linux-kernel - Re: [PATCH] mm: page_alloc: document kmemleak's non-blockable __GFP

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Message-ID: <20190713212548.GZ32320@bombadil.infradead.org>
Date:   Sat, 13 Jul 2019 14:25:48 -0700
From:   Matthew Wilcox <willy@...radead.org>
To:     Yang Shi <yang.shi@...ux.alibaba.com>
Cc:     mhocko@...e.com, dvyukov@...gle.com, catalin.marinas@....com,
        akpm@...ux-foundation.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm: page_alloc: document kmemleak's non-blockable
 __GFP_NOFAIL case

On Sat, Jul 13, 2019 at 04:49:04AM +0800, Yang Shi wrote:
> When running ltp's oom test with kmemleak enabled, the below warning was
> triggerred since kernel detects __GFP_NOFAIL & ~__GFP_DIRECT_RECLAIM is
> passed in:

There are lots of places where kmemleak will call kmalloc with
__GFP_NOFAIL and ~__GFP_DIRECT_RECLAIM (including the XArray code, which
is how I know about it).  It needs to be fixed to allow its internal
allocations to fail and return failure of the original allocation as
a consequence.