linux-kernel - Re: [PATCH] scsi: libcxgbi: use kvzalloc instead of opencoded kzalloc/vzalloc

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Message-ID: <0c1803c6aaca42579b7933fd219e4e208ab7524f.camel@perches.com>
Date:   Sat, 01 Aug 2020 01:10:28 -0700
From:   Joe Perches <joe@...ches.com>
To:     Denis Efremov <efremov@...ux.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>
Cc:     linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] scsi: libcxgbi: use kvzalloc instead of opencoded
 kzalloc/vzalloc

On Sat, 2020-08-01 at 10:51 +0300, Denis Efremov wrote:
> On 8/1/20 1:24 AM, Joe Perches wrote:
> > On Sat, 2020-08-01 at 01:10 +0300, Denis Efremov wrote:
> > > On 8/1/20 12:58 AM, Joe Perches wrote:
> > > > On Sat, 2020-08-01 at 00:55 +0300, Denis Efremov wrote:
> > > > > Remove cxgbi_alloc_big_mem(), cxgbi_free_big_mem() functions
> > > > > and use kvzalloc/kvfree instead.
> > > > 
> > > > Sensible, thanks.
> > > > 
> > > > > diff --git a/drivers/scsi/cxgbi/libcxgbi.c b/drivers/scsi/cxgbi/libcxgbi.c
> > > > []
> > > > > @@ -77,9 +77,9 @@ int cxgbi_device_portmap_create(struct cxgbi_device *cdev, unsigned int base,
> > > > >  {
> > > > >  	struct cxgbi_ports_map *pmap = &cdev->pmap;
> > > > >  
> > > > > -	pmap->port_csk = cxgbi_alloc_big_mem(max_conn *
> > > > > -					     sizeof(struct cxgbi_sock *),
> > > > > -					     GFP_KERNEL);
> > > > > +	pmap->port_csk = kvzalloc(array_size(max_conn,
> > > > > +					     sizeof(struct cxgbi_sock *)),
> > > > > +				  GFP_KERNEL);
> > > > 
> > > > missing __GFP_NOWARN
> > > > 
> > > 
> > > kvmalloc_node adds __GFP_NOWARN internally to kmalloc call
> > > https://elixir.bootlin.com/linux/v5.8-rc4/source/mm/util.c#L568
> > 
> > Only when there's a fallback, and the fallback does not.
> Sorry, Joe, I don't understand why do we need to add __GFP_NOWARN here.

Hi.

The reason to add __GFP_NOWARN is so you don't get a
dump_stack() as there's an existing error message
output below this when OOM.

You should either remove the error message as it just
effectively duplicates the dump_stack or add __GFP_NOWARN.

Your choice.

cheers, Joe