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    SubjectRE: WARNING in dma_map_page_attrs
    Date

    > From: hch@lst.de <hch@lst.de>
    > Sent: Tuesday, October 27, 2020 1:41 PM
    >
    > On Mon, Oct 26, 2020 at 05:23:48AM +0000, Parav Pandit wrote:
    > > Hi Christoph,
    > >
    > > > From: Jakub Kicinski <kuba@kernel.org>
    > > > Sent: Saturday, October 24, 2020 11:45 PM
    > > >
    > > > CC: rdma, looks like rdma from the stack trace
    > > >
    > > > On Fri, 23 Oct 2020 20:07:17 -0700 syzbot wrote:
    > > > > syzbot has found a reproducer for the following issue on:
    > > > >
    > > > > HEAD commit: 3cb12d27 Merge tag 'net-5.10-rc1' of
    > git://git.kernel.org/..
    > >
    > > In [1] you mentioned that dma_mask should not be set for dma_virt_ops.
    > > So patch [2] removed it.
    > >
    > > But check to validate the dma mask for all dma_ops was added in [3].
    > >
    > > What is the right way? Did I misunderstood your comment about
    > dma_mask in [1]?
    >
    > No, I did not say we don't need the mask. I said copying over the various
    > dma-related fields from the parent is bogus.
    >
    > I think rxe (and ther other drivers/infiniband/sw drivers) need a simple
    > dma_coerce_mask_and_coherent and nothing else.

    I see. Does below fix make sense?
    Is DMA_MASK_NONE correct?

    From cfad78c35788b4ff604abedd96559500c5fd2a72 Mon Sep 17 00:00:00 2001
    From: Parav Pandit <parav@nvidia.com>
    Date: Tue, 27 Oct 2020 14:20:07 +0200
    Subject: [PATCH] RDMA: Fix software RDMA drivers for dma mapping error

    A cited commit in fixes tag avoided setting dma_mask of the ib_device.
    Commit [1] made dma_mask as mandetory field to be setup even for
    dma_virt_ops based dma devices.

    Fix it by setting empty DMA MASK for software based RDMA devices.

    [1] commit: f959dcd6ddfd2 ("dma-direct: Fix potential NULL pointer dereference")

    Reported-by: syzbot+34dc2fea3478e659af01@syzkaller.appspotmail.com
    Fixes: e0477b34d9d1 ("RDMA: Explicitly pass in the dma_device to ib_register_device")
    Signed-off-by: Parav Pandit <parav@nvidia.com>
    ---
    drivers/infiniband/sw/rdmavt/vt.c | 5 +++--
    drivers/infiniband/sw/rxe/rxe_verbs.c | 4 +++-
    drivers/infiniband/sw/siw/siw_main.c | 5 +++--
    3 files changed, 9 insertions(+), 5 deletions(-)

    diff --git a/drivers/infiniband/sw/rdmavt/vt.c b/drivers/infiniband/sw/rdmavt/vt.c
    index 52218684ad4a..1b456f4d4fcf 100644
    --- a/drivers/infiniband/sw/rdmavt/vt.c
    +++ b/drivers/infiniband/sw/rdmavt/vt.c
    @@ -580,8 +580,9 @@ int rvt_register_device(struct rvt_dev_info *rdi)

    /* DMA Operations */
    rdi->ibdev.dev.dma_parms = rdi->ibdev.dev.parent->dma_parms;
    - dma_set_coherent_mask(&rdi->ibdev.dev,
    - rdi->ibdev.dev.parent->coherent_dma_mask);
    + ret = dma_coerce_mask_and_coherent(&rdi->ibdev.dev, DMA_MASK_NONE);
    + if (ret)
    + goto bail_wss;

    /* Protection Domain */
    spin_lock_init(&rdi->n_pds_lock);
    diff --git a/drivers/infiniband/sw/rxe/rxe_verbs.c b/drivers/infiniband/sw/rxe/rxe_verbs.c
    index 1fc022362fbe..357787688293 100644
    --- a/drivers/infiniband/sw/rxe/rxe_verbs.c
    +++ b/drivers/infiniband/sw/rxe/rxe_verbs.c
    @@ -1130,7 +1130,9 @@ int rxe_register_device(struct rxe_dev *rxe, const char *ibdev_name)
    rxe->ndev->dev_addr);
    dev->dev.dma_parms = &rxe->dma_parms;
    dma_set_max_seg_size(&dev->dev, UINT_MAX);
    - dma_set_coherent_mask(&dev->dev, dma_get_required_mask(&dev->dev));
    + err = dma_coerce_mask_and_coherent(&dev->dev, DMA_MASK_NONE);
    + if (err)
    + return err;

    dev->uverbs_cmd_mask = BIT_ULL(IB_USER_VERBS_CMD_GET_CONTEXT)
    | BIT_ULL(IB_USER_VERBS_CMD_CREATE_COMP_CHANNEL)
    diff --git a/drivers/infiniband/sw/siw/siw_main.c b/drivers/infiniband/sw/siw/siw_main.c
    index ca8bc7296867..d3dc50a42dab 100644
    --- a/drivers/infiniband/sw/siw/siw_main.c
    +++ b/drivers/infiniband/sw/siw/siw_main.c
    @@ -384,8 +384,9 @@ static struct siw_device *siw_device_create(struct net_device *netdev)
    base_dev->dev.parent = parent;
    base_dev->dev.dma_parms = &sdev->dma_parms;
    dma_set_max_seg_size(&base_dev->dev, UINT_MAX);
    - dma_set_coherent_mask(&base_dev->dev,
    - dma_get_required_mask(&base_dev->dev));
    + if (dma_coerce_mask_and_coherent(&base_dev->dev, DMA_MASK_NONE))
    + goto error;
    +
    base_dev->num_comp_vectors = num_possible_cpus();

    xa_init_flags(&sdev->qp_xa, XA_FLAGS_ALLOC1);
    --
    2.26.2
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