - max_addr=1G doesn't work either
> > >
> > >> 2. Disable highmem with "highmem=0".
> > >
> > > works!
> > >
> > >> 3. Try booting 64bit kernel.
> > >
> > > works
> >
> > blk_queue_bio() does split then bounce, which makes the segment
> > counting based on pages before bouncing and could go wrong.
> >
> > What do you think of a patch like this?
>
> Artem, can you give this patch a try?


This patch ostensibly fixes the issue - at least I cannot immediately 
reproduce it. You can count me in as "Tested-by: Artem S. Tashkinov"

> > --
> > Jun'ichi Nomura, NEC Corporation
> >
> > diff --git a/block/blk-core.c b/block/blk-core.c
> > index 5131993b..1d1c3c7 100644
> > --- a/block/blk-core.c
> > +++ b/block/blk-core.c
> > @@ -1689,8 +1689,6 @@ static blk_qc_t blk_queue_bio(struct 
> > request_queue *q, struct bio *bio)
> >  	struct request *req;
> >  	unsigned int request_count = 0;
> >
> > -	blk_queue_split(q, &bio, q->bio_split);
> > -
> >  	/*
> >  	 * low level driver can indicate that it wants pages above a
> >  	 * certain limit bounced to low memory (ie for highmem, or even
> > @@ -1698,6 +1696,8 @@ static blk_qc_t blk_queue_bio(struct 
> > request_queue *q, struct bio *bio)
> >  	 */
> >  	blk_queue_bounce(q, &bio);
> >
> > +	blk_queue_split(q, &bio, q->bio_split);
> > +
> >  	if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) {
> >  		bio->bi_error = -EIO;
> >  		bio_endio(bio);
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