bio allocation failure due to bio_get_nr_vecs()
authorBernd Schubert <bernd.schubert@itwm.fraunhofer.de>
Fri, 11 May 2012 14:36:44 +0000 (16:36 +0200)
committerBen Hutchings <ben@decadent.org.uk>
Wed, 30 May 2012 23:43:15 +0000 (00:43 +0100)
commit6609c1cd5ca261eadaddaca83d71977a8dfb4032
tree7c3d0245aaedd443251ccf5973705e678ca49943
parentc8616ea3986b2e65f77a5442ca056683d6df987d
bio allocation failure due to bio_get_nr_vecs()

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.schubert@itwm.fraunhofer.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
fs/bio.c