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b=F55OsVzbB+sqFBKP7J+BrH1GvFPebPOdbR2Xge/GQqrDhiq6nT70vQBscS1ZeIMds OedYpOxhrTriQ6Tjk7mkgfoCInabP2ZllSulKNe+yA3uTlHp61tqzBjp/aadhkwyyX J1/wIuso3mvLmLHBEwRC7IwIo/89O/EqeNGzUnKZxQHeEDUUqy9SFEDIuHahiTIuSD qAPyRTQgC/4jaAbr3H7z6jRj/qMPq74wdf7QngCRn32RJhLSiGrQTt1942aMoBCWAj 4iTQT+0UwzHKLgw2n8z8ksTOBU6RH9RiJCID2DipMbOv96pYXwm0yBL2l15LnO4tht 889wlCgfQX9ew== Date: Mon, 1 Jun 2026 13:15:29 +0100 From: Lorenzo Stoakes To: Alexander Gordeev Cc: Andrew Morton , David Hildenbrand , Anshuman Khandual , Oscar Salvador , Wei Yang , linux-s390@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3] mm/page_vma_mapped_walk: Use ptep_get_lockless() for lockless access Message-ID: References: <20260528075507.1821939-1-agordeev@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260528075507.1821939-1-agordeev@linux.ibm.com> X-Stat-Signature: 6prfnndiwui836fx6det3a564aujet6t X-Rspamd-Queue-Id: 5EA564000D X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1780316134-909863 X-HE-Meta: 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 oJQcW+dG P9DhgHL0c7IP33jVOgdOKCm7isUFRN2HFGfxm5HN1bBDAMGYaBPIAm7IUj9apMQ9FPD1gxeLILBjGerdiCojQbJKddwpgZKdSawqYRPfyUYGnbcmPg6NQ5WFrISQ+IVYT58gcqmlJGRC6oQqJtOMlX21XQnc2bw7tIb85Ndrvpkwk2hbHXYGHnJYsCQHRdV9myZjQGFjqca6qMfHDYLWXqsFC/liKsj3RYLQIlGySkCOUrnuryVD0bnQYTdrVJoW1UVmXSkx0x0Dt2ESYBq6Q3CGWUkYxtqt2FJf+eLfrIpbICN5XPTyqk1UBjQL44LnKMoroCUhHWHOGRrfCSyF41hWm8HRxDkQPI+JyUaghi6Ha6eE0x5lo7ADVZW7besOLLxQTg4vPcttgtssxp0Q1xS/AYg6Yu2A+Vyg8 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, May 28, 2026 at 09:55:07AM +0200, Alexander Gordeev wrote: > Switch from ptep_get() to ptep_get_lockless() accessor for > PTE reads when no lock is taken. > > Signed-off-by: Alexander Gordeev Oh and the logic looks good so with the commit message updated, feel free to add: Reviewed-by: Lorenzo Stoakes > --- > mm/page_vma_mapped.c | 9 +++++++-- > 1 file changed, 7 insertions(+), 2 deletions(-) > > diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c > index a4d52fdb3056..2ccbabfb2cc1 100644 > --- a/mm/page_vma_mapped.c > +++ b/mm/page_vma_mapped.c > @@ -41,7 +41,7 @@ static bool map_pte(struct page_vma_mapped_walk *pvmw, pmd_t *pmdvalp, > if (!pvmw->pte) > return false; > > - ptent = ptep_get(pvmw->pte); > + ptent = ptep_get_lockless(pvmw->pte); > > if (pte_none(ptent)) { > return false; > @@ -183,6 +183,7 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw) > struct mm_struct *mm = vma->vm_mm; > unsigned long end; > spinlock_t *ptl; > + pte_t pteval; > pgd_t *pgd; > p4d_t *p4d; > pud_t *pud; > @@ -310,7 +311,11 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw) > goto restart; > } > pvmw->pte++; > - } while (pte_none(ptep_get(pvmw->pte))); > + if (!pvmw->ptl) > + pteval = ptep_get_lockless(pvmw->pte); > + else > + pteval = ptep_get(pvmw->pte); > + } while (pte_none(pteval)); > > if (!pvmw->ptl) { > spin_lock(ptl); > -- > 2.51.0 >