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Howlett" , Vlastimil Babka , Suren Baghdasaryan , Michal Hocko , Qi Zheng , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH v3 6/6] mm/mm_init: add zone mismatch warning during page init Message-ID: References: <20260929053231.66085-1-songmuchun@bytedance.com> <20260929053231.66085-7-songmuchun@bytedance.com> <78D5D6AA-BE36-432C-B0F7-453F93DF18C0@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <78D5D6AA-BE36-432C-B0F7-453F93DF18C0@linux.dev> X-Stat-Signature: hmix88xhjo5d1irjry3tp9pighsdo844 X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 2820940008 X-HE-Tag: 1790929385-645466 X-HE-Meta: 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 yxfn3Ckf 87olOFO7eHhMV+RtjR4apCkZvp5w/kxoGHhYultuMdy6YNDgjMsc8V00DaJ3Hfa+RTD2Eog8BGHOlIxr8FDf2fGY+001evUDlgHg0wO1bxVs8Lp7zttpf+9xZzK3KS/L88cOZOx+nvPwrs0hnvxWN22XoQmBkQ+xxTEcmxe428w/9Q9A8Wo8Rv2zHLRhuxKX5+bwcdOBMuogPM/bh0jFgr2tHs1MNS3D8n5xP9zo9Ok0XAImrefEQ8em0PPnXGD2s+/Rw2mlFA1nC1yz8odgXok5jClxk1MHr4OyU6vRYYjloEDRkKdnYy2zj9nprxYYkFYhSi/Gy+ljnIK5OIbI8ISRvYd/ElaCrQpray8Gy6wgzUtjvzBCBk3D3CyBOuzC4yTwbHQaE6kLIzYGLIuDw0UdJxkU9us4shL2bvhRxpGTg0jGrBvCJCsp8lKaGNu+wWJeT Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Oct 02, 2026 at 09:48:42AM +0800, Muchun Song wrote: > > > > On Oct 1, 2026, at 22:42, Mike Rapoport wrote: > > > > Hi Muchun, > > Hi, > > > > > On Tue, Sep 29, 2026 at 01:32:31PM +0800, Muchun Song wrote: > >> For vmemmap-optimized sections, tail struct pages may be backed by > >> shared vmemmap pages. Those shared pages must carry the same page zone > >> ID as the struct pages initialized for the section. > >> > >> Warn in __init_single_page() if the shared tail page has a different > >> page_zone_id(), which would indicate inconsistent initialization. > >> > >> Signed-off-by: Muchun Song > >> Acked-by: Qi Zheng > >> --- > >> v3: > >> - Collect Acked-by from Qi Zheng > >> > >> v2: > >> - New patch. > >> --- > >> mm/mm_init.c | 3 +++ > >> 1 file changed, 3 insertions(+) > >> > >> diff --git a/mm/mm_init.c b/mm/mm_init.c > >> index 1650d6bc1211..bd02e8d06965 100644 > >> --- a/mm/mm_init.c > >> +++ b/mm/mm_init.c > >> @@ -609,6 +609,9 @@ void __meminit __init_single_page(struct page *page, unsigned long pfn, > >> if (!is_highmem_idx(zone)) > >> set_page_address(page, __va(pfn << PAGE_SHIFT)); > >> #endif > >> + VM_WARN_ON_ONCE(vmemmap_optimizable_order(pfn_to_section_compound_order(pfn)) && > >> + page_zone_id(page + VMEMMAP_OPTIMIZATION_NR_STRUCT_PAGES) != > >> + page_zone_id(page)); > > > > Hmm, page + VMEMMAP_OPTIMIZATION_NR_STRUCT_PAGES is initialized a tad later > > than page so it'll have stale data in the page->flags, won't it? > > Lance is right. The shared tail struct pages are already initialized by > vmemmap_shared_tail_page() during vmemmap population, so they're not stale. > The head 64 struct pages are initialized later — right here, after vmemmap > population. Still it looks out of place here, can this check be done in sparse-vmemmap somehow? > Thanks, > Muchun > > > > >> } > >> > >> #ifdef CONFIG_NUMA > >> -- > >> 2.54.0 > >> > > > > -- > > Sincerely yours, > > Mike. > > -- Sincerely yours, Mike.