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Message-ID: <38a5ccc6-d0bc-41e0-99de-fe7902b1951f@linux.dev>
Date: Tue, 14 May 2024 10:53:05 +0200
From: Zhu Yanjun <zyjzyj2000@...il.com>
To: Håkon Bugge <haakon.bugge@...cle.com>,
linux-rdma@...r.kernel.org, linux-kernel@...r.kernel.org,
netdev@...r.kernel.org, rds-devel@....oracle.com
Cc: Jason Gunthorpe <jgg@...pe.ca>, Leon Romanovsky <leon@...nel.org>,
Saeed Mahameed <saeedm@...dia.com>, Tariq Toukan <tariqt@...dia.com>,
"David S . Miller" <davem@...emloft.net>, Eric Dumazet
<edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>, Tejun Heo <tj@...nel.org>,
Lai Jiangshan <jiangshanlai@...il.com>,
Allison Henderson <allison.henderson@...cle.com>,
Manjunath Patil <manjunath.b.patil@...cle.com>,
Mark Zhang <markzhang@...dia.com>, Chuck Lever <chuck.lever@...cle.com>,
Shiraz Saleem <shiraz.saleem@...el.com>, Yang Li <yang.lee@...ux.alibaba.com>
Subject: Re: [PATCH 0/6] rds: rdma: Add ability to force GFP_NOIO
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 ... ?
> 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
>
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