[PATCH RESEND] selftests/damon: add damon to selftests root Makefile

[PATCH RESEND] selftests/damon: add damon to selftests root Makefile

[Yuanchu Xie]

Currently the damon selftests are not built with the rest of the
selftests. We add damon to the list of targets.

Fixes: b348eb7abd09 ("mm/damon: add user space selftests")
Reviewed-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Yuanchu Xie <yuanchu@google.com>
---
 tools/testing/selftests/Makefile | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index d08fe4cfe811..ffe453760a12 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile
@@ -9,6 +9,7 @@ TARGETS += clone3
 TARGETS += core
 TARGETS += cpufreq
 TARGETS += cpu-hotplug
+TARGETS += damon
 TARGETS += drivers/dma-buf
 TARGETS += efivarfs
 TARGETS += exec
-- 
2.35.1.265.g69c8d7142f-goog

Re: [PATCH RESEND] selftests/damon: add damon to selftests root Makefile

[David Rientjes]

On Mon, 18 Apr 2022, Yuanchu Xie wrote:

> Currently the damon selftests are not built with the rest of the
> selftests. We add damon to the list of targets.
> 
> Fixes: b348eb7abd09 ("mm/damon: add user space selftests")
> Reviewed-by: SeongJae Park <sj@kernel.org>
> Signed-off-by: Yuanchu Xie <yuanchu@google.com>

Acked-by: David Rientjes <rientjes@google.com>

Re: [PATCH RESEND] selftests/damon: add damon to selftests root Makefile

[Shuah Khan]

On 4/24/22 1:35 PM, David Rientjes wrote:
> On Mon, 18 Apr 2022, Yuanchu Xie wrote:
> 
>> Currently the damon selftests are not built with the rest of the
>> selftests. We add damon to the list of targets.
>>
>> Fixes: b348eb7abd09 ("mm/damon: add user space selftests")
>> Reviewed-by: SeongJae Park <sj@kernel.org>
>> Signed-off-by: Yuanchu Xie <yuanchu@google.com>
> 
> Acked-by: David Rientjes <rientjes@google.com>
> 

Thank you. Applied to linux-kselftest next for 5.19-rc1.

thanks,
-- Shuah

Re: [PATCH RESEND] selftests/damon: add damon to selftests root Makefile

[Shuah Khan]

On 4/25/22 1:37 PM, Shuah Khan wrote:
> On 4/24/22 1:35 PM, David Rientjes wrote:
>> On Mon, 18 Apr 2022, Yuanchu Xie wrote:
>>
>>> Currently the damon selftests are not built with the rest of the
>>> selftests. We add damon to the list of targets.
>>>
>>> Fixes: b348eb7abd09 ("mm/damon: add user space selftests")
>>> Reviewed-by: SeongJae Park <sj@kernel.org>
>>> Signed-off-by: Yuanchu Xie <yuanchu@google.com>
>>
>> Acked-by: David Rientjes <rientjes@google.com>
>>
> 
> Thank you. Applied to linux-kselftest next for 5.19-rc1.
> 

The test builds with warnings. Would you like to fix these as
well?

make
gcc     huge_count_read_write.c  -o linux_5.18/tools/testing/selftests/damon/huge_count_read_write
huge_count_read_write.c: In function ‘write_read_with_huge_count’:
huge_count_read_write.c:23:9: warning: ‘write’ reading 4294967295 bytes from a region of size 1 [-Wstringop-overread]
    23 |         write(filedesc, "", 0xfffffffful);
       |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from huge_count_read_write.c:8:
/usr/include/unistd.h:378:16: note: in a call to function ‘write’ declared with attribute ‘access (read_only, 2, 3)’
   378 | extern ssize_t write (int __fd, const void *__buf, size_t __n) __wur
       |                ^~~~~
huge_count_read_write.c:25:15: warning: ‘read’ writing 4294967295 bytes into a region of size 25 overflows the destination [-Wstringop-overflow=]
    25 |         ret = read(filedesc, buf, 0xfffffffful);
       |               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
huge_count_read_write.c:14:14: note: destination object ‘buf’ of size 25
    14 |         char buf[25];
       |              ^~~
In file included from huge_count_read_write.c:8:
/usr/include/unistd.h:371:16: note: in a call to function ‘read’ declared with attribute ‘access (write_only, 2, 3)’
   371 | extern ssize_t read (int __fd, void *__buf, size_t __nbytes) __wur
       |                ^~~~

thanks,
-- Shuah

[PATCH v2 1/2] selftests/damon: suppress compiler warnings for huge_count_read_write

[Yuanchu Xie]

The test case added in commit db7a347b26fe ("mm/damon/dbgfs:
use '__GFP_NOWARN' for user-specified size buffer allocation")
intentionally writes and reads with a large count to cause
allocation failure and check for kernel warnings. We suppress
the compiler warnings for these calls as they work as intended.

Signed-off-by: Yuanchu Xie <yuanchu@google.com>
---
 tools/testing/selftests/damon/Makefile | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/tools/testing/selftests/damon/Makefile b/tools/testing/selftests/damon/Makefile
index 0470c5f3e690..a300b4c5b373 100644
--- a/tools/testing/selftests/damon/Makefile
+++ b/tools/testing/selftests/damon/Makefile
@@ -1,6 +1,9 @@
 # SPDX-License-Identifier: GPL-2.0
 # Makefile for damon selftests
 
+CFLAGS += -Wno-stringop-overread
+CFLAGS += -Wno-stringop-overflow
+
 TEST_GEN_FILES += huge_count_read_write
 
 TEST_FILES = _chk_dependency.sh _debugfs_common.sh
-- 
2.36.0.464.gb9c8b46e94-goog

[PATCH v2 2/2] selftests/damon: add damon to selftests root Makefile

[Yuanchu Xie]

Currently the damon selftests are not built with the rest of the
selftests. We add damon to the list of targets.

Fixes: b348eb7abd09 ("mm/damon: add user space selftests")
Signed-off-by: Yuanchu Xie <yuanchu@google.com>
---
 tools/testing/selftests/Makefile | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index 2319ec87f53d..bd2ac8b3bf1f 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile
@@ -9,6 +9,7 @@ TARGETS += clone3
 TARGETS += core
 TARGETS += cpufreq
 TARGETS += cpu-hotplug
+TARGETS += damon
 TARGETS += drivers/dma-buf
 TARGETS += efivarfs
 TARGETS += exec
-- 
2.36.0.464.gb9c8b46e94-goog

Re: [PATCH v2 1/2] selftests/damon: suppress compiler warnings for huge_count_read_write

[SeongJae Park]

Hi Yuanchu, thank you for this patch!

On Wed, 4 May 2022 00:03:57 +0000 Yuanchu Xie <yuanchu@google.com> wrote:

> The test case added in commit db7a347b26fe ("mm/damon/dbgfs:
> use '__GFP_NOWARN' for user-specified size buffer allocation")
> intentionally writes and reads with a large count to cause
> allocation failure and check for kernel warnings. We suppress
> the compiler warnings for these calls as they work as intended.
> 
> Signed-off-by: Yuanchu Xie <yuanchu@google.com>

Reviewed-by: SeongJae Park <sj@kernel.org>


Thanks,
SJ

[...]
> ---
>  tools/testing/selftests/damon/Makefile | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/tools/testing/selftests/damon/Makefile b/tools/testing/selftests/damon/Makefile
> index 0470c5f3e690..a300b4c5b373 100644
> --- a/tools/testing/selftests/damon/Makefile
> +++ b/tools/testing/selftests/damon/Makefile
> @@ -1,6 +1,9 @@
>  # SPDX-License-Identifier: GPL-2.0
>  # Makefile for damon selftests
>  
> +CFLAGS += -Wno-stringop-overread
> +CFLAGS += -Wno-stringop-overflow
> +
>  TEST_GEN_FILES += huge_count_read_write
>  
>  TEST_FILES = _chk_dependency.sh _debugfs_common.sh
> -- 
> 2.36.0.464.gb9c8b46e94-goog
> 

Re: [PATCH v2 2/2] selftests/damon: add damon to selftests root Makefile

[SeongJae Park]

On Wed, 4 May 2022 00:03:58 +0000 Yuanchu Xie <yuanchu@google.com> wrote:

> Currently the damon selftests are not built with the rest of the
> selftests. We add damon to the list of targets.
> 
> Fixes: b348eb7abd09 ("mm/damon: add user space selftests")
> Signed-off-by: Yuanchu Xie <yuanchu@google.com>

Reviewed-by: SeongJae Park <sj@kernel.org>


Thanks,
SJ

> ---
>  tools/testing/selftests/Makefile | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
> index 2319ec87f53d..bd2ac8b3bf1f 100644
> --- a/tools/testing/selftests/Makefile
> +++ b/tools/testing/selftests/Makefile
> @@ -9,6 +9,7 @@ TARGETS += clone3
>  TARGETS += core
>  TARGETS += cpufreq
>  TARGETS += cpu-hotplug
> +TARGETS += damon
>  TARGETS += drivers/dma-buf
>  TARGETS += efivarfs
>  TARGETS += exec
> -- 
> 2.36.0.464.gb9c8b46e94-goog

Re: [PATCH v2 2/2] selftests/damon: add damon to selftests root Makefile

[David Rientjes]

On Wed, 4 May 2022, Yuanchu Xie wrote:

> Currently the damon selftests are not built with the rest of the
> selftests. We add damon to the list of targets.
> 
> Fixes: b348eb7abd09 ("mm/damon: add user space selftests")
> Signed-off-by: Yuanchu Xie <yuanchu@google.com>

Acked-by: David Rientjes <rientjes@google.com>

[PATCH v3] selftests/damon: suppress compiler warnings for huge_count_read_write

[Yuanchu Xie]

The test case added in commit db7a347b26fe ("mm/damon/dbgfs:
use '__GFP_NOWARN' for user-specified size buffer allocation")
intentionally writes and reads with a large count to cause
allocation failure and check for kernel warnings. We suppress
the compiler warnings for these calls as they work as intended.

Signed-off-by: Yuanchu Xie <yuanchu@google.com>
---
 tools/testing/selftests/damon/huge_count_read_write.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/tools/testing/selftests/damon/huge_count_read_write.c b/tools/testing/selftests/damon/huge_count_read_write.c
index ad7a6b4cf338..91bd80c75cd9 100644
--- a/tools/testing/selftests/damon/huge_count_read_write.c
+++ b/tools/testing/selftests/damon/huge_count_read_write.c
@@ -2,6 +2,8 @@
 /*
  * Author: SeongJae Park <sj@kernel.org>
  */
+#pragma GCC diagnostic ignored "-Wstringop-overflow"
+#pragma GCC diagnostic ignored "-Wstringop-overread"
 
 #include <fcntl.h>
 #include <stdlib.h>
-- 
2.36.0.464.gb9c8b46e94-goog

Re: [PATCH v3] selftests/damon: suppress compiler warnings for huge_count_read_write

[Yuanchu Xie]

Hi SeongJae,

Instead of adding the exception to the Makefile, these two pragmas can
be added to the offending c file instead. Although it is fairly minor and
either one works but I think this is cleaner.

Thanks,
Yuanchu

Re: [PATCH v3] selftests/damon: suppress compiler warnings for huge_count_read_write

[SeongJae Park]

Hi Yuanchu,

On Wed, 4 May 2022 18:29:08 +0000 Yuanchu Xie <yuanchu@google.com> wrote:

> The test case added in commit db7a347b26fe ("mm/damon/dbgfs:
> use '__GFP_NOWARN' for user-specified size buffer allocation")
> intentionally writes and reads with a large count to cause
> allocation failure and check for kernel warnings. We suppress
> the compiler warnings for these calls as they work as intended.
> 
> Signed-off-by: Yuanchu Xie <yuanchu@google.com>
> ---

It would be a good practice to mention the changes from the previous version of
this patch here[1].

[1] https://docs.kernel.org/process/submitting-patches.html#the-canonical-patch-format

>  tools/testing/selftests/damon/huge_count_read_write.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/tools/testing/selftests/damon/huge_count_read_write.c b/tools/testing/selftests/damon/huge_count_read_write.c
> index ad7a6b4cf338..91bd80c75cd9 100644
> --- a/tools/testing/selftests/damon/huge_count_read_write.c
> +++ b/tools/testing/selftests/damon/huge_count_read_write.c
> @@ -2,6 +2,8 @@
>  /*
>   * Author: SeongJae Park <sj@kernel.org>
>   */
> +#pragma GCC diagnostic ignored "-Wstringop-overflow"
> +#pragma GCC diagnostic ignored "-Wstringop-overread"

I agree that this must be the cleaner way than v2.  But, I get below warning
after applying this:

    $ sudo make -C tools/testing/selftests/damon run_tests
    make: Entering directory '/home/sjpark/linux/tools/testing/selftests/damon'
    gcc     huge_count_read_write.c  -o /home/sjpark/linux/tools/testing/selftests/damon/huge_count_read_write
    huge_count_read_write.c:6:32: warning: unknown option after ‘#pragma GCC diagnostic’ kind [-Wpragmas]
        6 | #pragma GCC diagnostic ignored "-Wstringop-overread"
          |                                ^~~~~~~~~~~~~~~~~~~~~

My gcc version is:

    $ gcc --version
    gcc (Ubuntu 9.4.0-1ubuntu1~20.04.1) 9.4.0


Thanks,
SJ

>  
>  #include <fcntl.h>
>  #include <stdlib.h>
> -- 
> 2.36.0.464.gb9c8b46e94-goog
> 

Re: [PATCH v3] selftests/damon: suppress compiler warnings for huge_count_read_write

[Yuanchu Xie]

Hi SeongJae,

On Wed, May 4, 2022 at 11:45 AM SeongJae Park <sj@kernel.org> wrote:
>
> Hi Yuanchu,
>
> On Wed, 4 May 2022 18:29:08 +0000 Yuanchu Xie <yuanchu@google.com> wrote:
>
> > The test case added in commit db7a347b26fe ("mm/damon/dbgfs:
> > use '__GFP_NOWARN' for user-specified size buffer allocation")
> > intentionally writes and reads with a large count to cause
> > allocation failure and check for kernel warnings. We suppress
> > the compiler warnings for these calls as they work as intended.
> >
> > Signed-off-by: Yuanchu Xie <yuanchu@google.com>
> > ---
>
> It would be a good practice to mention the changes from the previous version of
> this patch here[1].
>
> [1] https://docs.kernel.org/process/submitting-patches.html#the-canonical-patch-format
>
Thank you, I missed this when trying to figure out how to add
additional comments for a revision.

> >  tools/testing/selftests/damon/huge_count_read_write.c | 2 ++
> >  1 file changed, 2 insertions(+)
> >
> > diff --git a/tools/testing/selftests/damon/huge_count_read_write.c b/tools/testing/selftests/damon/huge_count_read_write.c
> > index ad7a6b4cf338..91bd80c75cd9 100644
> > --- a/tools/testing/selftests/damon/huge_count_read_write.c
> > +++ b/tools/testing/selftests/damon/huge_count_read_write.c
> > @@ -2,6 +2,8 @@
> >  /*
> >   * Author: SeongJae Park <sj@kernel.org>
> >   */
> > +#pragma GCC diagnostic ignored "-Wstringop-overflow"
> > +#pragma GCC diagnostic ignored "-Wstringop-overread"
>
> I agree that this must be the cleaner way than v2.  But, I get below warning
> after applying this:
>
>     $ sudo make -C tools/testing/selftests/damon run_tests
>     make: Entering directory '/home/sjpark/linux/tools/testing/selftests/damon'
>     gcc     huge_count_read_write.c  -o /home/sjpark/linux/tools/testing/selftests/damon/huge_count_read_write
>     huge_count_read_write.c:6:32: warning: unknown option after ‘#pragma GCC diagnostic’ kind [-Wpragmas]
>         6 | #pragma GCC diagnostic ignored "-Wstringop-overread"
>           |                                ^~~~~~~~~~~~~~~~~~~~~
>
> My gcc version is:
>
>     $ gcc --version
>     gcc (Ubuntu 9.4.0-1ubuntu1~20.04.1) 9.4.0
I see, I'm running

    $ gcc --version
    gcc (Debian 11.2.0-16+build1) 11.2.0

I believe this is a new warning for gcc-11 [1], and somewhat
unfortunate that it results in a warning for gcc-9.4. I'm not sure
what the preference is here.
[1] https://gcc.gnu.org/onlinedocs/gcc-10.3.0/gcc/Warning-Options.html

Thanks,
Yuanchu

Re: [PATCH v3] selftests/damon: suppress compiler warnings for huge_count_read_write

[Yuanchu Xie]

SeongJae,

Do you have a preference on how this should be handled?

Thanks,
Yuanchu

On Wed, May 4, 2022 at 6:12 PM Yuanchu Xie <yuanchu@google.com> wrote:
>
> Hi SeongJae,
>
> On Wed, May 4, 2022 at 11:45 AM SeongJae Park <sj@kernel.org> wrote:
> >
> > Hi Yuanchu,
> >
> > On Wed, 4 May 2022 18:29:08 +0000 Yuanchu Xie <yuanchu@google.com> wrote:
> >
> > > The test case added in commit db7a347b26fe ("mm/damon/dbgfs:
> > > use '__GFP_NOWARN' for user-specified size buffer allocation")
> > > intentionally writes and reads with a large count to cause
> > > allocation failure and check for kernel warnings. We suppress
> > > the compiler warnings for these calls as they work as intended.
> > >
> > > Signed-off-by: Yuanchu Xie <yuanchu@google.com>
> > > ---
> >
> > It would be a good practice to mention the changes from the previous version of
> > this patch here[1].
> >
> > [1] https://docs.kernel.org/process/submitting-patches.html#the-canonical-patch-format
> >
> Thank you, I missed this when trying to figure out how to add
> additional comments for a revision.
>
> > >  tools/testing/selftests/damon/huge_count_read_write.c | 2 ++
> > >  1 file changed, 2 insertions(+)
> > >
> > > diff --git a/tools/testing/selftests/damon/huge_count_read_write.c b/tools/testing/selftests/damon/huge_count_read_write.c
> > > index ad7a6b4cf338..91bd80c75cd9 100644
> > > --- a/tools/testing/selftests/damon/huge_count_read_write.c
> > > +++ b/tools/testing/selftests/damon/huge_count_read_write.c
> > > @@ -2,6 +2,8 @@
> > >  /*
> > >   * Author: SeongJae Park <sj@kernel.org>
> > >   */
> > > +#pragma GCC diagnostic ignored "-Wstringop-overflow"
> > > +#pragma GCC diagnostic ignored "-Wstringop-overread"
> >
> > I agree that this must be the cleaner way than v2.  But, I get below warning
> > after applying this:
> >
> >     $ sudo make -C tools/testing/selftests/damon run_tests
> >     make: Entering directory '/home/sjpark/linux/tools/testing/selftests/damon'
> >     gcc     huge_count_read_write.c  -o /home/sjpark/linux/tools/testing/selftests/damon/huge_count_read_write
> >     huge_count_read_write.c:6:32: warning: unknown option after ‘#pragma GCC diagnostic’ kind [-Wpragmas]
> >         6 | #pragma GCC diagnostic ignored "-Wstringop-overread"
> >           |                                ^~~~~~~~~~~~~~~~~~~~~
> >
> > My gcc version is:
> >
> >     $ gcc --version
> >     gcc (Ubuntu 9.4.0-1ubuntu1~20.04.1) 9.4.0
> I see, I'm running
>
>     $ gcc --version
>     gcc (Debian 11.2.0-16+build1) 11.2.0
>
> I believe this is a new warning for gcc-11 [1], and somewhat
> unfortunate that it results in a warning for gcc-9.4. I'm not sure
> what the preference is here.
> [1] https://gcc.gnu.org/onlinedocs/gcc-10.3.0/gcc/Warning-Options.html
>
> Thanks,
> Yuanchu

Re: [PATCH v3] selftests/damon: suppress compiler warnings for huge_count_read_write

[SeongJae Park]

Hi Yuanchu,

On Mon, 16 May 2022 21:07:25 -0400 Yuanchu Xie <yuanchu@google.com> wrote:

> SeongJae,
> 
> Do you have a preference on how this should be handled?

Sorry for late response.  I was thinking you were asking Shuah's opinion.  I
have no strong opinion but the approach you made in v2 looks slightly better
for me.


Thanks,
SJ

> 
> Thanks,
> Yuanchu
> 
> On Wed, May 4, 2022 at 6:12 PM Yuanchu Xie <yuanchu@google.com> wrote:
> >
> > Hi SeongJae,
> >
> > On Wed, May 4, 2022 at 11:45 AM SeongJae Park <sj@kernel.org> wrote:
> > >
> > > Hi Yuanchu,
> > >
> > > On Wed, 4 May 2022 18:29:08 +0000 Yuanchu Xie <yuanchu@google.com> wrote:
> > >
> > > > The test case added in commit db7a347b26fe ("mm/damon/dbgfs:
> > > > use '__GFP_NOWARN' for user-specified size buffer allocation")
> > > > intentionally writes and reads with a large count to cause
> > > > allocation failure and check for kernel warnings. We suppress
> > > > the compiler warnings for these calls as they work as intended.
> > > >
> > > > Signed-off-by: Yuanchu Xie <yuanchu@google.com>
> > > > ---
> > >
> > > It would be a good practice to mention the changes from the previous version of
> > > this patch here[1].
> > >
> > > [1] https://docs.kernel.org/process/submitting-patches.html#the-canonical-patch-format
> > >
> > Thank you, I missed this when trying to figure out how to add
> > additional comments for a revision.
> >
> > > >  tools/testing/selftests/damon/huge_count_read_write.c | 2 ++
> > > >  1 file changed, 2 insertions(+)
> > > >
> > > > diff --git a/tools/testing/selftests/damon/huge_count_read_write.c b/tools/testing/selftests/damon/huge_count_read_write.c
> > > > index ad7a6b4cf338..91bd80c75cd9 100644
> > > > --- a/tools/testing/selftests/damon/huge_count_read_write.c
> > > > +++ b/tools/testing/selftests/damon/huge_count_read_write.c
> > > > @@ -2,6 +2,8 @@
> > > >  /*
> > > >   * Author: SeongJae Park <sj@kernel.org>
> > > >   */
> > > > +#pragma GCC diagnostic ignored "-Wstringop-overflow"
> > > > +#pragma GCC diagnostic ignored "-Wstringop-overread"
> > >
> > > I agree that this must be the cleaner way than v2.  But, I get below warning
> > > after applying this:
> > >
> > >     $ sudo make -C tools/testing/selftests/damon run_tests
> > >     make: Entering directory '/home/sjpark/linux/tools/testing/selftests/damon'
> > >     gcc     huge_count_read_write.c  -o /home/sjpark/linux/tools/testing/selftests/damon/huge_count_read_write
> > >     huge_count_read_write.c:6:32: warning: unknown option after ‘#pragma GCC diagnostic’ kind [-Wpragmas]
> > >         6 | #pragma GCC diagnostic ignored "-Wstringop-overread"
> > >           |                                ^~~~~~~~~~~~~~~~~~~~~
> > >
> > > My gcc version is:
> > >
> > >     $ gcc --version
> > >     gcc (Ubuntu 9.4.0-1ubuntu1~20.04.1) 9.4.0
> > I see, I'm running
> >
> >     $ gcc --version
> >     gcc (Debian 11.2.0-16+build1) 11.2.0
> >
> > I believe this is a new warning for gcc-11 [1], and somewhat
> > unfortunate that it results in a warning for gcc-9.4. I'm not sure
> > what the preference is here.
> > [1] https://gcc.gnu.org/onlinedocs/gcc-10.3.0/gcc/Warning-Options.html
> >
> > Thanks,
> > Yuanchu
> 

Re: [PATCH v3] selftests/damon: suppress compiler warnings for huge_count_read_write

[Yuanchu Xie]

Hi Shuah,

On Wed, May 4, 2022 at 11:45 AM SeongJae Park <sj@kernel.org> wrote:
>
> Hi Yuanchu,
>
> On Wed, 4 May 2022 18:29:08 +0000 Yuanchu Xie <yuanchu@google.com> wrote:
>
> > The test case added in commit db7a347b26fe ("mm/damon/dbgfs:
> > use '__GFP_NOWARN' for user-specified size buffer allocation")
> > intentionally writes and reads with a large count to cause
> > allocation failure and check for kernel warnings. We suppress
> > the compiler warnings for these calls as they work as intended.
> >
> > Signed-off-by: Yuanchu Xie <yuanchu@google.com>
> > ---
>
> It would be a good practice to mention the changes from the previous version of
> this patch here[1].
>
> [1] https://docs.kernel.org/process/submitting-patches.html#the-canonical-patch-format
>
> >  tools/testing/selftests/damon/huge_count_read_write.c | 2 ++
> >  1 file changed, 2 insertions(+)
> >
> > diff --git a/tools/testing/selftests/damon/huge_count_read_write.c b/tools/testing/selftests/damon/huge_count_read_write.c
> > index ad7a6b4cf338..91bd80c75cd9 100644
> > --- a/tools/testing/selftests/damon/huge_count_read_write.c
> > +++ b/tools/testing/selftests/damon/huge_count_read_write.c
> > @@ -2,6 +2,8 @@
> >  /*
> >   * Author: SeongJae Park <sj@kernel.org>
> >   */
> > +#pragma GCC diagnostic ignored "-Wstringop-overflow"
> > +#pragma GCC diagnostic ignored "-Wstringop-overread"
>
> I agree that this must be the cleaner way than v2.  But, I get below warning
> after applying this:
>
>     $ sudo make -C tools/testing/selftests/damon run_tests
>     make: Entering directory '/home/sjpark/linux/tools/testing/selftests/damon'
>     gcc     huge_count_read_write.c  -o /home/sjpark/linux/tools/testing/selftests/damon/huge_count_read_write
>     huge_count_read_write.c:6:32: warning: unknown option after ‘#pragma GCC diagnostic’ kind [-Wpragmas]
>         6 | #pragma GCC diagnostic ignored "-Wstringop-overread"
>           |                                ^~~~~~~~~~~~~~~~~~~~~
>
> My gcc version is:
>
>     $ gcc --version
>     gcc (Ubuntu 9.4.0-1ubuntu1~20.04.1) 9.4.0

    $ gcc --version
    gcc (Debian 11.2.0-16+build1) 11.2.0

I believe this is a new warning for gcc-11 [1], and somewhat unfortunate that
it results in a warning for gcc-9.4. So a patch that would resolve the test
warnings for gcc 11 would introduce a new warning for gcc 9, and vice versa.
What's the preferred solution here?

[1] https://gcc.gnu.org/onlinedocs/gcc-10.3.0/gcc/Warning-Options.html

Thanks,
Yuanchu