ublk: use vmalloc for ublk_device's __queues

[ Upstream commit c2f48453b7806d41f5a3270f206a5cd5640ed207 ]

struct ublk_device's __queues points to an allocation with up to
UBLK_MAX_NR_QUEUES (4096) queues, each of which have:
- struct ublk_queue (48 bytes)
- Tail array of up to UBLK_MAX_QUEUE_DEPTH (4096) struct ublk_io's,
  32 bytes each
This means the full allocation can exceed 512 MB, which may well be
impossible to service with contiguous physical pages. Switch to
kvcalloc() and kvfree(), since there is no need for physically
contiguous memory.

Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Fixes: 71f28f3136af ("ublk_drv: add io_uring based userspace block driver")
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20250620151008.3976463-2-csander@purestorage.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
index 9fd284fa76dcd71f97acef149275f643b26c70d9..8ded49f3b68b2603491cc4bae40b5cb2d2ee585b 100644 (file)
--- a/drivers/block/ublk_drv.c
+++ b/drivers/block/ublk_drv.c
@@ -2513,7 +2513,7 @@ static void ublk_deinit_queues(struct ublk_device *ub)
 
        for (i = 0; i < nr_queues; i++)
                ublk_deinit_queue(ub, i);
-       kfree(ub->__queues);
+       kvfree(ub->__queues);
 }
 
 static int ublk_init_queues(struct ublk_device *ub)
@@ -2524,7 +2524,7 @@ static int ublk_init_queues(struct ublk_device *ub)
        int i, ret = -ENOMEM;
 
        ub->queue_size = ubq_size;
-       ub->__queues = kcalloc(nr_queues, ubq_size, GFP_KERNEL);
+       ub->__queues = kvcalloc(nr_queues, ubq_size, GFP_KERNEL);
        if (!ub->__queues)
                return ret;