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From: David Disseldorp <ddiss@suse.de>
To: target-devel@vger.kernel.org
Subject: Re: [PATCH 02/10] target/core: Use kvcalloc() instead of open-coding it
Date: Fri, 16 Nov 2018 17:02:43 +0000	[thread overview]
Message-ID: <20181116180243.7ad1562e@suse.de> (raw)
In-Reply-To: <20181106171718.89594-3-bvanassche@acm.org>

On Fri, 16 Nov 2018 07:58:41 -0800, Bart Van Assche wrote:

> On Fri, 2018-11-16 at 14:10 +0100, David Disseldorp wrote:
> > On Thu, 08 Nov 2018 15:17:45 -0800, Bart Van Assche wrote:  
> > > What makes you think that I dropped any of the __GFP flags? The only purpose
> > > of the __GFP_NOWARN and __GFP_RETRY_MAYFAIL flags is to make kcalloc() fail
> > > quickly and silently.  
> > 
> > Are you confusing __GFP_RETRY_MAYFAIL with __GFP_NORETRY here?  
> 
> No. Passing __GFP_RETRY_MAYFAIL to a memory allocation function makes the memory
> allocator try less hard than without that flag.

In the context of this patch we're going from __GFP_RETRY_MAYFAIL to
__GFP_NORETRY (due to the  kvmalloc_node() >PAGE_SIZE logic), so "fail
quickly" makes more sense to me when referring to the latter.

> > > I'm not dropping these flags: as one can see in the
> > > kvmalloc_node() implementation that function passes these flags to
> > > kmalloc_node(). The source code I'm referring to is available in mm/util.c.  
> > 
> > I see that (given tag_num * tag_size > PAGE_SIZE) __GFP_NOWARN is added
> > by kvmalloc_node(), but __GFP_RETRY_MAYFAIL is dropped with your change,
> > which sees __GFP_NORETRY added in the >PAGE_SIZE path.  
> 
> That's right. If you want I can mention this in the patch description.

I don't think that's needed, I was just interested in the motivation for
the change in __GFP flags.

Cheers, David

      parent reply	other threads:[~2018-11-16 17:02 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-06 17:17 [PATCH 02/10] target/core: Use kvcalloc() instead of open-coding it Bart Van Assche
2018-11-08 12:54 ` David Disseldorp
2018-11-08 23:17 ` Bart Van Assche
2018-11-16 13:10 ` David Disseldorp
2018-11-16 15:58 ` Bart Van Assche
2018-11-16 17:02 ` David Disseldorp [this message]

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