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Message-ID: <0fd0c72d-badc-ad75-f0fe-91bc148820f2@bytedance.com>
Date: Tue, 8 Nov 2022 10:47:58 +0800
From: Qi Zheng <zhengqi.arch@...edance.com>
To: Jason Gunthorpe <jgg@...dia.com>
Cc: dvyukov@...gle.com, willy@...radead.org, akinobu.mita@...il.com,
akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
linux-mm@...ck.org, linux-fsdevel@...r.kernel.org,
stable@...r.kernel.org
Subject: Re: [PATCH] mm: fix unexpected changes to
{failslab|fail_page_alloc}.attr
On 2022/11/8 00:26, Jason Gunthorpe wrote:
> On Mon, Nov 07, 2022 at 11:05:42PM +0800, Qi Zheng wrote:
>>
>>
>> On 2022/11/7 20:42, Jason Gunthorpe wrote:
>>> On Mon, Nov 07, 2022 at 11:31:09AM +0800, Qi Zheng wrote:
>>>
>>>> @@ -31,9 +33,9 @@ bool __should_failslab(struct kmem_cache *s, gfp_t gfpflags)
>>>> return false;
>>>> if (gfpflags & __GFP_NOWARN)
>>>> - failslab.attr.no_warn = true;
>>>> + flags |= FAULT_NOWARN;
>>>
>>> You should add a comment here about why this is required, to avoid
>>> deadlocking printk
>>
>> I think this comment should be placed where __GFP_NOWARN is specified
>> instead of here. What do you think? :)
>
> NOWARN is clear what it does, it is this specifically that is very
> subtle about avoiding deadlock aginst allocations triggered by
> printk/etc code.
Oh, maybe I understand your concern. Some people may think that this
is just a print of fault injection information, not a warning. I'll
add a comment explaining why in some cases there must be no printing.
Thanks,
Qi
>
> Jason
--
Thanks,
Qi
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