From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0CB1CC433FE for ; Tue, 1 Nov 2022 18:31:28 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 7B0D56B0071; Tue, 1 Nov 2022 14:31:27 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 760EC6B0073; Tue, 1 Nov 2022 14:31:27 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 64F6F6B0074; Tue, 1 Nov 2022 14:31:27 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 5594D6B0071 for ; Tue, 1 Nov 2022 14:31:27 -0400 (EDT) Received: from smtpin14.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id C05A2A0E9A for ; Tue, 1 Nov 2022 18:31:26 +0000 (UTC) X-FDA: 80085716172.14.85C53C7 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf02.hostedemail.com (Postfix) with ESMTP id 474E280054 for ; Tue, 1 Nov 2022 18:31:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=qBLHlADSVQYJJAga91iK1vdxN6g7v8WADT/OUBV0m2g=; b=P7B1fXOBgO5orKrJzyAqbLXIWM Y3WxBfOUknWBjVH+BTs4EVlsA/evht7/yQD58hs0nkXI8buVJycbOPp98xA7ksc2bie+XT5CYPSaJ I91PNt5SN1Pk3Dt/fPTREPNTcInb4T2WAuS1BKvpTUBhhn9YKa9ZCZ+gxm6STPBzQFuElnLgSyVij 3tKq0aREX7WIT+iilF9dtzB+IZoH4t4n1HY9jf7JQLuFHVHy/oCJvhN1+wXRBZQ/93ve1HhfBCAgx xa6s8zrc4XpoFWcDFJbYIV8YLFQv2fFNm3VT8mI8bNHJDuC3nRc5IiUJn9qShKyEhJZGCJ7dU/chR xwT9FJwg==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1opw2o-004pvT-Ez; Tue, 01 Nov 2022 18:31:26 +0000 Date: Tue, 1 Nov 2022 18:31:26 +0000 From: Matthew Wilcox To: "Vishal Moola (Oracle)" Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, akpm@linux-foundation.org, Hugh Dickins , Peter Xu Subject: Re: [PATCH 3/5] userfualtfd: Replace lru_cache functions with folio_add functions Message-ID: References: <20221101175326.13265-1-vishal.moola@gmail.com> <20221101175326.13265-4-vishal.moola@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221101175326.13265-4-vishal.moola@gmail.com> ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1667327486; a=rsa-sha256; cv=none; b=ddEIMxjLUlwgapbzGrqB1ASl1nThIoRmjnFoMAzzhTdwUf9m2B0iu9gQFOG9LETu+aUJmi nXfLU4PkbQ7kSvbPVy7LqkrSkH/w9ji6++rimpntQ7qqERq/aZSUj2nssGV33y+Cwyxk1o pX6lqeB3c+bc3Psx1plQNLy7cp2rOkI= ARC-Authentication-Results: i=1; imf02.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=P7B1fXOB; dmarc=none; spf=none (imf02.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1667327486; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=qBLHlADSVQYJJAga91iK1vdxN6g7v8WADT/OUBV0m2g=; b=RlzACyEEOvY2mE/hkXL0w9yYjXH/mrUiQxxvXK/lQILAgt56zxSeFMGx4tWzm8Vwe1ajQ9 de8G1LrZHzkEv0hJJ9wA5uPdcZlAs/FkqSvNRKcB49VrfzVQpu23Rg4xxgoFb9Y3OLZVlf MKXpNrMSa/LRJTWfmkg247/hJmrJXhs= X-Stat-Signature: ybw5zwhzw4up6heqyoifi1huo1yd41ds X-Rspamd-Queue-Id: 474E280054 Authentication-Results: imf02.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=P7B1fXOB; dmarc=none; spf=none (imf02.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org X-Rspam-User: X-Rspamd-Server: rspam07 X-HE-Tag: 1667327485-473062 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Nov 01, 2022 at 10:53:24AM -0700, Vishal Moola (Oracle) wrote: > Replaces lru_cache_add() and lru_cache_add_inactive_or_unevictable() > with folio_add_lru() and folio_add_lru_vma(). This is in preparation for > the removal of lru_cache_add(). Ummmmm. Reviewing this patch reveals a bug (not introduced by your patch). Look: mfill_atomic_install_pte: bool page_in_cache = page->mapping; mcontinue_atomic_pte: ret = shmem_get_folio(inode, pgoff, &folio, SGP_NOALLOC); ... page = folio_file_page(folio, pgoff); ret = mfill_atomic_install_pte(dst_mm, dst_pmd, dst_vma, dst_addr, page, false, wp_copy); That says pretty plainly that mfill_atomic_install_pte() can be passed a tail page from shmem, and if it is ... if (page_in_cache) { ... } else { page_add_new_anon_rmap(page, dst_vma, dst_addr); lru_cache_add_inactive_or_unevictable(page, dst_vma); } it'll get put on the rmap as an anon page! > Signed-off-by: Vishal Moola (Oracle) > --- > mm/userfaultfd.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c > index e24e8a47ce8a..2560973b00d8 100644 > --- a/mm/userfaultfd.c > +++ b/mm/userfaultfd.c > @@ -66,6 +66,7 @@ int mfill_atomic_install_pte(struct mm_struct *dst_mm, pmd_t *dst_pmd, > bool vm_shared = dst_vma->vm_flags & VM_SHARED; > bool page_in_cache = page->mapping; > spinlock_t *ptl; > + struct folio *folio; > struct inode *inode; > pgoff_t offset, max_off; > > @@ -113,14 +114,15 @@ int mfill_atomic_install_pte(struct mm_struct *dst_mm, pmd_t *dst_pmd, > if (!pte_none_mostly(*dst_pte)) > goto out_unlock; > > + folio = page_folio(page); > if (page_in_cache) { > /* Usually, cache pages are already added to LRU */ > if (newly_allocated) > - lru_cache_add(page); > + folio_add_lru(folio); > page_add_file_rmap(page, dst_vma, false); > } else { > page_add_new_anon_rmap(page, dst_vma, dst_addr); > - lru_cache_add_inactive_or_unevictable(page, dst_vma); > + folio_add_lru_vma(folio, dst_vma); > } > > /* > -- > 2.38.1 > >