3.2-stable review patch. If anyone has any objections, please let me know.
------------------
From: Bernd Schubert <bernd.schub...@itwm.fraunhofer.de>
commit f908ee9463b09ddd05e1c1a0111132212dc05fac upstream.
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.schub...@itwm.fraunhofer.de>
Signed-off-by: Jens Axboe <ax...@kernel.dk>
Signed-off-by: Ben Hutchings <b...@decadent.org.uk>
---
fs/bio.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/fs/bio.c b/fs/bio.c
index e453924..84da885 100644
--- a/fs/bio.c
+++ b/fs/bio.c
@@ -505,9 +505,14 @@ EXPORT_SYMBOL(bio_clone);
int bio_get_nr_vecs(struct block_device *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_sectors(q) / (PAGE_SIZE >> 9) + 1);
+
+ return min_t(unsigned, nr_pages, BIO_MAX_PAGES);
+
}
EXPORT_SYMBOL(bio_get_nr_vecs);
--
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