From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f50.google.com (mail-wm0-f50.google.com [74.125.82.50]) by kanga.kvack.org (Postfix) with ESMTP id 1166082F64 for ; Thu, 5 Nov 2015 07:36:10 -0500 (EST) Received: by wmll128 with SMTP id l128so12260137wml.0 for ; Thu, 05 Nov 2015 04:36:09 -0800 (PST) Received: from mail-wi0-x232.google.com (mail-wi0-x232.google.com. [2a00:1450:400c:c05::232]) by mx.google.com with ESMTPS id n127si10980540wmd.24.2015.11.05.04.36.08 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 05 Nov 2015 04:36:08 -0800 (PST) Received: by wijp11 with SMTP id p11so9551157wij.0 for ; Thu, 05 Nov 2015 04:36:08 -0800 (PST) Date: Thu, 5 Nov 2015 14:36:06 +0200 From: "Kirill A. Shutemov" Subject: Re: [PATCH 4/4] mm: prepare page_referenced() and page_idle to new THP refcounting Message-ID: <20151105123606.GE7614@node.shutemov.name> References: <1446564375-72143-1-git-send-email-kirill.shutemov@linux.intel.com> <1446564375-72143-5-git-send-email-kirill.shutemov@linux.intel.com> <20151105091013.GC29259@esperanza> <20151105092459.GC7614@node.shutemov.name> <20151105120726.GD29259@esperanza> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20151105120726.GD29259@esperanza> Sender: owner-linux-mm@kvack.org List-ID: To: Vladimir Davydov Cc: "Kirill A. Shutemov" , Andrew Morton , Andrea Arcangeli , Hugh Dickins , Naoya Horiguchi , Sasha Levin , Minchan Kim , linux-kernel@vger.kernel.org, linux-mm@kvack.org On Thu, Nov 05, 2015 at 03:07:26PM +0300, Vladimir Davydov wrote: > @@ -849,30 +836,23 @@ static int page_referenced_one(struct page *page, struct vm_area_struct *vma, > if (pmd_page(*pmd) != page) > goto unlock_pmd; > > - if (vma->vm_flags & VM_LOCKED) { > - pra->vm_flags |= VM_LOCKED; > - ret = SWAP_FAIL; /* To break the loop */ > - goto unlock_pmd; > - } > - > - if (pmdp_clear_flush_young_notify(vma, address, pmd)) > - referenced++; > - spin_unlock(ptl); > + pte = (pte_t *)pmd; pmd_t and pte_t are not always compatible. We shouldn't pretend they are. And we shouldn't use pte_unmap_unlock() to unlock pmd table. What about interface like this (I'm not sure about helper's name): void page_check_address_transhuge(struct page *page, struct mm_struct *mm, unsigned long address, pmd_t **pmdp, pte_t **ptep, spinlock_t **ptlp); page_check_address_transhuge(page, mm, address, &pmd, &pte, &ptl); if (pmd) { /* handle pmd... */ } else if (pte) { /* handle pte... */ } else { return SWAP_AGAIN; } /* common stuff */ if (pmd) spin_unlock(ptl); else pte_unmap_unlock(pte, ptl); /* ... */ The helper shouldn't set pmd if the page is tracked to pte. -- Kirill A. Shutemov -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org