Re: [PATCH v1] kernel/trace:check the val against the available mem

From: Steven Rostedt <rostedt@goodmis.org>
To: Matthew Wilcox <willy@infradead.org>
Cc: Joel Fernandes <joelaf@google.com>,
	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>
Subject: Re: [PATCH v1] kernel/trace:check the val against the available mem
Date: Thu, 5 Apr 2018 10:30:50 -0400	[thread overview]
Message-ID: <20180405103050.22f10319@gandalf.local.home> (raw)
In-Reply-To: <20180405142258.GA28128@bombadil.infradead.org>

On Thu, 5 Apr 2018 07:22:58 -0700
Matthew Wilcox <willy@infradead.org> wrote:

> 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?

Not sure what you mean by "more important"? Does saying "RETRY_MAYFAIL"
make it more important? The difference is, if GFP_KERNEL fails, we
don't want to trigger an OOM, and simply clean up and report -ENOMEM to
the user. It has nothing to do with being more important than other
allocations.

If there's 100 Megs of memory available, and the user requests a gig of
memory, it's going to fail. Ideally, it doesn't trigger OOM, but
instead simply reports -ENOMEM to the user.

-- Steve