wireguard-linux/net/rds/ib_rdma.c, branch devel

net/rds: Optimize rds_ib_laddr_check

2026-04-12T20:33:19Z

rds_ib_laddr_check() creates a CM_ID and attempts to bind the address in question to it. This in order to qualify the allegedly local address as a usable IB/RoCE address. In the field, ExaWatcher runs rds-ping to all ports in the fabric from all local ports. This using all active ToS'es. In a full rack system, we have 14 cell servers and eight db servers. Typically, 6 ToS'es are used. This implies 528 rds-ping invocations per ExaWatcher's "RDSinfo" interval. Adding to this, each rds-ping invocation creates eight sockets and binds the local address to them: socket(AF_RDS, SOCK_SEQPACKET, 0) = 3 bind(3, {sa_family=AF_INET, sin_port=htons(0), sin_addr=inet_addr("192.168.36.2")}, 16) = 0 socket(AF_RDS, SOCK_SEQPACKET, 0) = 4 bind(4, {sa_family=AF_INET, sin_port=htons(0), sin_addr=inet_addr("192.168.36.2")}, 16) = 0 socket(AF_RDS, SOCK_SEQPACKET, 0) = 5 bind(5, {sa_family=AF_INET, sin_port=htons(0), sin_addr=inet_addr("192.168.36.2")}, 16) = 0 socket(AF_RDS, SOCK_SEQPACKET, 0) = 6 bind(6, {sa_family=AF_INET, sin_port=htons(0), sin_addr=inet_addr("192.168.36.2")}, 16) = 0 socket(AF_RDS, SOCK_SEQPACKET, 0) = 7 bind(7, {sa_family=AF_INET, sin_port=htons(0), sin_addr=inet_addr("192.168.36.2")}, 16) = 0 socket(AF_RDS, SOCK_SEQPACKET, 0) = 8 bind(8, {sa_family=AF_INET, sin_port=htons(0), sin_addr=inet_addr("192.168.36.2")}, 16) = 0 socket(AF_RDS, SOCK_SEQPACKET, 0) = 9 bind(9, {sa_family=AF_INET, sin_port=htons(0), sin_addr=inet_addr("192.168.36.2")}, 16) = 0 socket(AF_RDS, SOCK_SEQPACKET, 0) = 10 bind(10, {sa_family=AF_INET, sin_port=htons(0), sin_addr=inet_addr("192.168.36.2")}, 16) = 0 So, at every interval ExaWatcher executes rds-ping's, 4224 CM_IDs are allocated, considering this full-rack system. After the a CM_ID has been allocated, rdma_bind_addr() is called, with the port number being zero. This implies that the CMA will attempt to search for an un-used ephemeral port. Simplified, the algorithm is to start at a random position in the available port space, and then if needed, iterate until an un-used port is found. The book-keeping of used ports uses the idr system, which again uses slab to allocate new struct idr_layer's. The size is 2092 bytes and slab tries to reduce the wasted space. Hence, it chooses an order:3 allocation, for which 15 idr_layer structs will fit and only 1388 bytes are wasted per the 32KiB order:3 chunk. Although this order:3 allocation seems like a good space/speed trade-off, it does not resonate well with how it used by the CMA. The combination of the randomized starting point in the port space (which has close to zero spatial locality) and the close proximity in time of the 4224 invocations of the rds-ping's, creates a memory hog for order:3 allocations. These costly allocations may need reclaims and/or compaction. At worst, they may fail and produce a stack trace such as (from uek4): [] __inc_zone_page_state+0x35/0x40 [] page_add_file_rmap+0x57/0x60 [] remove_migration_pte+0x3f/0x3c0 [ksplice_6cn872bt_vmlinux_new] [] rmap_walk+0xd8/0x340 [] remove_migration_ptes+0x40/0x50 [] migrate_pages+0x3ec/0x890 [] compact_zone+0x32d/0x9a0 [] compact_zone_order+0x6d/0x90 [] try_to_compact_pages+0x102/0x270 [] __alloc_pages_direct_compact+0x46/0x100 [] __alloc_pages_nodemask+0x74b/0xaa0 [] alloc_pages_current+0x91/0x110 [] new_slab+0x38b/0x480 [] __slab_alloc+0x3b7/0x4a0 [ksplice_s0dk66a8_vmlinux_new] [] kmem_cache_alloc+0x1fb/0x250 [] idr_layer_alloc+0x36/0x90 [] idr_get_empty_slot+0x28c/0x3d0 [] idr_alloc+0x4d/0xf0 [] cma_alloc_port+0x4d/0xa0 [rdma_cm] [] rdma_bind_addr+0x2ae/0x5b0 [rdma_cm] [] rds_ib_laddr_check+0x83/0x2c0 [ksplice_6l2xst5i_rds_rdma_new] [] rds_trans_get_preferred+0x5b/0xa0 [rds] [] rds_bind+0x212/0x280 [rds] [] SYSC_bind+0xe6/0x120 [] SyS_bind+0xe/0x10 [] system_call_fastpath+0x18/0xd4 To avoid these excessive calls to rdma_bind_addr(), we optimize rds_ib_laddr_check() by simply checking if the address in question has been used before. The rds_rdma module keeps track of addresses associated with IB devices, and the function rds_ib_get_device() is used to determine if the address already has been qualified as a valid local address. If not found, we call the legacy rds_ib_laddr_check(), now renamed to rds_ib_laddr_check_cm(). Signed-off-by: Håkon Bugge Signed-off-by: Somasundaram Krishnasamy Signed-off-by: Gerd Rausch Signed-off-by: Allison Henderson Link: https://patch.msgid.link/20260408080420.540032-2-achender@kernel.org Signed-off-by: Jakub Kicinski

rds: ib: reject FRMR registration before IB connection is established

2026-04-02T00:52:40Z

rds_ib_get_mr() extracts the rds_ib_connection from conn->c_transport_data and passes it to rds_ib_reg_frmr() for FRWR memory registration. On a fresh outgoing connection, ic is allocated in rds_ib_conn_alloc() with i_cm_id = NULL because the connection worker has not yet called rds_ib_conn_path_connect() to create the rdma_cm_id. When sendmsg() with RDS_CMSG_RDMA_MAP is called on such a connection, the sendmsg path parses the control message before any connection establishment, allowing rds_ib_post_reg_frmr() to dereference ic->i_cm_id->qp and crash the kernel. The existing guard in rds_ib_reg_frmr() only checks for !ic (added in commit 9e630bcb7701), which does not catch this case since ic is allocated early and is always non-NULL once the connection object exists. KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017] RIP: 0010:rds_ib_post_reg_frmr+0x50e/0x920 Call Trace: rds_ib_post_reg_frmr (net/rds/ib_frmr.c:167) rds_ib_map_frmr (net/rds/ib_frmr.c:252) rds_ib_reg_frmr (net/rds/ib_frmr.c:430) rds_ib_get_mr (net/rds/ib_rdma.c:615) __rds_rdma_map (net/rds/rdma.c:295) rds_cmsg_rdma_map (net/rds/rdma.c:860) rds_sendmsg (net/rds/send.c:1363) ____sys_sendmsg do_syscall_64 Add a check in rds_ib_get_mr() that verifies ic, i_cm_id, and qp are all non-NULL before proceeding with FRMR registration, mirroring the guard already present in rds_ib_post_inv(). Return -ENODEV when the connection is not ready, which the existing error handling in rds_cmsg_send() converts to -EAGAIN for userspace retry and triggers rds_conn_connect_if_down() to start the connection worker. Fixes: 1659185fb4d0 ("RDS: IB: Support Fastreg MR (FRMR) memory registration mode") Reported-by: Xiang Mei Signed-off-by: Weiming Shi Reviewed-by: Allison Henderson Link: https://patch.msgid.link/20260330163237.2752440-2-bestswngs@gmail.com Signed-off-by: Jakub Kicinski

Convert 'alloc_obj' family to use the new default GFP_KERNEL argument

2026-02-22T01:09:51Z

This was done entirely with mindless brute force, using git grep -l '\

treewide: Replace kmalloc with kmalloc_obj for non-scalar types

2026-02-21T09:02:28Z

This is the result of running the Coccinelle script from scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to avoid scalar types (which need careful case-by-case checking), and instead replace kmalloc-family calls that allocate struct or union object instances: Single allocations: kmalloc(sizeof(TYPE), ...) are replaced with: kmalloc_obj(TYPE, ...) Array allocations: kmalloc_array(COUNT, sizeof(TYPE), ...) are replaced with: kmalloc_objs(TYPE, COUNT, ...) Flex array allocations: kmalloc(struct_size(PTR, FAM, COUNT), ...) are replaced with: kmalloc_flex(*PTR, FAM, COUNT, ...) (where TYPE may also be *VAR) The resulting allocations no longer return "void *", instead returning "TYPE *". Signed-off-by: Kees Cook

net: WQ_PERCPU added to alloc_workqueue users

2025-09-23T00:40:30Z

Currently if a user enqueue a work item using schedule_delayed_work() the used wq is "system_wq" (per-cpu wq) while queue_delayed_work() use WORK_CPU_UNBOUND (used when a cpu is not specified). The same applies to schedule_work() that is using system_wq and queue_work(), that makes use again of WORK_CPU_UNBOUND. This lack of consistentcy cannot be addressed without refactoring the API. alloc_workqueue() treats all queues as per-CPU by default, while unbound workqueues must opt-in via WQ_UNBOUND. This default is suboptimal: most workloads benefit from unbound queues, allowing the scheduler to place worker threads where they’re needed and reducing noise when CPUs are isolated. This change adds a new WQ_PERCPU flag at the network subsystem, to explicitly request the use of the per-CPU behavior. Both flags coexist for one release cycle to allow callers to transition their calls. Once migration is complete, WQ_UNBOUND can be removed and unbound will become the implicit default. With the introduction of the WQ_PERCPU flag (equivalent to !WQ_UNBOUND), any alloc_workqueue() caller that doesn’t explicitly specify WQ_UNBOUND must now use WQ_PERCPU. All existing users have been updated accordingly. Suggested-by: Tejun Heo Signed-off-by: Marco Crivellari Link: https://patch.msgid.link/20250918142427.309519-4-marco.crivellari@suse.com Signed-off-by: Jakub Kicinski

net/rds: remove unused struct 'rds_ib_dereg_odp_mr'

2024-10-03T23:42:52Z

'rds_ib_dereg_odp_mr' has been unused since the original commit 2eafa1746f17 ("net/rds: Handle ODP mr registration/unregistration"). Remove it. Signed-off-by: Dr. David Alan Gilbert Reviewed-by: Simon Horman Reviewed-by: Allison Henderson Reviewed-by: Zhu Yanjun Link: https://patch.msgid.link/20240930134358.48647-1-linux@treblig.org Signed-off-by: Jakub Kicinski

RDMA/rds: Remove FMR support for memory registration

2020-06-02T23:32:53Z

Use FRWR method for memory registration by default and remove the ancient and unsafe FMR method. Link: https://lore.kernel.org/r/3-v3-f58e6669d5d3+2cf-fmr_removal_jgg@mellanox.com Signed-off-by: Max Gurtovoy Signed-off-by: Jason Gunthorpe

net/rds: Use prefetch for On-Demand-Paging MR

2020-01-18T09:48:19Z

Try prefetching pages when using On-Demand-Paging MR using ib_advise_mr. Signed-off-by: Hans Westgaard Ry Acked-by: Santosh Shilimkar Signed-off-by: Leon Romanovsky

net/rds: Handle ODP mr registration/unregistration

2020-01-18T09:48:19Z

On-Demand-Paging MRs are registered using ib_reg_user_mr and unregistered with ib_dereg_mr. Signed-off-by: Hans Westgaard Ry Acked-by: Santosh Shilimkar Signed-off-by: Leon Romanovsky

net/rds: Fix NULL/ERR_PTR inconsistency

2019-07-17T19:06:52Z

Make function "rds_ib_try_reuse_ibmr" return NULL in case memory region could not be allocated, since callers simply check if the return value is not NULL. Signed-off-by: Gerd Rausch Acked-by: Santosh Shilimkar Signed-off-by: David S. Miller