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 3b1a5cdd631161e4ecd027cd8294ba2005ef4235..defcc964ecab656033b1a4f31018d737f719c446 100644 (file)
--- a/drivers/block/ublk_drv.c
+++ b/drivers/block/ublk_drv.c
@@ -2116,7 +2116,7 @@ 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)
@@ -2127,7 +2127,7 @@ 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;