From: Satya Tangirala <satyat@google.com>
To: Eric Biggers <ebiggers@kernel.org>
Cc: linux-block@vger.kernel.org, Jens Axboe <axboe@kernel.dk>,
dm-devel@redhat.com, Miaohe Lin <linmiaohe@huawei.com>
Subject: Re: [PATCH v2 3/3] block: warn if !__GFP_DIRECT_RECLAIM in bio_crypt_set_ctx()
Date: Thu, 17 Sep 2020 22:26:06 +0000 [thread overview]
Message-ID: <20200917222606.GC421296@google.com> (raw)
In-Reply-To: <20200916035315.34046-4-ebiggers@kernel.org>
On Tue, Sep 15, 2020 at 08:53:15PM -0700, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@google.com>
>
> bio_crypt_set_ctx() assumes its gfp_mask argument always includes
> __GFP_DIRECT_RECLAIM, so that the mempool_alloc() will always succeed.
>
> For now this assumption is still fine, since no callers violate it.
> Making bio_crypt_set_ctx() able to fail would add unneeded complexity.
>
> However, if a caller didn't use __GFP_DIRECT_RECLAIM, it would be very
> hard to notice the bug. Make it easier by adding a WARN_ON_ONCE().
>
> Cc: Miaohe Lin <linmiaohe@huawei.com>
> Cc: Satya Tangirala <satyat@google.com>
> Signed-off-by: Eric Biggers <ebiggers@google.com>
> ---
> block/blk-crypto.c | 10 +++++++++-
> 1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/block/blk-crypto.c b/block/blk-crypto.c
> index bbe7974fd74f0..5da43f0973b46 100644
> --- a/block/blk-crypto.c
> +++ b/block/blk-crypto.c
> @@ -81,7 +81,15 @@ subsys_initcall(bio_crypt_ctx_init);
> void bio_crypt_set_ctx(struct bio *bio, const struct blk_crypto_key *key,
> const u64 dun[BLK_CRYPTO_DUN_ARRAY_SIZE], gfp_t gfp_mask)
> {
> - struct bio_crypt_ctx *bc = mempool_alloc(bio_crypt_ctx_pool, gfp_mask);
> + struct bio_crypt_ctx *bc;
> +
> + /*
> + * The caller must use a gfp_mask that contains __GFP_DIRECT_RECLAIM so
> + * that the mempool_alloc() can't fail.
> + */
> + WARN_ON_ONCE(!(gfp_mask & __GFP_DIRECT_RECLAIM));
> +
> + bc = mempool_alloc(bio_crypt_ctx_pool, gfp_mask);
>
> bc->bc_key = key;
> memcpy(bc->bc_dun, dun, sizeof(bc->bc_dun));
> --
Looks good!
Reviewed-by: Satya Tangirala <satyat@google.com>
> 2.28.0
>
next prev parent reply other threads:[~2020-09-17 22:26 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-16 3:53 [PATCH v2 0/3] block: fix up bio_crypt_ctx allocation Eric Biggers
2020-09-16 3:53 ` [PATCH v2 1/3] block: make bio_crypt_clone() able to fail Eric Biggers
2020-09-17 22:17 ` Satya Tangirala
2020-09-24 0:56 ` Mike Snitzer
2020-09-16 3:53 ` [PATCH v2 2/3] block: make blk_crypto_rq_bio_prep() " Eric Biggers
2020-09-17 22:19 ` Satya Tangirala
2020-09-24 0:57 ` Mike Snitzer
2020-09-16 3:53 ` [PATCH v2 3/3] block: warn if !__GFP_DIRECT_RECLAIM in bio_crypt_set_ctx() Eric Biggers
2020-09-17 22:26 ` Satya Tangirala [this message]
2020-09-28 20:59 ` [PATCH v2 0/3] block: fix up bio_crypt_ctx allocation Eric Biggers
2020-10-05 16:42 ` Eric Biggers
2020-10-05 16:48 ` Jens Axboe
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