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Thu, 07 May 2026 02:34:33 -0700 (PDT) Date: Thu, 7 May 2026 09:34:33 +0000 From: Wei Yang To: Alexander Gordeev Cc: Andrew Morton , David Hildenbrand , Lorenzo Stoakes , Anshuman Khandual , Oscar Salvador , linux-s390@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Gerald Schaefer , Heiko Carstens , Vasily Gorbik Subject: Re: [PATCH v2] mm/page_vma_mapped_walk: Use ptep_get_lockless() for lockless access Message-ID: <20260507093433.q5xybwumryxclnqy@master> Reply-To: Wei Yang References: <20260504130434.2285053-1-agordeev@linux.ibm.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: <20260504130434.2285053-1-agordeev@linux.ibm.com> User-Agent: NeoMutt/20170113 (1.7.2) On Mon, May 04, 2026 at 03:04:34PM +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 >--- > mm/page_vma_mapped.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > >diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c >index a4d52fdb3056..6559e17f11c2 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; >@@ -310,7 +310,7 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw) > goto restart; > } > pvmw->pte++; >- } while (pte_none(ptep_get(pvmw->pte))); >+ } while (pte_none(ptep_get_lockless(pvmw->pte))); As Oscar mentioned in lkml.org/lkml/2026/4/27/630, map_pte() may take the lock. So probably it is not right? > > if (!pvmw->ptl) { > spin_lock(ptl); >-- >2.51.0 > -- Wei Yang Help you, Help me