Messages in this thread | | | Date | Wed, 28 May 2014 23:16:17 +0800 | From | Jet Chen <> | Subject | Re: [: [bio] kernel BUG at drivers/block/virtio_blk.c:166!] |
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On 05/27/2014 07:24 PM, Maurizio Lombardi wrote: > On Tue, May 27, 2014 at 10:43:59AM +0200, Maurizio Lombardi wrote: >> >> But now I'm suspicious of this part of commit 3979ef4dcf: >> >> failed: >> bvec->bv_page = NULL; >> bvec->bv_len = 0; >> bvec->bv_offset = 0; >> bio->bi_vcnt--; <---------------- >> blk_recount_segments(q, bio); >> return 0; >> >> Is decreasing bi_vcnt sufficient to guarantee that blk_recount_segments() >> recalculates the correct number of physical segments? >> Looking at the __blk_recalc_rq_segments() it appears it may not be the case. >> >> The question is how can we restore the correct number of physical segments in case >> of failure without breaking anything... >> > > If my hypothesis is correct, the following patch should trigger a kernel panic, > Jet Chen, can you try it and let me know whether the BUG_ON is hit or not?
Sorry for late respond. Dongsu has sent a patch for this issue. message-id <1401289778-9840-1-git-send-email-dongsu.park@profitbricks.com> Do you still need me to test the following patch ?
> > diff --git a/block/bio.c b/block/bio.c > index 0443694..763868f 100644 > --- a/block/bio.c > +++ b/block/bio.c > @@ -701,6 +701,7 @@ static int __bio_add_page(struct request_queue *q, struct bio *bio, struct page > unsigned int max_sectors) > { > int retried_segments = 0; > + unsigned int phys_segments_orig; > struct bio_vec *bvec; > > /* > @@ -751,6 +752,9 @@ static int __bio_add_page(struct request_queue *q, struct bio *bio, struct page > if (bio->bi_vcnt >= bio->bi_max_vecs) > return 0; > > + blk_recount_segments(q, bio); > + phys_segments_orig = bio->bi_phys_segments; > + > /* > * setup the new entry, we might clear it again later if we > * cannot add the page > @@ -811,6 +815,7 @@ static int __bio_add_page(struct request_queue *q, struct bio *bio, struct page > bvec->bv_offset = 0; > bio->bi_vcnt--; > blk_recount_segments(q, bio); > + BUG_ON(phys_segments_orig != bio->bi_phys_segments); > return 0; > } > > > Regards, > Maurizio Lombardi >
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