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bio allocation failure due to bio_get_nr_vecs()

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The number of bio_get_nr_vecs() is passed down via bio_alloc() to
bvec_alloc_bs(), which fails the bio allocation if
nr_iovecs > BIO_MAX_PAGES. For the underlying caller this causes an
unexpected bio allocation failure.
Limiting to queue_max_segments() is not sufficient, as max_segments
also might be very large.

bvec_alloc_bs(gfp_mask, nr_iovecs, ) => NULL when nr_iovecs  > BIO_MAX_PAGES
bio_alloc_bioset(gfp_mask, nr_iovecs, ...)
bio_alloc(GFP_NOIO, nvecs)
xfs_alloc_ioend_bio()

Signed-off-by: Bernd Schubert <bernd.schubert@itwm.fraunhofer.de>
Cc: stable@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Bernd Schubert 2012-05-11 16:36:44 +02:00 committed by Jens Axboe
parent 080399aaaf
commit f908ee9463
1 changed files with 6 additions and 1 deletions
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7
fs/bio.c
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@ -505,9 +505,14 @@ EXPORT_SYMBOL(bio_clone);
int bio_get_nr_vecs(struct block_device *bdev) int bio_get_nr_vecs(struct block_device *bdev)
{ {
struct request_queue *q = bdev_get_queue(bdev); struct request_queue *q = bdev_get_queue(bdev);
return min_t(unsigned, int nr_pages;
nr_pages = min_t(unsigned,
queue_max_segments(q), queue_max_segments(q),
queue_max_sectors(q) / (PAGE_SIZE >> 9) + 1); queue_max_sectors(q) / (PAGE_SIZE >> 9) + 1);
return min_t(unsigned, nr_pages, BIO_MAX_PAGES);
} }
EXPORT_SYMBOL(bio_get_nr_vecs); EXPORT_SYMBOL(bio_get_nr_vecs);