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Date: Tue, 22 Dec 2015 10:52:37 +0500
From: "Artem S. Tashkinov" <t.artem@lycos.com>
To: Kent Overstreet <kent.overstreet@gmail.com>
Cc: Junichi Nomura <j-nomura@ce.jp.nec.com>, Tejun Heo <tj@kernel.org>,
        "Artem S. Tashkinov" <t.artem@mailcity.com>,
        Christoph Hellwig <hch@lst.de>, Ming Lin <ming.l@ssi.samsung.com>,
        Jens Axboe <axboe@fb.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Steven Whitehouse <swhiteho@redhat.com>,
        IDE-ML <linux-ide@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Ming Lei <tom.leiming@gmail.com>
Subject: Re: IO errors after "block: remove =?UTF-8?Q?bio=5Fget=5Fnr=5Fvec?=
 =?UTF-8?Q?s=28=29=22?=
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 <e53cb2f9d5882b0fbe82c589259bf043@lycos.com>
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 <20151221210811.GO4026@mtj.duckdns.org> <20151222035944.GG20661@kmo-pixel>
 <20151222052611.GA10487@xzibit.linux.bs1.fc.nec.co.jp>
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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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