From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lf0-f52.google.com (mail-lf0-f52.google.com [209.85.215.52]) by kanga.kvack.org (Postfix) with ESMTP id 1279582F64 for ; Thu, 5 Nov 2015 07:54:20 -0500 (EST) Received: by lfbf136 with SMTP id f136so56969218lfb.0 for ; Thu, 05 Nov 2015 04:54:19 -0800 (PST) Received: from relay.parallels.com (relay.parallels.com. [195.214.232.42]) by mx.google.com with ESMTPS id sk4si4164029lbb.74.2015.11.05.04.54.18 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 05 Nov 2015 04:54:18 -0800 (PST) Date: Thu, 5 Nov 2015 15:53:54 +0300 From: Vladimir Davydov Subject: Re: [PATCH 4/4] mm: prepare page_referenced() and page_idle to new THP refcounting Message-ID: <20151105125354.GE29259@esperanza> 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> <20151105123606.GE7614@node.shutemov.name> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20151105123606.GE7614@node.shutemov.name> Sender: owner-linux-mm@kvack.org List-ID: To: "Kirill A. Shutemov" 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 02:36:06PM +0200, Kirill A. Shutemov wrote: > 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. Out of curiosity, is it OK that __page_check_address can call pte_unmap_unlock on pte returned by huge_pte_offset, which isn't really pte, but pmd or pud? > > 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); spin_unlock(ptl); if (pte) pte_unmap(pte); would look neater IMO. Other than that, I think it's OK. At least, it looks better and less error-prone than duplicating such a huge chunk of code IMO. Thanks, Vladimir > > /* ... */ > > The helper shouldn't set pmd if the page is tracked to pte. -- 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