Re: [PATCH v3 01/14] mm/zsmalloc: replace PG_private with pointer comparison

[Sergey Senozhatsky]

On (26/09/07 22:56), Zi Yan wrote:
> zsmalloc uses PG_private to indicate first zpdesc in a zspage chain. It is
> equivalent to check zpdesc == zspage->first_zpdesc. Replace
> is_first_zpdesc() with zpdesc == zspage->first_zpdesc in obj_allocated().
> 
> For get_first_zpdesc(), first_zpdesc is from zspage->first_zpdesc, so
> replace is_first_zpdesc() with first_zpdesc->zspage == zspage, the second
> requirement of a zspage chain, where all zpdescs point to the same zspage.
> 
> is_first_zpdesc(), is only used in VM_BUG_ON_PAGE(), so performance impact
> should be negligible. While at it, change VM_BUG_ON() to
> VM_WARN_ON_ONCE_PAGE().
> 
> It prepares for a future commit that remove PG_private.
> 
> No functional change intended.
> 
> Assisted-by: Claude:claude-opus-4-8
> Assisted-by: Codex:gpt-5
> To: Minchan Kim <minchan@xxxxxxxxxx>
> To: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>
> To: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: linux-mm@xxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>
> Signed-off-by: Zi Yan <ziy@xxxxxxxxxx>

Reviewed-by: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>