A driver that has popped a handle from an FRMR pool can hit failures
that leave the handle in a state where it can't safely be returned
for reuse. The driver destroys the handle itself, but the pool has
no way to learn about it, so the in_use counter drifts upward.
Add ib_frmr_pool_drop to balance the pool's accounting in this case.
Every pop is now balanced by exactly one push or drop.
Fixes: 36680ef7bc ("RDMA/mlx5: Switch from MR cache to FRMR pools")
Link: https://patch.msgid.link/r/20260610000145.820592-9-michaelgur@nvidia.com
Signed-off-by: Michael Guralnik <michaelgur@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Failure to push a handle to the pool, caused by ENOMEM on queue page
allocation, will trigger missing in_use counter update, skewing pool
state indefinitely.
Fix that by moving the handling of handle destruction in such case
into the FRMR code, ensuring the handle is either pushed to the pool
or destroyed inside the same function.
Adjust mlx5_ib call site accordingly.
Fixes: ce5df0b891 ("IB/core: Introduce FRMR pools")
Link: https://patch.msgid.link/r/20260610000145.820592-8-michaelgur@nvidia.com
Signed-off-by: Michael Guralnik <michaelgur@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Add a configuration of pinned handles on a specific FRMR pool.
The configured amount of pinned handles will not be aged and will stay
available for users to claim.
Upon setting the amount of pinned handles to an FRMR pool, we will make
sure we have at least the pinned amount of handles associated with the
pool and create more, if necessary.
The count for pinned handles take into account handles that are used by
user MRs and handles in the queue.
Introduce a new FRMR operation of build_key that allows drivers to
manipulate FRMR keys supplied by the user, allowing failing for
unsupported properties and masking of properties that are modifiable.
Signed-off-by: Michael Guralnik <michaelgur@nvidia.com>
Reviewed-by: Yishai Hadas <yishaih@nvidia.com>
Signed-off-by: Edward Srouji <edwards@nvidia.com>
Link: https://patch.msgid.link/20260226-frmr_pools-v4-5-95360b54f15e@nvidia.com
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Add a generic Fast Registration Memory Region pools mechanism to allow
drivers to optimize memory registration performance.
Drivers that have the ability to reuse MRs or their underlying HW
objects can take advantage of the mechanism to keep a 'handle' for those
objects and use them upon user request.
We assume that to achieve this goal a driver and its HW should implement
a modify operation for the MRs that is able to at least clear and set the
MRs and in more advanced implementations also support changing a subset
of the MRs properties.
The mechanism is built using an RB-tree consisting of pools, each pool
represents a set of MR properties that are shared by all of the MRs
residing in the pool and are unmodifiable by the vendor driver or HW.
The exposed API from ib_core to the driver has 4 operations:
Init and cleanup - handles data structs and locks for the pools.
Push and pop - store and retrieve 'handle' for a memory registration
or deregistrations request.
The FRMR pools mechanism implements the logic to search the RB-tree for
a pool with matching properties and create a new one when needed and
requires the driver to implement creation and destruction of a 'handle'
when pool is empty or a handle is requested or is being destroyed.
Later patch will introduce Netlink API to interact with the FRMR pools
mechanism to allow users to both configure and track its usage.
A vendor wishing to configure FRMR pool without exposing it or without
exposing internal MR properties to users, should use the
kernel_vendor_key field in the pools key. This can be useful in a few
cases, e.g, when the FRMR handle has a vendor-specific un-modifiable
property that the user registering the memory might not be aware of.
Signed-off-by: Michael Guralnik <michaelgur@nvidia.com>
Reviewed-by: Yishai Hadas <yishaih@nvidia.com>
Signed-off-by: Edward Srouji <edwards@nvidia.com>
Link: https://patch.msgid.link/20260226-frmr_pools-v4-2-95360b54f15e@nvidia.com
Signed-off-by: Leon Romanovsky <leon@kernel.org>
