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Subject: Re: [PATCH 5.4 000/168] 5.4.25-stable review
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     linux-kernel@vger.kernel.org, linux@roeck-us.net, shuah@kernel.org,
        stable@vger.kernel.org, Paolo Valente <paolo.valente@linaro.org>
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 <d97347d3-4eea-f5e1-8a3c-a12410e9ad5f@applied-asynchrony.com>
 <20200310143527.GB3376131@kroah.com>
From:   =?UTF-8?Q?Holger_Hoffst=c3=a4tte?= <holger@applied-asynchrony.com>
Organization: Applied Asynchrony, Inc.
Message-ID: <daf30758-fe28-0709-7908-91bb99ee5e39@applied-asynchrony.com>
Date:   Tue, 10 Mar 2020 15:51:01 +0100
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On 3/10/20 3:35 PM, Greg Kroah-Hartman wrote:
> On Tue, Mar 10, 2020 at 03:02:37PM +0100, Holger Hoffstätte wrote:
>> On 3/10/20 1:37 PM, Greg Kroah-Hartman wrote:
>>> This is the start of the stable review cycle for the 5.4.25 release.
>>
>> This fails to compile due to broken patch 001/168:
>> "block, bfq: get a ref to a group when adding it to a service tree":
>>
>> ..
>> block/bfq-wf2q.c: In function 'bfq_get_entity':
>> ./include/linux/kernel.h:994:51: error: 'struct bfq_group' has no member named 'entity'
>> ..
>>
>> The calls to bfq_get_entity::bfqg_and_blkg_get and bfq_forget_entity::bfqg_and_blkg_put
>> in bfq-wf2q.c need to be wrapped in #ifdef CONFIG_BFQ_GROUP_IOSCHED, otherwise
>> the build will fail when CONFIG_BFQ_GROUP_IOSCHED is not enabled.
>> This horribly error-prone #ifdef mess was finally removed in upstream commit
>> 4d8340d0d4d9. For 5.4 we'll either need that as well or add them back.
> 
> Ick, that's a mess.
> 
> I'll go drop that patch now, odd that it passed my build tests...

Uh, please no? It fixes a rather nasty UAF when cgroups are in use.
Please just add the other upstream commit as well, I confirmed it applies
cleanly and fixes the problem.

thanks,
Holger