Re: [PATCH 0/6] rds: rdma: Add ability to force GFP_NOIO

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On 14.05.24 10:53, Zhu Yanjun wrote:
On 13.05.24 14:53, Håkon Bugge wrote:
This series enables RDS and the RDMA stack to be used as a block I/O
device. This to support a filesystem on top of a raw block device

This is to support a filesystem ... ?

Sorry. my bad. I mean, normally rds is used to act as a communication protocol between Oracle databases. Now in this patch series, it seems that rds acts as a communication protocol to support a filesystem. So I am curious which filesystem that rds is supporting?

Thanks a lot.
Zhu Yanjun


which uses RDS and the RDMA stack as the network transport layer.

Under intense memory pressure, we get memory reclaims. Assume the
filesystem reclaims memory, goes to the raw block device, which calls
into RDS, which calls the RDMA stack. Now, if regular GFP_KERNEL
allocations in RDS or the RDMA stack require reclaims to be fulfilled,
we end up in a circular dependency.

We break this circular dependency by:

1. Force all allocations in RDS and the relevant RDMA stack to use
    GFP_NOIO, by means of a parenthetic use of
    memalloc_noio_{save,restore} on all relevant entry points.

2. Make sure work-queues inherits current->flags
    wrt. PF_MEMALLOC_{NOIO,NOFS}, such that work executed on the
    work-queue inherits the same flag(s).

Håkon Bugge (6):
   workqueue: Inherit NOIO and NOFS alloc flags
   rds: Brute force GFP_NOIO
   RDMA/cma: Brute force GFP_NOIO
   RDMA/cm: Brute force GFP_NOIO
   RDMA/mlx5: Brute force GFP_NOIO
   net/mlx5: Brute force GFP_NOIO

  drivers/infiniband/core/cm.c                  | 15 ++++-
  drivers/infiniband/core/cma.c                 | 20 ++++++-
  drivers/infiniband/hw/mlx5/main.c             | 22 +++++--
  .../net/ethernet/mellanox/mlx5/core/main.c    | 14 ++++-
  include/linux/workqueue.h                     |  2 +
  kernel/workqueue.c                            | 17 ++++++
  net/rds/af_rds.c                              | 60 ++++++++++++++++++-
  7 files changed, 138 insertions(+), 12 deletions(-)

--
2.39.3



--
Best




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