RDMA/mlx5: Fix corruption of reg_pages in mlx5_ib_rereg_user_mr()

BugLink: https://bugs.launchpad.net/bugs/1910111
[ Upstream commit fc3325701a6353594083f08e297d4c1965c601aa ]

reg_pages should always contain mr->npage since when the mr is finally
de-reg'd it is always subtracted out.

If there were any error exits then mlx5_ib_rereg_user_mr() would leave the
reg_pages adjusted and this will cause it to be double subtracted
eventually.

The manipulation of reg_pages is inherently connected to the umem, so lift
it out of set_mr_fields() and only adjust it around creating/destroying a
umem.

reg_pages is only used for diagnostics in sysfs.

Fixes: 7d0cc6edcc70 ("IB/mlx5: Add MR cache for large UMR regions")
Link: https://lore.kernel.org/r/20201026131936.1335664-3-leon@kernel.org
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Paolo Pisati <paolo.pisati@canonical.com>

diff --git a/drivers/infiniband/hw/mlx5/mr.c b/drivers/infiniband/hw/mlx5/mr.c
index b261797b258fd7f9425d44c43c5ec8f68ab15d9b..3468ae804eaee10df6a21b854a9af1023d7bc245 100644 (file)
--- a/drivers/infiniband/hw/mlx5/mr.c
+++ b/drivers/infiniband/hw/mlx5/mr.c
@@ -1247,10 +1247,8 @@ err_1:
 }
 
 static void set_mr_fields(struct mlx5_ib_dev *dev, struct mlx5_ib_mr *mr,
-                         int npages, u64 length, int access_flags)
+                         u64 length, int access_flags)
 {
-       mr->npages = npages;
-       atomic_add(npages, &dev->mdev->priv.reg_pages);
        mr->ibmr.lkey = mr->mmkey.key;
        mr->ibmr.rkey = mr->mmkey.key;
        mr->ibmr.length = length;
@@ -1290,8 +1288,7 @@ static struct ib_mr *mlx5_ib_get_dm_mr(struct ib_pd *pd, u64 start_addr,
 
        kfree(in);
 
-       mr->umem = NULL;
-       set_mr_fields(dev, mr, 0, length, acc);
+       set_mr_fields(dev, mr, length, acc);
 
        return &mr->ibmr;
 
@@ -1419,7 +1416,9 @@ struct ib_mr *mlx5_ib_reg_user_mr(struct ib_pd *pd, u64 start, u64 length,
        mlx5_ib_dbg(dev, "mkey 0x%x\n", mr->mmkey.key);
 
        mr->umem = umem;
-       set_mr_fields(dev, mr, npages, length, access_flags);
+       mr->npages = npages;
+       atomic_add(mr->npages, &dev->mdev->priv.reg_pages);
+       set_mr_fields(dev, mr, length, access_flags);
 
        if (xlt_with_umr && !(access_flags & IB_ACCESS_ON_DEMAND)) {
                /*
@@ -1531,8 +1530,6 @@ int mlx5_ib_rereg_user_mr(struct ib_mr *ib_mr, int flags, u64 start,
        mlx5_ib_dbg(dev, "start 0x%llx, virt_addr 0x%llx, length 0x%llx, access_flags 0x%x\n",
                    start, virt_addr, length, access_flags);
 
-       atomic_sub(mr->npages, &dev->mdev->priv.reg_pages);
-
        if (!mr->umem)
                return -EINVAL;
 
@@ -1553,12 +1550,17 @@ int mlx5_ib_rereg_user_mr(struct ib_mr *ib_mr, int flags, u64 start,
                 * used.
                 */
                flags |= IB_MR_REREG_TRANS;
+               atomic_sub(mr->npages, &dev->mdev->priv.reg_pages);
+               mr->npages = 0;
                ib_umem_release(mr->umem);
                mr->umem = NULL;
+
                err = mr_umem_get(dev, addr, len, access_flags, &mr->umem,
                                  &npages, &page_shift, &ncont, &order);
                if (err)
                        goto err;
+               mr->npages = ncont;
+               atomic_add(mr->npages, &dev->mdev->priv.reg_pages);
        }
 
        if (!mlx5_ib_can_reconfig_with_umr(dev, mr->access_flags,
@@ -1609,7 +1611,7 @@ int mlx5_ib_rereg_user_mr(struct ib_mr *ib_mr, int flags, u64 start,
                        goto err;
        }
 
-       set_mr_fields(dev, mr, npages, len, access_flags);
+       set_mr_fields(dev, mr, len, access_flags);
 
        return 0;