mm, vc_screen: move __free() handler that frees a page to a common header

[PATCH] mm, vc_screen: move __free() handler that frees a page to a common header

Posted by Mike Rapoport 3 months, 2 weeks ago

From: "Mike Rapoport (Microsoft)" <rppt@kernel.org>

vc_screen defines __free() handler that frees a page using free_page().
Move that definition to include/linux/gfp.h next to free_page() and
rename it from free_page_ptr to free_page.

Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
---
 drivers/tty/vt/vc_screen.c | 6 ++----
 include/linux/gfp.h        | 2 ++
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/tty/vt/vc_screen.c b/drivers/tty/vt/vc_screen.c
index c814644ef4ee..d2029f029de6 100644
--- a/drivers/tty/vt/vc_screen.c
+++ b/drivers/tty/vt/vc_screen.c
@@ -53,8 +53,6 @@
 #define HEADER_SIZE	4u
 #define CON_BUF_SIZE (IS_ENABLED(CONFIG_BASE_SMALL) ? 256 : PAGE_SIZE)
 
-DEFINE_FREE(free_page_ptr, void *, if (_T) free_page((unsigned long)_T));
-
 /*
  * Our minor space:
  *
@@ -371,7 +369,7 @@ vcs_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
 	loff_t pos;
 	bool viewed, attr, uni_mode;
 
-	char *con_buf __free(free_page_ptr) = (char *)__get_free_page(GFP_KERNEL);
+	char *con_buf __free(free_page) = (char *)__get_free_page(GFP_KERNEL);
 	if (!con_buf)
 		return -ENOMEM;
 
@@ -596,7 +594,7 @@ vcs_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
 	if (use_unicode(inode))
 		return -EOPNOTSUPP;
 
-	char *con_buf __free(free_page_ptr) = (char *)__get_free_page(GFP_KERNEL);
+	char *con_buf __free(free_page) = (char *)__get_free_page(GFP_KERNEL);
 	if (!con_buf)
 		return -ENOMEM;
 
diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index 0ceb4e09306c..93a6a532f10d 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -385,6 +385,8 @@ extern void free_pages(unsigned long addr, unsigned int order);
 #define __free_page(page) __free_pages((page), 0)
 #define free_page(addr) free_pages((addr), 0)
 
+DEFINE_FREE(free_page, unsigned long, if (_T) free_page(_T));
+
 void page_alloc_init_cpuhp(void);
 int decay_pcp_high(struct zone *zone, struct per_cpu_pages *pcp);
 void drain_zone_pages(struct zone *zone, struct per_cpu_pages *pcp);

base-commit: 211ddde0823f1442e4ad052a2f30f050145ccada
-- 
2.50.1

Re: [PATCH] mm, vc_screen: move __free() handler that frees a page to a common header

Posted by Greg Kroah-Hartman 3 months, 2 weeks ago

On Mon, Oct 20, 2025 at 05:30:55PM +0300, Mike Rapoport wrote:
> From: "Mike Rapoport (Microsoft)" <rppt@kernel.org>
> 
> vc_screen defines __free() handler that frees a page using free_page().
> Move that definition to include/linux/gfp.h next to free_page() and
> rename it from free_page_ptr to free_page.
> 
> Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
> ---
>  drivers/tty/vt/vc_screen.c | 6 ++----
>  include/linux/gfp.h        | 2 ++
>  2 files changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/tty/vt/vc_screen.c b/drivers/tty/vt/vc_screen.c
> index c814644ef4ee..d2029f029de6 100644
> --- a/drivers/tty/vt/vc_screen.c
> +++ b/drivers/tty/vt/vc_screen.c
> @@ -53,8 +53,6 @@
>  #define HEADER_SIZE	4u
>  #define CON_BUF_SIZE (IS_ENABLED(CONFIG_BASE_SMALL) ? 256 : PAGE_SIZE)
>  
> -DEFINE_FREE(free_page_ptr, void *, if (_T) free_page((unsigned long)_T));
> -
>  /*
>   * Our minor space:
>   *
> @@ -371,7 +369,7 @@ vcs_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
>  	loff_t pos;
>  	bool viewed, attr, uni_mode;
>  
> -	char *con_buf __free(free_page_ptr) = (char *)__get_free_page(GFP_KERNEL);
> +	char *con_buf __free(free_page) = (char *)__get_free_page(GFP_KERNEL);

As per the other thread recently, why can't we just use kmalloc() here
instead?

thanks,

greg k-h

Re: [PATCH] mm, vc_screen: move __free() handler that frees a page to a common header

Posted by Matthew Wilcox 3 months, 2 weeks ago

On Mon, Oct 20, 2025 at 05:30:55PM +0300, Mike Rapoport wrote:
> From: "Mike Rapoport (Microsoft)" <rppt@kernel.org>
> 
> vc_screen defines __free() handler that frees a page using free_page().
> Move that definition to include/linux/gfp.h next to free_page() and
> rename it from free_page_ptr to free_page.

I don't think this is a good idea.  This is a bad interface and we
should be moving people away from it, not making it easier to use.