From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wr1-f43.google.com (mail-wr1-f43.google.com [209.85.221.43]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 58C123C3BF3 for ; Thu, 7 May 2026 09:34:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.221.43 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778146477; cv=none; b=cADH3PUpAtHrPtt++xYCsWRsIZUNN6nLSxCKPcaADUUNiRHoAODojNVxomatCF1rsZeJluG+RORjWR8VjijM34lThLW7b2t26VypSHIV5Co0KDZJiZw9haX2sF6yG88YXDhmE0CrN+DfbqawFPMXICzl658OVEb7tSoWctK8Hps= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778146477; c=relaxed/simple; bh=J1bOPAWhnCUz0l1EJH+k8N+utDBA6Ynrp7a4fbyVJ+8=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=gkNkPZzeKZLU4D3PwqtZcEsUOw9nO9Hl8aLP7f6pfQ0pdoScmVO/R7Y52wuT++MQwsfRjQAACGjRFoZf7n7qcuDVvSvzcjN0dvJztNKbh5y3drJA3tcfoGxmXUEUCj5zwubwsVAg05rjaej/WO8k8USmcI05OYd2cjGcER3GMXQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=FrcAF9Dv; arc=none smtp.client-ip=209.85.221.43 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="FrcAF9Dv" Received: by mail-wr1-f43.google.com with SMTP id ffacd0b85a97d-449d6c68ed8so526441f8f.0 for ; Thu, 07 May 2026 02:34:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1778146475; x=1778751275; darn=vger.kernel.org; h=user-agent:in-reply-to:content-disposition:mime-version:references :reply-to:message-id:subject:cc:to:from:date:from:to:cc:subject:date :message-id:reply-to; bh=702H2S4N5D7RzWa0xl6b2kbo8YfTndWwy7+YUwKRtHE=; b=FrcAF9DvhyCapZkzDiazXauToyLnGDhr95SgYtBd0oQrX3lq3d0k52jCLf9Tzq/0rI AMVeQBr9BI/GHu8o+DY/jNdEUVoCtztBOLvDCF3fLIG9LLhNuufv2ytz8cjb+GqqfZVw UyOmIwYychdti6YtYrGdFGFKxD/GUPs3DlLzbTvE9f64V3HPpY8XwnQ8dwRhJ7c/13L7 ZXSr0uooUnz6aY84N6+7lcTMUGTJpCXG0Y6UtozhV8r3UtOxGfiXNXaxK5aeQKC+0UQX 1tU85Y5H8GqIgPSvWsWDx+1VCgsM7CPr5O2vmqMGQNHNVoiwXeLggZsMNMxd2Xq/hWhH M+zg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1778146475; x=1778751275; h=user-agent:in-reply-to:content-disposition:mime-version:references :reply-to:message-id:subject:cc:to:from:date:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=702H2S4N5D7RzWa0xl6b2kbo8YfTndWwy7+YUwKRtHE=; b=S2vWLaXl4ufwuDBy6WHosUtj4y7H6KaKLIQd+nCn7gaTfW3NwAEGmMS9GhiEvopmOy BMPH8K/6i+SC8Ox2AWF5aAv5rD1fknSRdECpLqs5ICxPpOu/WN0YByzGIE7sYnTRgPrY QRGUULghhKvU+Xt3rTI1bY/Docp7T/ovWmAgW6PWyLfLQMVIXKj+DpFY+cKEiTehvmY3 5kJrZMdURrwK4m+6YlgSHq2N60ZucIiGCFIKHkw6Ahtdr2SzqnwzBkt5tcsfpxKgJsZ5 UYwQKP8IrBcF7fHGJ4WfE8JW278SfjrNCDlj6HQhqqQUonPqW/vkihnMBdoFWIv18ouQ a3/Q== X-Forwarded-Encrypted: i=1; AFNElJ8H1MpImd01QAPu8byLmWMjOpPSD9gajeyQn/vzovwYoKyHepTuO6Puvjffsf8Fcv4ScUAEWcoKFHuM@vger.kernel.org X-Gm-Message-State: AOJu0Yz0EGgAYeGtH6cu9vpbfycFqdrXm1h9eYzbj+Q6zlbudRemmvXc TClJPInQ0TWSWhSA8C/7QT2fWjU+9sF1u9W3so+X9EZphsPug8J3fZVZ X-Gm-Gg: AeBDiesBboMNl97JVdvzKtNrPuC2XrtmTAN2prJRoJXzE7W80nBNxuxbDQVodkwEBCo JwniHTRJRk4/wBhfoT4909609gWBc7xR58Aoiieqs36PHQtiPDKg5AG++QnTrXFQHZPG2VvJwJU NJBPXvZY/UVo+waxphHlcd9i0+zC7G2wwW8A0GX/qgGVp1s9mTxq6pOB/JtTv/ejXoQ99tos9a5 GCMiy6KHDzRVzhX01okKk2IiHG/QNLlG1TLaCoxsxgZoE2Y4/wn/1C5E9Td8J6Sb7UBWgZqgIfP PJojXRAUXH4PqoJU2yP2odPkGpEm2qEknbMt/WHTjybqjDuLXPMRakfH75O3dXCgXr/EnZyFstK 3pQuN9s0YPNrZzW7Bl9/K2SZdX0pyjWWIFRQRSPCxb76MCf1LcsaHru/p+i7u4YtcbFS81AkeNs 6utVGNRdGBCVqGQiCOXyeJhYinJ0otkfdiPbeeuop8VN8= X-Received: by 2002:a05:6000:420b:b0:43b:5097:6f62 with SMTP id ffacd0b85a97d-4515d99f016mr11855726f8f.36.1778146474525; Thu, 07 May 2026 02:34:34 -0700 (PDT) Received: from localhost ([185.92.221.13]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-45054b03e04sm18747199f8f.21.2026.05.07.02.34.33 (version=TLS1_2 cipher=ECDHE-ECDSA-CHACHA20-POLY1305 bits=256/256); 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-s390@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