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Date: Thu, 5 Apr 2018 07:22:58 -0700
From: Matthew Wilcox <willy@infradead.org>
Subject: Re: [PATCH v1] kernel/trace:check the val against the available mem
Message-ID: <20180405142258.GA28128@bombadil.infradead.org>
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To: Joel Fernandes <joelaf@google.com>
Cc: Steven Rostedt <rostedt@goodmis.org>, Michal Hocko <mhocko@kernel.org>, Zhaoyang Huang <huangzhaoyang@gmail.com>, Ingo Molnar <mingo@kernel.org>, LKML <linux-kernel@vger.kernel.org>, kernel-patch-test@lists.linaro.org, Andrew Morton <akpm@linux-foundation.org>, "open list:MEMORY MANAGEMENT" <linux-mm@kvack.org>, Vlastimil Babka <vbabka@suse.cz>

On Wed, Apr 04, 2018 at 09:12:52PM -0700, Joel Fernandes wrote:
> On Wed, Apr 4, 2018 at 7:58 PM, Matthew Wilcox <willy@infradead.org> wrote:
> > On Wed, Apr 04, 2018 at 11:47:30AM -0400, Steven Rostedt wrote:
> >> I originally was going to remove the RETRY_MAYFAIL, but adding this
> >> check (at the end of the loop though) appears to have OOM consistently
> >> kill this task.
> >>
> >> I still like to keep RETRY_MAYFAIL, because it wont trigger OOM if
> >> nothing comes in and tries to do an allocation, but instead will fail
> >> nicely with -ENOMEM.
> >
> > I still don't get why you want RETRY_MAYFAIL.  You know that tries
> > *harder* to allocate memory than plain GFP_KERNEL does, right?  And
> > that seems like the exact opposite of what you want.
> 
> No. We do want it to try harder but not if its already setup for failure.

I understand you don't want GFP_NORETRY.  But why is it more important for
this allocation to succeed than other normal GFP_KERNEL allocations?