bio: use bio_kmalloc() in copy/map functions (a9e9dc24) · Commits · 戴 / test

Impact: remove possible deadlock condition There is no reason to use mempool backed allocation for map functions. Also, because kern mapping is used inside LLDs (e.g. for EH), using mempool backed allocation can lead to deadlock under extreme conditions (mempool already consumed by the time a request reached EH and requests are blocked on EH). Switch copy/map functions to bio_kmalloc(). Signed-off-by:

Tejun Heo <tj@kernel.org> Signed-off-by:

Jens Axboe <jens.axboe@oracle.com>

fs/bio.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -822,7 +822,7 @@ struct bio bio_copy_user_iov(struct request_queue q,
		return ERR_PTR(-ENOMEM);

		ret = -ENOMEM;
		bio = bio_alloc(gfp_mask, nr_pages);
		bio = bio_kmalloc(gfp_mask, nr_pages);
		if (!bio)
		goto out_bmd;

		@@ -946,7 +946,7 @@ static struct bio __bio_map_user_iov(struct request_queue q,
		if (!nr_pages)
		return ERR_PTR(-EINVAL);

		bio = bio_alloc(gfp_mask, nr_pages);
		bio = bio_kmalloc(gfp_mask, nr_pages);
		if (!bio)
		return ERR_PTR(-ENOMEM);

		@@ -1130,7 +1130,7 @@ static struct bio __bio_map_kern(struct request_queue q, void *data,
		int offset, i;
		struct bio *bio;

		bio = bio_alloc(gfp_mask, nr_pages);
		bio = bio_kmalloc(gfp_mask, nr_pages);
		if (!bio)
		return ERR_PTR(-ENOMEM);

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