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

["Artem S. Tashkinov" <t.artem@lycos.com>]

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);