linux-kernel - Re: [PATCH V4 mm-hotfixes 1/3] mm: move page table sync declarations to linux/pgtable.h

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Message-ID: <aJm1vQ2D1YOhipos@pc636>
Date: Mon, 11 Aug 2025 11:19:57 +0200
From: Uladzislau Rezki <urezki@...il.com>
To: Mike Rapoport <rppt@...nel.org>, Harry Yoo <harry.yoo@...cle.com>
Cc: Harry Yoo <harry.yoo@...cle.com>, Dennis Zhou <dennis@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Andrey Ryabinin <ryabinin.a.a@...il.com>, x86@...nel.org,
	Borislav Petkov <bp@...en8.de>,
	Peter Zijlstra <peterz@...radead.org>,
	Andy Lutomirski <luto@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>, Tejun Heo <tj@...nel.org>,
	Uladzislau Rezki <urezki@...il.com>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	Christoph Lameter <cl@...two.org>,
	David Hildenbrand <david@...hat.com>,
	Andrey Konovalov <andreyknvl@...il.com>,
	Vincenzo Frascino <vincenzo.frascino@....com>,
	"H. Peter Anvin" <hpa@...or.com>, kasan-dev@...glegroups.com,
	Ard Biesheuvel <ardb@...nel.org>, linux-kernel@...r.kernel.org,
	Dmitry Vyukov <dvyukov@...gle.com>,
	Alexander Potapenko <glider@...gle.com>,
	Vlastimil Babka <vbabka@...e.cz>,
	Suren Baghdasaryan <surenb@...gle.com>,
	Thomas Huth <thuth@...hat.com>, John Hubbard <jhubbard@...dia.com>,
	Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
	Michal Hocko <mhocko@...e.com>,
	"Liam R. Howlett" <Liam.Howlett@...cle.com>, linux-mm@...ck.org,
	"Kirill A. Shutemov" <kas@...nel.org>,
	Oscar Salvador <osalvador@...e.de>, Jane Chu <jane.chu@...cle.com>,
	Gwan-gyeong Mun <gwan-gyeong.mun@...el.com>,
	"Aneesh Kumar K . V" <aneesh.kumar@...ux.ibm.com>,
	Joerg Roedel <joro@...tes.org>,
	Alistair Popple <apopple@...dia.com>,
	Joao Martins <joao.m.martins@...cle.com>,
	linux-arch@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH V4 mm-hotfixes 1/3] mm: move page table sync declarations
 to linux/pgtable.h

On Mon, Aug 11, 2025 at 11:05:51AM +0300, Mike Rapoport wrote:
> On Mon, Aug 11, 2025 at 02:34:18PM +0900, Harry Yoo wrote:
> > Move ARCH_PAGE_TABLE_SYNC_MASK and arch_sync_kernel_mappings() to
> > linux/pgtable.h so that they can be used outside of vmalloc and ioremap.
> > 
> > Cc: <stable@...r.kernel.org>
> > Fixes: 8d400913c231 ("x86/vmemmap: handle unpopulated sub-pmd ranges")
> > Signed-off-by: Harry Yoo <harry.yoo@...cle.com>
> > ---
> >  include/linux/pgtable.h | 16 ++++++++++++++++
> >  include/linux/vmalloc.h | 16 ----------------
> >  2 files changed, 16 insertions(+), 16 deletions(-)
> > 
> > diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
> > index 4c035637eeb7..ba699df6ef69 100644
> > --- a/include/linux/pgtable.h
> > +++ b/include/linux/pgtable.h
> > @@ -1467,6 +1467,22 @@ static inline void modify_prot_commit_ptes(struct vm_area_struct *vma, unsigned
> >  }
> >  #endif
> >  
> > +/*
> > + * Architectures can set this mask to a combination of PGTBL_P?D_MODIFIED values
> > + * and let generic vmalloc and ioremap code know when arch_sync_kernel_mappings()
> 
> If ARCH_PAGE_TABLE_SYNC_MASK can be used outside vmalloc(), the comment
> needs an update, maybe
> 
> ... and let the generic code that modifies kernel page tables
> 
> Other than that
> 
> Reviewed-by: Mike Rapoport (Microsoft) <rppt@...nel.org>
> 
> > + * needs to be called.
> > + */
> > +#ifndef ARCH_PAGE_TABLE_SYNC_MASK
> > +#define ARCH_PAGE_TABLE_SYNC_MASK 0
> > +#endif
> > +
> > +/*
> > + * There is no default implementation for arch_sync_kernel_mappings(). It is
> > + * relied upon the compiler to optimize calls out if ARCH_PAGE_TABLE_SYNC_MASK
> > + * is 0.
> > + */
> > +void arch_sync_kernel_mappings(unsigned long start, unsigned long end);
> > +
> >  #endif /* CONFIG_MMU */
> >  
> >  /*
> > diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
> > index fdc9aeb74a44..2759dac6be44 100644
> > --- a/include/linux/vmalloc.h
> > +++ b/include/linux/vmalloc.h
> > @@ -219,22 +219,6 @@ extern int remap_vmalloc_range(struct vm_area_struct *vma, void *addr,
> >  int vmap_pages_range(unsigned long addr, unsigned long end, pgprot_t prot,
> >  		     struct page **pages, unsigned int page_shift);
> >  
> > -/*
> > - * Architectures can set this mask to a combination of PGTBL_P?D_MODIFIED values
> > - * and let generic vmalloc and ioremap code know when arch_sync_kernel_mappings()
> > - * needs to be called.
> > - */
> > -#ifndef ARCH_PAGE_TABLE_SYNC_MASK
> > -#define ARCH_PAGE_TABLE_SYNC_MASK 0
> > -#endif
> > -
> > -/*
> > - * There is no default implementation for arch_sync_kernel_mappings(). It is
> > - * relied upon the compiler to optimize calls out if ARCH_PAGE_TABLE_SYNC_MASK
> > - * is 0.
> > - */
> > -void arch_sync_kernel_mappings(unsigned long start, unsigned long end);
> > -
> >  /*
> >   *	Lowlevel-APIs (not for driver use!)
> >   */
> > -- 
> > 2.43.0
> > 
> 
LGTM,

Reviewed-by: "Uladzislau Rezki (Sony)" <urezki@...il.com>

--
Uladzislau Rezki