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

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Message-ID: <4b4eb1f9-440c-f4cd-942c-2c11b566c4c0@linux.alibaba.com>
Date:   Sun, 14 Jul 2019 20:47:07 -0700
From:   Yang Shi <yang.shi@...ux.alibaba.com>
To:     Matthew Wilcox <willy@...radead.org>
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 7/13/19 2:25 PM, Matthew Wilcox wrote:
> 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.

Do you mean kmemleak internal allocation? It would fail even though 
__GFP_NOFAIL is passed in if GFP_NOWAIT is specified. Currently buddy 
allocator will not retry if the allocation is non-blockable.