linux-kernel - Re: linux-next: Tree for Dec 6 (objtool, lots in btrfs)

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Message-ID: <ba2a7a9b-933b-d4e4-8970-85b6c1291fca@infradead.org>
Date:   Fri, 13 Dec 2019 15:03:11 -0800
From:   Randy Dunlap <rdunlap@...radead.org>
To:     Josh Poimboeuf <jpoimboe@...hat.com>
Cc:     dsterba@...e.cz, Stephen Rothwell <sfr@...b.auug.org.au>,
        Linux Next Mailing List <linux-next@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux Btrfs <linux-btrfs@...r.kernel.org>,
        Peter Zijlstra <peterz@...radead.org>
Subject: Re: linux-next: Tree for Dec 6 (objtool, lots in btrfs)

On 12/12/19 12:25 PM, Randy Dunlap wrote:
> On 12/12/19 10:47 AM, Josh Poimboeuf wrote:
>> On Wed, Dec 11, 2019 at 08:21:38AM -0800, Randy Dunlap wrote:
>>> [oops, forgot to add Josh and PeterZ]
>>>
>>> On 12/11/19 5:49 AM, David Sterba wrote:
>>>> On Fri, Dec 06, 2019 at 08:17:30AM -0800, Randy Dunlap wrote:
>>>>> On 12/5/19 6:54 PM, Stephen Rothwell wrote:
>>>>>> Hi all,
>>>>>>
>>>>>> Please do not add any material for v5.6 to your linux-next included
>>>>>> trees until after v5.5-rc1 has been released.
>>>>>>
>>>>>> Changes since 20191204:
>>>>>>
>>>>>
>>>>> on x86_64:
>>>>>
>>>>> fs/btrfs/ctree.o: warning: objtool: btrfs_search_slot()+0x2d4: unreachable instruction
>>>>
>>>> Can somebody enlighten me what is one supposed to do to address the
>>>> warnings? Function names reported in the list contain our ASSERT macro
>>>> that conditionally calls BUG() that I believe is what could cause the
>>>> unreachable instructions but I don't see how.
>>>>
>>>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/fs/btrfs/ctree.h#n3113
>>>>
>>>> __cold
>>>> static inline void assfail(const char *expr, const char *file, int line)
>>>> {
>>>> 	if (IS_ENABLED(CONFIG_BTRFS_ASSERT)) {
>>>> 		pr_err("assertion failed: %s, in %s:%d\n", expr, file, line);
>>>> 		BUG();
>>>> 	}
>>>> }
>>>>
>>>> #define ASSERT(expr)	\
>>>> 	(likely(expr) ? (void)0 : assfail(#expr, __FILE__, __LINE__))
>>>>
>>
>> Randy, can you share one of the btrfs .o files?  I'm not able to
>> recreate.
>>
> 
> Hm. I'll have to try to recreate this. I no longer have files from 20191206
> (lack of space).
> 
> I'll let you know if/when I can recreate it.

OK, 40 builds later, I have reproduced it.

I am attaching one of the btrfs .o files and the kernel config file (FTR).
(gzipped)
Let me know if you want more of the .o files.

thanks.
-- 
~Randy


View attachment "config-r8865" of type "text/plain" (119365 bytes)

Download attachment "ctree.o.gz" of type "application/gzip" (86646 bytes)