linux-kernel - Re: [PATCH] mm: move mask update out of the atomic context

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Message-ID: <aFkgTA+02bV6nldk@li-008a6a4c-3549-11b2-a85c-c5cc2836eea2.ibm.com>
Date: Mon, 23 Jun 2025 11:37:16 +0200
From: Alexander Gordeev <agordeev@...ux.ibm.com>
To: Dev Jain <dev.jain@....com>
Cc: Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm: move mask update out of the atomic context

On Mon, Jun 23, 2025 at 02:26:29PM +0530, Dev Jain wrote:
> 
> On 23/06/25 1:34 pm, Alexander Gordeev wrote:
> > There is not need to modify page table synchronization mask
> > while apply_to_pte_range() holds user page tables spinlock.
> 
> I don't get you, what is the problem with the current code?
> Are you just concerned about the duration of holding the
> lock?

Yes.

> > Signed-off-by: Alexander Gordeev <agordeev@...ux.ibm.com>
> > ---
> >   mm/memory.c | 3 ++-
> >   1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > diff --git a/mm/memory.c b/mm/memory.c
> > index 8eba595056fe..6849ab4e44bf 100644
> > --- a/mm/memory.c
> > +++ b/mm/memory.c
> > @@ -3035,12 +3035,13 @@ static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
> >   			}
> >   		} while (pte++, addr += PAGE_SIZE, addr != end);
> >   	}
> > -	*mask |= PGTBL_PTE_MODIFIED;
> >   	arch_leave_lazy_mmu_mode();
> >   	if (mm != &init_mm)
> >   		pte_unmap_unlock(mapped_pte, ptl);
> > +	*mask |= PGTBL_PTE_MODIFIED;
> > +
> >   	return err;
> >   }