netdev - Re: [PATCH net] ionic: Fix allocation of q/cq info structures from device local node

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Message-ID: <20230411124945.527b0ee4@kernel.org>
Date:   Tue, 11 Apr 2023 12:49:45 -0700
From:   Jakub Kicinski <kuba@...nel.org>
To:     Leon Romanovsky <leon@...nel.org>
Cc:     Brett Creeley <bcreeley@....com>,
        Brett Creeley <brett.creeley@....com>, davem@...emloft.net,
        netdev@...r.kernel.org, drivers@...sando.io,
        shannon.nelson@....com, neel.patel@....com
Subject: Re: [PATCH net] ionic: Fix allocation of q/cq info structures from
 device local node

On Tue, 11 Apr 2023 15:47:04 +0300 Leon Romanovsky wrote:
> > We want to allocate memory from the node local to our PCI device, which is
> > not necessarily the same as the node that the thread is running on where
> > vzalloc() first tries to alloc.  
> 
> I'm not sure about it as you are running kernel thread which is
> triggered directly by device and most likely will run on same node as
> PCI device.

Isn't that true only for bus-side probing?
If you bind/unbind via sysfs does it still try to move to the right
node? Same for resources allocated during ifup?

> > Since it wasn't clear to us that vzalloc_node() does any fallback,   
> 
> vzalloc_node() doesn't do fallback, but vzalloc will find the right node
> for you.

Sounds like we may want a vzalloc_node_with_fallback or some GFP flag?
All the _node() helpers which don't fall back lead to unpleasant code
in the users.

> > we followed the example in the ena driver to follow up with a more
> > generic vzalloc() request.  
> 
> I don't know about ENA implementation, maybe they have right reasons to
> do it, but maybe they don't.
> 
> > 
> > Also, the custom message helps us quickly figure out exactly which
> > allocation failed.  
> 
> If OOM is missing some info to help debug allocation failures, let's add
> it there, but please do not add any custom prints after alloc failures.

+1