[PATCH] [v2] mm: shmem: avoid build warning for CONFIG_SHMEM=n

[PATCH] [v2] mm: shmem: avoid build warning for CONFIG_SHMEM=n

[Arnd Bergmann]

From: Arnd Bergmann <arnd@arndb.de>

The newly added 'flags' variable is unused and causes a warning if
CONFIG_SHMEM is disabled, since the shmem_acct_size() macro it is passed
into does nothing:

mm/shmem.c: In function '__shmem_file_setup':
mm/shmem.c:5816:23: error: unused variable 'flags' [-Werror=unused-variable]
 5816 |         unsigned long flags = (vm_flags & VM_NORESERVE) ? SHMEM_F_NORESERVE : 0;
      |                       ^~~~~

Replace the two macros with equivalent inline functions tto get the
argument checking.

Fixes: 6ff1610ced56 ("mm: shmem: use SHMEM_F_* flags instead of VM_* flags")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
v2: make shmem_unacct_size() inline as well.
---
 mm/shmem.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/mm/shmem.c b/mm/shmem.c
index 3f194c9842a8..b329b5302c48 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -5794,8 +5794,15 @@ EXPORT_SYMBOL_GPL(shmem_truncate_range);
 #define shmem_vm_ops				generic_file_vm_ops
 #define shmem_anon_vm_ops			generic_file_vm_ops
 #define shmem_file_operations			ramfs_file_operations
-#define shmem_acct_size(flags, size)		0
-#define shmem_unacct_size(flags, size)		do {} while (0)
+
+static inline int shmem_acct_size(unsigned long flags, loff_t size)
+{
+	return 0;
+}
+
+static inline void shmem_unacct_size(unsigned long flags, loff_t size)
+{
+}
 
 static inline struct inode *shmem_get_inode(struct mnt_idmap *idmap,
 				struct super_block *sb, struct inode *dir,
-- 
2.39.5

Re: [PATCH] [v2] mm: shmem: avoid build warning for CONFIG_SHMEM=n

[David Hildenbrand (Red Hat)]

On 12/4/25 11:28, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> The newly added 'flags' variable is unused and causes a warning if
> CONFIG_SHMEM is disabled, since the shmem_acct_size() macro it is passed
> into does nothing:
> 
> mm/shmem.c: In function '__shmem_file_setup':
> mm/shmem.c:5816:23: error: unused variable 'flags' [-Werror=unused-variable]
>   5816 |         unsigned long flags = (vm_flags & VM_NORESERVE) ? SHMEM_F_NORESERVE : 0;
>        |                       ^~~~~
> 
> Replace the two macros with equivalent inline functions tto get the
> argument checking.
> 
> Fixes: 6ff1610ced56 ("mm: shmem: use SHMEM_F_* flags instead of VM_* flags")

That's still not upstream, right?

$ git tag --contains 6ff1610ced56
mm-everything-2025-11-29-19-43
mm-everything-2025-12-03-23-49
next-20251201
next-20251203
next-20251204

So we can likely just squash it into the problematic commit before 
proceeding with it?


Thanks Arnd!

-- 
Cheers

David

Re: [PATCH] [v2] mm: shmem: avoid build warning for CONFIG_SHMEM=n

[Arnd Bergmann]

On Thu, Dec 4, 2025, at 11:34, David Hildenbrand (Red Hat) wrote:
>
> So we can likely just squash it into the problematic commit before 
> proceeding with it?

Yes, that would be best.

    Arnd

Re: [PATCH] [v2] mm: shmem: avoid build warning for CONFIG_SHMEM=n

[Mike Rapoport]

On Thu, Dec 04, 2025 at 11:34:24AM +0100, David Hildenbrand (Red Hat) wrote:
> On 12/4/25 11:28, Arnd Bergmann wrote:
> > From: Arnd Bergmann <arnd@arndb.de>
> > 
> > The newly added 'flags' variable is unused and causes a warning if
> > CONFIG_SHMEM is disabled, since the shmem_acct_size() macro it is passed
> > into does nothing:
> > 
> > mm/shmem.c: In function '__shmem_file_setup':
> > mm/shmem.c:5816:23: error: unused variable 'flags' [-Werror=unused-variable]
> >   5816 |         unsigned long flags = (vm_flags & VM_NORESERVE) ? SHMEM_F_NORESERVE : 0;
> >        |                       ^~~~~
> > 
> > Replace the two macros with equivalent inline functions tto get the
> > argument checking.
> > 
> > Fixes: 6ff1610ced56 ("mm: shmem: use SHMEM_F_* flags instead of VM_* flags")
> 
> That's still not upstream, right?
> 
> $ git tag --contains 6ff1610ced56
> mm-everything-2025-11-29-19-43
> mm-everything-2025-12-03-23-49
> next-20251201
> next-20251203
> next-20251204
> 
> So we can likely just squash it into the problematic commit before
> proceeding with it?

It's mm-nonmm-stable, I don't think fixups can go there.
 
> Thanks Arnd!
> 
> -- 
> Cheers
> 
> David

-- 
Sincerely yours,
Mike.

Re: [PATCH] [v2] mm: shmem: avoid build warning for CONFIG_SHMEM=n

[Mike Rapoport]

On Thu, Dec 04, 2025 at 11:28:59AM +0100, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> The newly added 'flags' variable is unused and causes a warning if
> CONFIG_SHMEM is disabled, since the shmem_acct_size() macro it is passed
> into does nothing:
> 
> mm/shmem.c: In function '__shmem_file_setup':
> mm/shmem.c:5816:23: error: unused variable 'flags' [-Werror=unused-variable]
>  5816 |         unsigned long flags = (vm_flags & VM_NORESERVE) ? SHMEM_F_NORESERVE : 0;
>       |                       ^~~~~
> 
> Replace the two macros with equivalent inline functions tto get the
> argument checking.
> 
> Fixes: 6ff1610ced56 ("mm: shmem: use SHMEM_F_* flags instead of VM_* flags")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>

> ---
> v2: make shmem_unacct_size() inline as well.

-- 
Sincerely yours,
Mike.

Re: [PATCH] [v2] mm: shmem: avoid build warning for CONFIG_SHMEM=n

[David Hildenbrand (Red Hat)]

On 12/4/25 11:55, Mike Rapoport wrote:
> On Thu, Dec 04, 2025 at 11:34:24AM +0100, David Hildenbrand (Red Hat) wrote:
>> On 12/4/25 11:28, Arnd Bergmann wrote:
>>> From: Arnd Bergmann <arnd@arndb.de>
>>>
>>> The newly added 'flags' variable is unused and causes a warning if
>>> CONFIG_SHMEM is disabled, since the shmem_acct_size() macro it is passed
>>> into does nothing:
>>>
>>> mm/shmem.c: In function '__shmem_file_setup':
>>> mm/shmem.c:5816:23: error: unused variable 'flags' [-Werror=unused-variable]
>>>    5816 |         unsigned long flags = (vm_flags & VM_NORESERVE) ? SHMEM_F_NORESERVE : 0;
>>>         |                       ^~~~~
>>>
>>> Replace the two macros with equivalent inline functions tto get the
>>> argument checking.
>>>
>>> Fixes: 6ff1610ced56 ("mm: shmem: use SHMEM_F_* flags instead of VM_* flags")
>>
>> That's still not upstream, right?
>>
>> $ git tag --contains 6ff1610ced56
>> mm-everything-2025-11-29-19-43
>> mm-everything-2025-12-03-23-49
>> next-20251201
>> next-20251203
>> next-20251204
>>
>> So we can likely just squash it into the problematic commit before
>> proceeding with it?
> 
> It's mm-nonmm-stable, I don't think fixups can go there.

Ah, I only looked at mm-stable and mm-unstable.

Confused why this is in nomm-stable and not mm-stable.


Anyhow:

Acked-by: David Hildenbrand (Red Hat) <david@kernel.org>

-- 
Cheers

David

Re: [PATCH] [v2] mm: shmem: avoid build warning for CONFIG_SHMEM=n

[Baolin Wang]

On 2025/12/4 18:28, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> The newly added 'flags' variable is unused and causes a warning if
> CONFIG_SHMEM is disabled, since the shmem_acct_size() macro it is passed
> into does nothing:
> 
> mm/shmem.c: In function '__shmem_file_setup':
> mm/shmem.c:5816:23: error: unused variable 'flags' [-Werror=unused-variable]
>   5816 |         unsigned long flags = (vm_flags & VM_NORESERVE) ? SHMEM_F_NORESERVE : 0;
>        |                       ^~~~~
> 
> Replace the two macros with equivalent inline functions tto get the
> argument checking.
> 
> Fixes: 6ff1610ced56 ("mm: shmem: use SHMEM_F_* flags instead of VM_* flags")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
> v2: make shmem_unacct_size() inline as well.
> ---

LGTM. Thanks.
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>

Re: [PATCH] [v2] mm: shmem: avoid build warning for CONFIG_SHMEM=n

[Pratyush Yadav]

On Thu, Dec 04 2025, Arnd Bergmann wrote:

> From: Arnd Bergmann <arnd@arndb.de>
>
> The newly added 'flags' variable is unused and causes a warning if
> CONFIG_SHMEM is disabled, since the shmem_acct_size() macro it is passed
> into does nothing:
>
> mm/shmem.c: In function '__shmem_file_setup':
> mm/shmem.c:5816:23: error: unused variable 'flags' [-Werror=unused-variable]
>  5816 |         unsigned long flags = (vm_flags & VM_NORESERVE) ? SHMEM_F_NORESERVE : 0;
>       |                       ^~~~~
>
> Replace the two macros with equivalent inline functions tto get the
> argument checking.
>
> Fixes: 6ff1610ced56 ("mm: shmem: use SHMEM_F_* flags instead of VM_* flags")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Reviewed-by: Pratyush Yadav <pratyush@kernel.org>

[...]

-- 
Regards,
Pratyush Yadav

Re: [PATCH] [v2] mm: shmem: avoid build warning for CONFIG_SHMEM=n

[Pratyush Yadav]

On Thu, Dec 04 2025, David Hildenbrand (Red Hat) wrote:

> On 12/4/25 11:55, Mike Rapoport wrote:
>> On Thu, Dec 04, 2025 at 11:34:24AM +0100, David Hildenbrand (Red Hat) wrote:
>>> On 12/4/25 11:28, Arnd Bergmann wrote:
>>>> From: Arnd Bergmann <arnd@arndb.de>
>>>>
>>>> The newly added 'flags' variable is unused and causes a warning if
>>>> CONFIG_SHMEM is disabled, since the shmem_acct_size() macro it is passed
>>>> into does nothing:
>>>>
>>>> mm/shmem.c: In function '__shmem_file_setup':
>>>> mm/shmem.c:5816:23: error: unused variable 'flags' [-Werror=unused-variable]
>>>>    5816 |         unsigned long flags = (vm_flags & VM_NORESERVE) ? SHMEM_F_NORESERVE : 0;
>>>>         |                       ^~~~~
>>>>
>>>> Replace the two macros with equivalent inline functions tto get the
>>>> argument checking.
>>>>
>>>> Fixes: 6ff1610ced56 ("mm: shmem: use SHMEM_F_* flags instead of VM_* flags")
>>>
>>> That's still not upstream, right?
>>>
>>> $ git tag --contains 6ff1610ced56
>>> mm-everything-2025-11-29-19-43
>>> mm-everything-2025-12-03-23-49
>>> next-20251201
>>> next-20251203
>>> next-20251204
>>>
>>> So we can likely just squash it into the problematic commit before
>>> proceeding with it?
>> It's mm-nonmm-stable, I don't think fixups can go there.
>
> Ah, I only looked at mm-stable and mm-unstable.
>
> Confused why this is in nomm-stable and not mm-stable.

The patch came in with the liveupdate series [0], most of which counts
as nonmm I suppose.

[0] https://lore.kernel.org/all/20251125165850.3389713-1-pasha.tatashin@soleen.com/

[...]

-- 
Regards,
Pratyush Yadav

Re: [PATCH] [v2] mm: shmem: avoid build warning for CONFIG_SHMEM=n

[Pasha Tatashin]

On Thu, Dec 4, 2025 at 5:29 AM Arnd Bergmann <arnd@kernel.org> wrote:
>
> From: Arnd Bergmann <arnd@arndb.de>
>
> The newly added 'flags' variable is unused and causes a warning if
> CONFIG_SHMEM is disabled, since the shmem_acct_size() macro it is passed
> into does nothing:
>
> mm/shmem.c: In function '__shmem_file_setup':
> mm/shmem.c:5816:23: error: unused variable 'flags' [-Werror=unused-variable]
>  5816 |         unsigned long flags = (vm_flags & VM_NORESERVE) ? SHMEM_F_NORESERVE : 0;
>       |                       ^~~~~
>
> Replace the two macros with equivalent inline functions tto get the
> argument checking.
>
> Fixes: 6ff1610ced56 ("mm: shmem: use SHMEM_F_* flags instead of VM_* flags")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
> v2: make shmem_unacct_size() inline as well.

Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com>

for v2 as well, thank you for the fixes! :-)

> ---
>  mm/shmem.c | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/mm/shmem.c b/mm/shmem.c
> index 3f194c9842a8..b329b5302c48 100644
> --- a/mm/shmem.c
> +++ b/mm/shmem.c
> @@ -5794,8 +5794,15 @@ EXPORT_SYMBOL_GPL(shmem_truncate_range);
>  #define shmem_vm_ops                           generic_file_vm_ops
>  #define shmem_anon_vm_ops                      generic_file_vm_ops
>  #define shmem_file_operations                  ramfs_file_operations
> -#define shmem_acct_size(flags, size)           0
> -#define shmem_unacct_size(flags, size)         do {} while (0)
> +
> +static inline int shmem_acct_size(unsigned long flags, loff_t size)
> +{
> +       return 0;
> +}
> +
> +static inline void shmem_unacct_size(unsigned long flags, loff_t size)
> +{
> +}
>
>  static inline struct inode *shmem_get_inode(struct mnt_idmap *idmap,
>                                 struct super_block *sb, struct inode *dir,
> --
> 2.39.5
>