Subject: Re: linux-next: manual merge of the kvm tree with the vfs-brauner tree

From: Stephen Rothwell <[email-masked]>
Date: Mon, 4 Dec 2023 11:51:48 +1100

Hi all,

On Wed, 22 Nov 2023 12:55:39 +1100 Stephen Rothwell <[email-masked]> wrote:
>
> Today's linux-next merge of the kvm tree got a conflict in:
> 
>   include/linux/pagemap.h
> 
> between commit:
> 
>   762321dab9a7 ("filemap: add a per-mapping stable writes flag")

This is now in Linus' tree.

> from the vfs-brauner tree and commit:
> 
>   0003e2a41468 ("mm: Add AS_UNMOVABLE to mark mapping as completely unmovable")
> 
> from the kvm tree.
> 
> I fixed it up (see below) and can carry the fix as necessary. This
> is now fixed as far as linux-next is concerned, but any non trivial
> conflicts should be mentioned to your upstream maintainer when your tree
> is submitted for merging.  You may also want to consider cooperating
> with the maintainer of the conflicting tree to minimise any particularly
> complex conflicts.

The current resolution is below.

-- 
Cheers,
Stephen Rothwell

diff --cc include/linux/pagemap.h
index 06142ff7f9ce,bf2965b01b35..c2d90588c0bf
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@@ -203,9 -203,8 +203,10 @@@ enum mapping_flags 
  	/* writeback related tags are not used */
  	AS_NO_WRITEBACK_TAGS = 5,
  	AS_LARGE_FOLIO_SUPPORT = 6,
 -	AS_RELEASE_ALWAYS = 7,	/* Call ->release_folio(), even if no private data */
 -	AS_UNMOVABLE	= 8,	/* The mapping cannot be moved, ever */
 +	AS_RELEASE_ALWAYS,	/* Call ->release_folio(), even if no private data */
 +	AS_STABLE_WRITES,	/* must wait for writeback before modifying
 +				   folio contents */
++	AS_UNMOVABLE,		/* The mapping cannot be moved, ever */
  };
  
  /**
@@@ -291,21 -290,22 +292,37 @@@ static inline void mapping_clear_releas
  	clear_bit(AS_RELEASE_ALWAYS, &mapping->flags);
  }
  
+ static inline void mapping_set_unmovable(struct address_space *mapping)
+ {
+ 	/*
+ 	 * It's expected unmovable mappings are also unevictable. Compaction
+ 	 * migrate scanner (isolate_migratepages_block()) relies on this to
+ 	 * reduce page locking.
+ 	 */
+ 	set_bit(AS_UNEVICTABLE, &mapping->flags);
+ 	set_bit(AS_UNMOVABLE, &mapping->flags);
+ }
+ 
+ static inline bool mapping_unmovable(struct address_space *mapping)
+ {
+ 	return test_bit(AS_UNMOVABLE, &mapping->flags);
+ }
+ 
 +static inline bool mapping_stable_writes(const struct address_space *mapping)
 +{
 +	return test_bit(AS_STABLE_WRITES, &mapping->flags);
 +}
 +
 +static inline void mapping_set_stable_writes(struct address_space *mapping)
 +{
 +	set_bit(AS_STABLE_WRITES, &mapping->flags);
 +}
 +
 +static inline void mapping_clear_stable_writes(struct address_space *mapping)
 +{
 +	clear_bit(AS_STABLE_WRITES, &mapping->flags);
 +}
 +
  static inline gfp_t mapping_gfp_mask(struct address_space * mapping)
  {
  	return mapping->gfp_mask;