FAILED: patch "[PATCH] RDMA/mlx5: Fix a race for an ODP MR which leads to CQE with" failed to apply to 5.15-stable tree

The patch below does not apply to the 5.15-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x abb604a1a9c87255c7a6f3b784410a9707baf467
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2025021152-overdrive-premiere-cca5@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From abb604a1a9c87255c7a6f3b784410a9707baf467 Mon Sep 17 00:00:00 2001
From: Yishai Hadas <[email protected]>
Date: Sun, 19 Jan 2025 14:38:25 +0200
Subject: [PATCH] RDMA/mlx5: Fix a race for an ODP MR which leads to CQE with
error

This patch addresses a race condition for an ODP MR that can result in a CQE with an error on the UMR QP.

During the __mlx5_ib_dereg_mr() flow, the following sequence of calls occurs:

mlx5_revoke_mr()
mlx5r_umr_revoke_mr()
mlx5r_umr_post_send_wait()

At this point, the lkey is freed from the hardware's perspective.

However, concurrently, mlx5_ib_invalidate_range() might be triggered by another task attempting to invalidate a range for the same freed lkey.

This task will:
- Acquire the umem_odp->umem_mutex lock.
- Call mlx5r_umr_update_xlt() on the UMR QP.
- Since the lkey has already been freed, this can lead to a CQE error, causing the UMR QP to enter an error state [1].

To resolve this race condition, the umem_odp->umem_mutex lock is now also acquired as part of the mlx5_revoke_mr() scope. Upon successful revoke, we set umem_odp->private which points to that MR to NULL, preventing any further invalidation attempts on its lkey.

[1] From dmesg:

infiniband rocep8s0f0: dump_cqe:277:(pid 0): WC error: 6, Message: memory bind operation error
cqe_dump: 00000000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
cqe_dump: 00000010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
cqe_dump: 00000020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
cqe_dump: 00000030: 00 00 00 00 08 00 78 06 25 00 11 b9 00 0e dd d2

   WARNING: CPU: 15 PID: 1506 at drivers/infiniband/hw/mlx5/umr.c:394 mlx5r_umr_post_send_wait+0x15a/0x2b0 [mlx5_ib]
   Modules linked in: ip6table_mangle ip6table_natip6table_filter ip6_tables iptable_mangle xt_conntrack xt_MASQUERADE nf_conntrack_netlink nfnetlink xt_addrtype iptable_nat nf_nat br_netfilter rpcsec_gss_krb5 auth_rpcgss oid_registry overlay rpcrdma rdma_ucm ib_iser libiscsi scsi_transport_iscsi rdma_cm iw_cm ib_umad ib_ipoib ib_cm mlx5_ib ib_uverbs ib_core fuse mlx5_core
   CPU: 15 UID: 0 PID: 1506 Comm: ibv_rc_pingpong Not tainted 6.12.0-rc7+ #1626
   Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
   RIP: 0010:mlx5r_umr_post_send_wait+0x15a/0x2b0 [mlx5_ib]
   [..]
   Call Trace:
   <TASK>
   mlx5r_umr_update_xlt+0x23c/0x3e0 [mlx5_ib]
   mlx5_ib_invalidate_range+0x2e1/0x330 [mlx5_ib]
   __mmu_notifier_invalidate_range_start+0x1e1/0x240
   zap_page_range_single+0xf1/0x1a0
   madvise_vma_behavior+0x677/0x6e0
   do_madvise+0x1a2/0x4b0
   __x64_sys_madvise+0x25/0x30
   do_syscall_64+0x6b/0x140
   entry_SYSCALL_64_after_hwframe+0x76/0x7e

index 45d9dc9c6c8f..bb02b6adbf2c 100644
@@ -2021,6 +2021,11 @@ static int mlx5_revoke_mr(struct mlx5_ib_mr *mr)
 {
 	struct mlx5_ib_dev *dev = to_mdev(mr->ibmr.device);
 	struct mlx5_cache_ent *ent = mr->mmkey.cache_ent;
+	bool is_odp = is_odp_mr(mr);
+	int ret = 0;
+
+	if (is_odp)
+		mutex_lock(&to_ib_umem_odp(mr->umem)->umem_mutex);
 
 	if (mr->mmkey.cacheable && !mlx5r_umr_revoke_mr(mr) && !cache_ent_find_and_store(dev, mr)) {
 		ent = mr->mmkey.cache_ent;

@@ -2032,7 +2037,7 @@ static int mlx5_revoke_mr(struct mlx5_ib_mr *mr)
 			ent->tmp_cleanup_scheduled = true;
 		}
 		spin_unlock_irq(&ent->mkeys_queue.lock);
-		return 0;
+		goto out;
 	}
 
 	if (ent) {

@@ -2041,7 +2046,15 @@ static int mlx5_revoke_mr(struct mlx5_ib_mr *mr)
 		mr->mmkey.cache_ent = NULL;
 		spin_unlock_irq(&ent->mkeys_queue.lock);
 	}
-	return destroy_mkey(dev, mr);
+	ret = destroy_mkey(dev, mr);
+out:
+	if (is_odp) {
+		if (!ret)
+			to_ib_umem_odp(mr->umem)->private = NULL;
+		mutex_unlock(&to_ib_umem_odp(mr->umem)->umem_mutex);
+	}
+
+	return ret;
 }
 
 static int __mlx5_ib_dereg_mr(struct ib_mr *ibmr)

index f2eb940bddc8..f655859eec00 100644
@@ -268,6 +268,8 @@ static bool mlx5_ib_invalidate_range(struct mmu_interval_notifier *mni,
 	if (!umem_odp->npages)
 		goto out;
 	mr = umem_odp->private;
+	if (!mr)
+		goto out;
 
 	start = max_t(u64, ib_umem_start(umem_odp), range->start);
 	end = min_t(u64, ib_umem_end(umem_odp), range->end);