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SubjectRe: [RFC PATCH] bio integrity: do not assume bio_integrity_pool exists if bioset exists


On Wed, 1 Jul 2015, Mike Snitzer wrote:

> bio_integrity_alloc() and bio_integrity_free() assume that if a bio was
> allocated from a bioset that that bioset also had its bio_integrity_pool
> allocated using bioset_integrity_create(). This is a very bad
> assumption given that bioset_create() and bioset_integrity_create() are
> completely disjoint. Not all callers of bioset_create() have been
> trained to also call bioset_integrity_create() -- and they may not care
> to be.
>
> Fix this by falling back to kmalloc'ing 'struct bio_integrity_payload'
> rather than force all bioset consumers to (wastefully) preallocate a
> bio_integrity_pool that they very likely won't actually need (given the
> niche nature of the current block integrity support).
>
> Otherwise, a NULL pointer "Kernel BUG" with a trace like the following
> will be observed (as seen on s390x using zfcp storage) because dm-io
> doesn't use bioset_integrity_create() when creating its bioset:
>
> [ 791.643338] Call Trace:
> [ 791.643339] ([<00000003df98b848>] 0x3df98b848)
> [ 791.643341] [<00000000002c5de8>] bio_integrity_alloc+0x48/0xf8
> [ 791.643348] [<00000000002c6486>] bio_integrity_prep+0xae/0x2f0
> [ 791.643349] [<0000000000371e38>] blk_queue_bio+0x1c8/0x3d8
> [ 791.643355] [<000000000036f8d0>] generic_make_request+0xc0/0x100
> [ 791.643357] [<000000000036f9b2>] submit_bio+0xa2/0x198
> [ 791.643406] [<000003ff801f9774>] dispatch_io+0x15c/0x3b0 [dm_mod]
> [ 791.643419] [<000003ff801f9b3e>] dm_io+0x176/0x2f0 [dm_mod]
> [ 791.643423] [<000003ff8074b28a>] do_reads+0x13a/0x1a8 [dm_mirror]
> [ 791.643425] [<000003ff8074b43a>] do_mirror+0x142/0x298 [dm_mirror]
> [ 791.643428] [<0000000000154fca>] process_one_work+0x18a/0x3f8
> [ 791.643432] [<000000000015598a>] worker_thread+0x132/0x3b0
> [ 791.643435] [<000000000015d49a>] kthread+0xd2/0xd8
> [ 791.643438] [<00000000005bc0ca>] kernel_thread_starter+0x6/0xc
> [ 791.643446] [<00000000005bc0c4>] kernel_thread_starter+0x0/0xc
>
> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
> Cc: stable@vger.kernel.org

Acked-by: Mikulas Patocka <mpatocka@redhat.com>

> ---
> block/bio-integrity.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> NOTE: this serves as a more generic fix in the block layer rather than
> the dm-io specific fix which isn't ideal (due to potential for memory
> waste), see:
> https://git.kernel.org/cgit/linux/kernel/git/device-mapper/linux-dm.git/commit/?h=for-next&id=17dbe96d4f8a6f87004e6cfb5944872dfe2edb9f
>
> diff --git a/block/bio-integrity.c b/block/bio-integrity.c
> index 0436c21..719b715 100644
> --- a/block/bio-integrity.c
> +++ b/block/bio-integrity.c
> @@ -51,7 +51,7 @@ struct bio_integrity_payload *bio_integrity_alloc(struct bio *bio,
> unsigned long idx = BIO_POOL_NONE;
> unsigned inline_vecs;
>
> - if (!bs) {
> + if (!bs || !bs->bio_integrity_pool) {
> bip = kmalloc(sizeof(struct bio_integrity_payload) +
> sizeof(struct bio_vec) * nr_vecs, gfp_mask);
> inline_vecs = nr_vecs;
> @@ -104,7 +104,7 @@ void bio_integrity_free(struct bio *bio)
> kfree(page_address(bip->bip_vec->bv_page) +
> bip->bip_vec->bv_offset);
>
> - if (bs) {
> + if (bs && bs->bio_integrity_pool) {
> if (bip->bip_slab != BIO_POOL_NONE)
> bvec_free(bs->bvec_integrity_pool, bip->bip_vec,
> bip->bip_slab);
> --
> 2.3.2 (Apple Git-55)
>
>


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