linux-kernel - Re: [RFC PATCH] docs/core-api: add memory allocation guide

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Message-ID: <20180815093032.GQ32645@dhcp22.suse.cz>
Date:   Wed, 15 Aug 2018 11:30:32 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     Mike Rapoport <rppt@...ux.vnet.ibm.com>
Cc:     linux-mm@...ck.org, Jonathan Corbet <corbet@....net>,
        Matthew Wilcox <willy@...radead.org>,
        Vlastimil Babka <vbabka@...e.cz>, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH] docs/core-api: add memory allocation guide

On Wed 15-08-18 12:04:29, Mike Rapoport wrote:
[...]
> How about:
> 
> * If the allocation is performed from an atomic context, e.g interrupt
>   handler, use ``GFP_NOWARN``. This flag prevents direct reclaim and IO or
>   filesystem operations. Consequently, under memory pressure ``GFP_NOWARN``
>   allocation is likely to fail.

s@...ARN@...AIT@ I guess. Looks good otherwise. I would even go and
mention GFP_NOWARN once you brought it up. Allocations which have a
reasonable fallback should be using NOWARN.

> * If you think that accessing memory reserves is justified and the kernel
>   will be stressed unless allocation succeeds, you may use ``GFP_ATOMIC``.

OK otherwise.
-- 
Michal Hocko
SUSE Labs