Re: [PATCH v3 2/2] mm: redefine VM_* flag constants with BIT()

[Jakub Acs <acsjakub@amazon.de>]

On Wed, Oct 01, 2025 at 04:04:51PM +0200, David Hildenbrand wrote:
> >-#define VM_GROWSDOWN	0x00000100	/* general info on the segment */
> >+#define VM_GROWSDOWN	BIT(8)		/* general info on the segment */
> >  #ifdef CONFIG_MMU
> >-#define VM_UFFD_MISSING	0x00000200	/* missing pages tracking */
> >+#define VM_UFFD_MISSING	BIT(9)		/* missing pages tracking */
> >  #else /* CONFIG_MMU */
> >-#define VM_MAYOVERLAY	0x00000200	/* nommu: R/O MAP_PRIVATE mapping that might overlay a file mapping */
> >+#define VM_MAYOVERLAY	BIT(10)		/* nommu: R/O MAP_PRIVATE mapping that might overlay a file mapping */
> 
> Careful: VM_UFFD_MISSING and VM_MAYOVERLAY share the same bit,
> depending on CONFIG_MMU (9).
> 
> >  #define VM_UFFD_MISSING	0
> >  #endif /* CONFIG_MMU */
> >-#define VM_PFNMAP	0x00000400	/* Page-ranges managed without "struct page", just pure PFN */
> >-#define VM_UFFD_WP	0x00001000	/* wrprotect pages tracking */
> >+#define VM_PFNMAP	BIT(11)		/* Page-ranges managed without "struct page", just pure PFN */
> 
> -> 10

Ugh, thanks for catching these!

> 
> 11 is actually unused IIUC.
> 
> >+#define VM_UFFD_WP	BIT(12)		/* wrprotect pages tracking */
> 
> This seems to be correct again.
> 
> 
> IIRC, Andrew prefers not mixing fixes and cleanups in the same
> series if possible. So you might just want to send out patch #1
> separately and, send out patch #2 separately with a note under the
> --- that it depends on patch #1.
> 

I saw that patch #1 was applied so will leave that alone now, but took a
note for future.

For completeness adding the link to v4:
https://lore.kernel.org/all/20251002075202.11306-1-acsjakub@amazon.de/

Many Thanks,
Jakub



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