Re: [linux-next:master 9995/11651] fs/buffer.c:2254:5: warning: stack frame size (2144) exceeds limit (1024) in 'block_read_full_folio'

Re: [linux-next:master 9995/11651] fs/buffer.c:2254:5: warning: stack frame size (2144) exceeds limit (1024) in 'block_read_full_folio'

[Nathan Chancellor]

On Sat, May 14, 2022 at 05:28:33PM +0100, Matthew Wilcox wrote:
> On Sun, May 15, 2022 at 12:23:46AM +0800, kernel test robot wrote:
> > commit: 2c69e2057962b6bd76d72446453862eb59325b49 [9995/11651] fs: Convert block_read_full_page() to block_read_full_folio()
> > config: hexagon-randconfig-r041-20220513 (https://download.01.org/0day-ci/archive/20220515/202205150051.3RzuooAG-lkp@intel.com/config)
> > compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project 38189438b69ca27b4c6ce707c52dbd217583d046)
> ...
> > All warnings (new ones prefixed by >>):
> > 
> > >> fs/buffer.c:2254:5: warning: stack frame size (2144) exceeds limit (1024) in 'block_read_full_folio' [-Wframe-larger-than]
> >    int block_read_full_folio(struct folio *folio, get_block_t *get_block)
> >        ^
> >    1 warning generated.
> 
> Now show the warnings that were removed.  This patch renames the
> function, and I bet there was a similar warning before this patch.
> 
> But basically, I don't care about stack usage on hexagon with clang.
> AIUI, it's a known bug.

For what it's worth, it seems like this is just 256K pages being 256K
pages... MAX_BUF_PER_PAGE is PAGE_SIZE / 512 so *arr is 2048 bytes big
in this configuration. You'd see a similar warning with PowerPC but that
configuration is non-standard:

fs/buffer.c: In function ‘block_read_full_page’:
fs/buffer.c:2337:1: warning: the frame size of 2064 bytes is larger than 1024 bytes [-Wframe-larger-than=]
 2337 | }
      | ^

It would be nice if the Intel folks could look at recognizing a function
rename so that you are not bothered by reports like this.

As a side note... Brian, is there any reason for 256K pages to exist for
Hexagon? This has been an option since Hexagon's introduction but is it
actually used? 4K pages is the default and the help text says "use with
caution". Perhaps the choice should be turned off altogether for
CONFIG_COMPILE_TEST so that we cannot select this configuration and
bother developers with these reports.

Cheers,
Nathan

Re: [linux-next:master 9995/11651] fs/buffer.c:2254:5: warning: stack frame size (2144) exceeds limit (1024) in 'block_read_full_folio'

[Matthew Wilcox]

On Sat, May 14, 2022 at 02:57:18PM -0700, Nathan Chancellor wrote:
> On Sat, May 14, 2022 at 05:28:33PM +0100, Matthew Wilcox wrote:
> > On Sun, May 15, 2022 at 12:23:46AM +0800, kernel test robot wrote:
> > > commit: 2c69e2057962b6bd76d72446453862eb59325b49 [9995/11651] fs: Convert block_read_full_page() to block_read_full_folio()
> > > config: hexagon-randconfig-r041-20220513 (https://download.01.org/0day-ci/archive/20220515/202205150051.3RzuooAG-lkp@intel.com/config)
> > > compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project 38189438b69ca27b4c6ce707c52dbd217583d046)
> > ...
> > > All warnings (new ones prefixed by >>):
> > > 
> > > >> fs/buffer.c:2254:5: warning: stack frame size (2144) exceeds limit (1024) in 'block_read_full_folio' [-Wframe-larger-than]
> > >    int block_read_full_folio(struct folio *folio, get_block_t *get_block)
> > >        ^
> > >    1 warning generated.
> > 
> > Now show the warnings that were removed.  This patch renames the
> > function, and I bet there was a similar warning before this patch.
> > 
> > But basically, I don't care about stack usage on hexagon with clang.
> > AIUI, it's a known bug.
> 
> For what it's worth, it seems like this is just 256K pages being 256K
> pages... MAX_BUF_PER_PAGE is PAGE_SIZE / 512 so *arr is 2048 bytes big
> in this configuration. You'd see a similar warning with PowerPC but that
> configuration is non-standard:

Ahh!  Yes, I'd forgotten that Hexagon has that crazy config option.
I think I can get rid of that enormous array of pointers, it just wasn't
a high priority for me.

> fs/buffer.c: In function ‘block_read_full_page’:
> fs/buffer.c:2337:1: warning: the frame size of 2064 bytes is larger than 1024 bytes [-Wframe-larger-than=]
>  2337 | }
>       | ^
> 
> It would be nice if the Intel folks could look at recognizing a function
> rename so that you are not bothered by reports like this.
> 
> As a side note... Brian, is there any reason for 256K pages to exist for
> Hexagon? This has been an option since Hexagon's introduction but is it
> actually used? 4K pages is the default and the help text says "use with
> caution". Perhaps the choice should be turned off altogether for
> CONFIG_COMPILE_TEST so that we cannot select this configuration and
> bother developers with these reports.
> 
> Cheers,
> Nathan

Re: [kbuild-all] Re: [linux-next:master 9995/11651] fs/buffer.c:2254:5: warning: stack frame size (2144) exceeds limit (1024) in 'block_read_full_folio'

[Chen, Rong A]

On 5/15/2022 5:57 AM, Nathan Chancellor wrote:
> On Sat, May 14, 2022 at 05:28:33PM +0100, Matthew Wilcox wrote:
>> On Sun, May 15, 2022 at 12:23:46AM +0800, kernel test robot wrote:
>>> commit: 2c69e2057962b6bd76d72446453862eb59325b49 [9995/11651] fs: Convert block_read_full_page() to block_read_full_folio()
>>> config: hexagon-randconfig-r041-20220513 (https://download.01.org/0day-ci/archive/20220515/202205150051.3RzuooAG-lkp@intel.com/config)
>>> compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project 38189438b69ca27b4c6ce707c52dbd217583d046)
>> ...
>>> All warnings (new ones prefixed by >>):
>>>
>>>>> fs/buffer.c:2254:5: warning: stack frame size (2144) exceeds limit (1024) in 'block_read_full_folio' [-Wframe-larger-than]
>>>     int block_read_full_folio(struct folio *folio, get_block_t *get_block)
>>>         ^
>>>     1 warning generated.
>>
>> Now show the warnings that were removed.  This patch renames the
>> function, and I bet there was a similar warning before this patch.
>>
>> But basically, I don't care about stack usage on hexagon with clang.
>> AIUI, it's a known bug.
> 
> For what it's worth, it seems like this is just 256K pages being 256K
> pages... MAX_BUF_PER_PAGE is PAGE_SIZE / 512 so *arr is 2048 bytes big
> in this configuration. You'd see a similar warning with PowerPC but that
> configuration is non-standard:
> 
> fs/buffer.c: In function ‘block_read_full_page’:
> fs/buffer.c:2337:1: warning: the frame size of 2064 bytes is larger than 1024 bytes [-Wframe-larger-than=]
>   2337 | }
>        | ^
> 
> It would be nice if the Intel folks could look at recognizing a function
> rename so that you are not bothered by reports like this.

Hi Nathan, Matthew,

Sorry about this, we'll take a look.

Best Regards,
Rong Chen


> 
> As a side note... Brian, is there any reason for 256K pages to exist for
> Hexagon? This has been an option since Hexagon's introduction but is it
> actually used? 4K pages is the default and the help text says "use with
> caution". Perhaps the choice should be turned off altogether for
> CONFIG_COMPILE_TEST so that we cannot select this configuration and
> bother developers with these reports.
> 
> Cheers,
> Nathan
> _______________________________________________
> kbuild-all mailing list -- kbuild-all@lists.01.org
> To unsubscribe send an email to kbuild-all-leave@lists.01.org
> 

RE: [linux-next:master 9995/11651] fs/buffer.c:2254:5: warning: stack frame size (2144) exceeds limit (1024) in 'block_read_full_folio'

[Brian Cain]

> -----Original Message-----
> From: Nathan Chancellor <nathan@kernel.org>
...
> As a side note... Brian, is there any reason for 256K pages to exist for
> Hexagon? This has been an option since Hexagon's introduction but is it
> actually used? 4K pages is the default and the help text says "use with
> caution". Perhaps the choice should be turned off altogether for
> CONFIG_COMPILE_TEST so that we cannot select this configuration and
> bother developers with these reports.

It's not the most commonly used page size, yeah.  Ok, we will disable it for CONFIG_COMPILE_TEST.

-Brian

Re: [linux-next:master 9995/11651] fs/buffer.c:2254:5: warning: stack frame size (2144) exceeds limit (1024) in 'block_read_full_folio'

[Matthew Wilcox]

On Tue, May 17, 2022 at 04:16:45AM +0000, Brian Cain wrote:
> > -----Original Message-----
> > From: Nathan Chancellor <nathan@kernel.org>
> ...
> > As a side note... Brian, is there any reason for 256K pages to exist for
> > Hexagon? This has been an option since Hexagon's introduction but is it
> > actually used? 4K pages is the default and the help text says "use with
> > caution". Perhaps the choice should be turned off altogether for
> > CONFIG_COMPILE_TEST so that we cannot select this configuration and
> > bother developers with these reports.
> 
> It's not the most commonly used page size, yeah.  Ok, we will disable it for CONFIG_COMPILE_TEST.

Maybe the stack size limit could be raised for 256KB page size?
Presumably the minimum stack size is 256KB, so it's not a problem for an
individual function to consume 16KB of stack space?