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Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Baolin Wang , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Usama Arif , Gregory Price , Ying Huang , Alistair Popple , Johannes Weiner , Qi Zheng , Shakeel Butt , Kairui Song , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Minchan Kim , Sergey Senozhatsky Subject: Re: [PATCH v3 01/14] mm/zsmalloc: replace PG_private with pointer comparison Message-ID: References: <20260907-remove-pg_private-v3-0-6ae22f9d9272@nvidia.com> <20260907-remove-pg_private-v3-1-6ae22f9d9272@nvidia.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260907-remove-pg_private-v3-1-6ae22f9d9272@nvidia.com> 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 > To: Sergey Senozhatsky > To: Andrew Morton > Cc: linux-mm@kvack.org > Cc: linux-kernel@vger.kernel.org > Acked-by: Johannes Weiner > Signed-off-by: Zi Yan Reviewed-by: Sergey Senozhatsky