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]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id DD1E6E9A047 for ; Wed, 18 Feb 2026 11:01:56 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 4A8916B0093; Wed, 18 Feb 2026 06:01:56 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 480936B0095; Wed, 18 Feb 2026 06:01:56 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 397926B0096; Wed, 18 Feb 2026 06:01:56 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 21C116B0093 for ; Wed, 18 Feb 2026 06:01:56 -0500 (EST) Received: from smtpin24.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id CB15313AF79 for ; Wed, 18 Feb 2026 11:01:55 +0000 (UTC) X-FDA: 84457287390.24.7A15C27 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf24.hostedemail.com (Postfix) with ESMTP id 16645180006 for ; Wed, 18 Feb 2026 11:01:53 +0000 (UTC) Authentication-Results: imf24.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b="d/+TltNQ"; spf=pass (imf24.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1771412514; 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-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=iMbPZHjKcPTwi/7rkNe+hbCwdLCa16i3c+99UW8vyOg=; b=UFMVKvTGGyBOqBUm3xAhBmVFOWUUhl4rTXz78wOIZskb9D/OKIph18uoyHFY4gFlKKQ7oD 8M+XC2C+Y3Fv4htlxIA4kRQzWSb44L1PnL9p/KCgn3kMpFpc4oJd1KCcQQOWqyv64f+8up aeERaKTUWbHd1ss8armefsBS5CLKDuw= ARC-Authentication-Results: i=1; imf24.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b="d/+TltNQ"; spf=pass (imf24.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1771412514; a=rsa-sha256; cv=none; b=pP3TvpwEd1A//2KbNhed1Vpa1G5CDZtzF3+Wu9y4j94nyEn79780pQuIK4xpCP8CMFNZX6 2iEAtYXRit9bSXho5BOf4SUURx/hfeNZvnpgxpBHIhPHV5yQiPjUDOCcZAmSu/iNuAFuef LFT2qZLmuPXUi04oqjqBcesoKnu1rRo= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id DED8341934; Wed, 18 Feb 2026 11:01:52 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E813BC19421; Wed, 18 Feb 2026 11:01:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1771412512; bh=1bht8Tpqraf9dvK6mi+HcVvYMPfVmAZiLHiDKqSOogY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=d/+TltNQ8ORPSrhGXeg2bQTdrS8GNaESKLx+qAHeBox5igvAyIWqDto1u1qtJlA8u XOJ96TecQzizzNqPtl3YEJbyVrgv70a+nZTUx4ScC2EeGaq1sUWdz8lDmfDoqu3Wx4 M7uwTR6Mk+onFiLs0uN9WuFk0GW388KFnG6qICo+9KiDJWLvSsV/zj2ap+6p2ZSZa6 XiFv6mW/e/0+1K/ssGcvmov2C5DKZe01d6qeAEyt6vlV5QaB8hpo64XVRgRzNthF8O AlcJZV7XSECM/LFGLKd91p280FSo8llhpiocAW3N0147lXBGyF3aXJxGTQNDAVacFQ qVyYSY+lg2IpA== From: "David Hildenbrand (Arm)" To: stable@vger.kernel.org Cc: linux-mm@kvack.org, "David Hildenbrand (Red Hat)" , Rik van Riel , Laurence Oberman , Lorenzo Stoakes , Oscar Salvador , Liu Shixin , Harry Yoo , Lance Yang , "Uschakow, Stanislav" , Andrew Morton Subject: [PATCH 5.15.y 5/6] mm/rmap: fix two comments related to huge_pmd_unshare() Date: Wed, 18 Feb 2026 12:01:28 +0100 Message-ID: <20260218110129.41578-6-david@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260218110129.41578-1-david@kernel.org> References: <2026012608-tulip-moisten-c6f6@gregkh> <20260218110129.41578-1-david@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Stat-Signature: igu8ni1go73iqz71cniiw6hzazsnscib X-Rspam-User: X-Rspamd-Queue-Id: 16645180006 X-Rspamd-Server: rspam01 X-HE-Tag: 1771412513-564322 X-HE-Meta: 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 wiBjD8c3 uTG2AD9hzBgbPtG4uPnM/wVuXOsAbN4RFuSimXT40GYQlEQVVmr7quSs1Upcc3cU1z5x/vS4tDC63CW3DnO6LuNXMw9ntvf0cpTQjDmUzniDCj9+pn+3a/xeG7efxmBwxTQJi5I3umS0M9UMZSOol34vAj+EJgltY4Utd5Z8qPl648GQiS0rU/jh6TyBxw1m0neKBVrjMfmH6WMxpDyQf74FZ3lGyDCdW+IUiDqo9i+VXgV/gx5YCQUoNw56LQc+cWcUiRw0MXJZAarr8cbTe2fRFZCCPPcCBTUTZN2O5MgTbGlZcI3ZPn7VlavwRdPauNxHtg1L2bhl29uE61kb+Q3B5BhXKyEr8RqdYwpMfgIOPL8dMbUsCBVLVxSw9hlS1Enu2loBN2zhKBRGlBKfCkj20p1I9DxdDPYoJ4Zv2aMsR3jndt1OVXt3aNaQMkCzqgHd+nIQvBOclb7PCVTg4NiOYSw== 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: List-Subscribe: List-Unsubscribe: From: "David Hildenbrand (Red Hat)" PMD page table unsharing no longer touches the refcount of a PMD page table. Also, it is not about dropping the refcount of a "PMD page" but the "PMD page table". Let's just simplify by saying that the PMD page table was unmapped, consequently also unmapping the folio that was mapped into this page. This code should be deduplicated in the future. Link: https://lkml.kernel.org/r/20251223214037.580860-4-david@kernel.org Fixes: 59d9094df3d7 ("mm: hugetlb: independent PMD page table shared count") Signed-off-by: David Hildenbrand (Red Hat) Reviewed-by: Rik van Riel Tested-by: Laurence Oberman Reviewed-by: Lorenzo Stoakes Acked-by: Oscar Salvador Cc: Liu Shixin Cc: Harry Yoo Cc: Lance Yang Cc: "Uschakow, Stanislav" Cc: Signed-off-by: Andrew Morton (cherry picked from commit a8682d500f691b6dfaa16ae1502d990aeb86e8be) [ David: We don't have 40549ba8f8e0 ("hugetlb: use new vma_lock for pmd sharing synchronization") so there are some contextual differences. ] Signed-off-by: David Hildenbrand (Arm) --- mm/rmap.c | 18 ++++-------------- 1 file changed, 4 insertions(+), 14 deletions(-) diff --git a/mm/rmap.c b/mm/rmap.c index cb133bd49e02..5093d53f196e 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1489,13 +1489,8 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma, range.end); /* - * The ref count of the PMD page was dropped - * which is part of the way map counting - * is done for shared PMDs. Return 'true' - * here. When there is no other sharing, - * huge_pmd_unshare returns false and we will - * unmap the actual page and drop map count - * to zero. + * The PMD table was unmapped, + * consequently unmapping the folio. */ page_vma_mapped_walk_done(&pvmw); break; @@ -1808,13 +1803,8 @@ static bool try_to_migrate_one(struct page *page, struct vm_area_struct *vma, range.end); /* - * The ref count of the PMD page was dropped - * which is part of the way map counting - * is done for shared PMDs. Return 'true' - * here. When there is no other sharing, - * huge_pmd_unshare returns false and we will - * unmap the actual page and drop map count - * to zero. + * The PMD table was unmapped, + * consequently unmapping the folio. */ page_vma_mapped_walk_done(&pvmw); break; -- 2.43.0