From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E21D3606A326 for ; Mon, 2 Nov 2026 11:44:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=lists.infradead.org header.i=@lists.infradead.org header.a=rsa-sha256 header.s=bombadil.20210309 header.b=EwaeOfAJ; dkim=pass (1024-bit key, unprotected) header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=Zb1GeGbo DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:Cc: To:From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Unsubscribe-Post: List-Owner; bh=who8ZKKpx/jTygdDf46XygrUGTNQ5Ti9QGrea7MK2kQ=; b=EwaeOfAJ+So4wb 76zHbAMgHxNbysgCFjbwvHDa4Vs1yfSAWI0PlpmIcL125uzVXiawgbaAufhQ+hXmQfutpsxx50z2Y NqKiigcSf8oN5SJXeL2DZywW2ujeVccioDlZ11g16LipoSUET0FNWda09dgCCoN9HXyKUWQFCMlpH 59SlPyNin+fepY1IDSNLIHT2Nn3aNPtqg1Z7THGomKrC6QhdxakHhWxksFtWqFR1Gx7oSD7CN1Pc2 tTn6vLrMia/MHx3nV4fE+5uBMWgktg7LimS55sc6fO4Hq4BH2o1zV8Y3Uvwa/aVt6Th1qIci/G2WY QcEl5Oo34A+FJaybU+lA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.100.1 #2 (Red Hat Linux)) id 1xNqTA-0000000GNf1-2uzz; Mon, 02 Nov 2026 11:44:56 +0000 Received: from out-143.mta1.migadu.com ([2001:41d0:203:375::8f] helo=mta1.migadu.com) by bombadil.infradead.org with esmtps (Exim 4.100.1 #2 (Red Hat Linux)) id 1xNqT8-0000000GNdW-0soa for kexec@lists.infradead.org; Mon, 02 Nov 2026 11:44:55 +0000 X-Envelope-To: kexec@lists.infradead.org DKIM-Signature: a=rsa-sha256; bh=fgRhZQDSEmJFZyIgGkSRYKnhjZ4Z1l5m8LV8w/ZXnHw=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1793619890; v=1; x=1794224690; b=Zb1GeGbojxXveT3cZxDPn//4R8A7h+RMO72HLl435m67FVvM9SHf44yaVVp55n3SAPWWoirq Hz8XE56QJlzs5IpeJmF7MvIRESwEWtyXzDq/oA5mLYy34SDIJOr+HdZ4EG3OGTtz9aHGD3cJfWY yqj/TBZodxsUUHX+M5Y8plAE= X-Envelope-To: kexec@lists.infradead.org Received: by smtp.migadu.com with ESMTPS id 6ed161f8dd0a3c59; Mon, 02 Nov 2026 11:44:49 +0000 X-Mizu-Trace-ID: 6ed161f8dd0a3c59 X-Migadu-Flow: FLOW_OUT From: Lance Yang To: david@kernel.org Cc: akpm@linux-foundation.org, hannes@cmpxchg.org, mhocko@kernel.org, qi.zheng@linux.dev, shakeel.butt@linux.dev, ljs@kernel.org, kasong@tencent.com, baohua@kernel.org, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, baoquan.he@linux.dev, baolin.wang@linux.alibaba.com, liam@infradead.org, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, kees@kernel.org, peterz@infradead.org, jannh@google.com, pfalcato@suse.de, hughd@google.com, pasha.tatashin@soleen.com, pratyush@kernel.org, willy@infradead.org, jack@suse.cz, ziy@nvidia.com, lance.yang@linux.dev, riel@surriel.com, harry@kernel.org, apopple@nvidia.com, nico.pache@linux.dev, ryan.roberts@arm.com, dev.jain@arm.com, usama.arif@linux.dev, kas@kernel.org, matthew.brost@intel.com, jhubbard@nvidia.com, peterx@redhat.com, will@kernel.org, aneesh.kumar@kernel.org, npiggin@gmail.com, osalvador@suse.de, minchan@kernel.org, muchun.song@linux.dev, xu.xin@linux.dev, chengming.zhou@linux.dev, chrisl@kernel.org, shikemeng@huaweicloud.com, nphamcs@gmail.com, youngjun.park@lge.com, gourry@gourry.net, joshua.hahnjy@gmail.com, rakie.kim@sk.com, ying.huang@linux.alibaba.com, jgg@ziepe.ca, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kexec@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linux-cxl@vger.kernel.org, stable@vger.kernel.org, usama.anjum@arm.com Subject: Re: [PATCH v3 30/47] mm/mremap: use pudp_huge_get_and_clear() when moving huge PUDs Date: Mon, 2 Nov 2026 19:44:42 +0800 Message-ID: <20261102114442.65682-1-lance.yang@linux.dev> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20261031-fixes_core-v3-30-d6437171ecc3@kernel.org> References: <20261031-fixes_core-v3-30-d6437171ecc3@kernel.org> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20261102_034454_386814_D7FE0FBC X-CRM114-Status: UNSURE ( 9.71 ) X-CRM114-Notice: Please train this message. X-Spam-Score: -2.1 (--) X-BeenThere: kexec@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "kexec" X-Spam-Status: No, score=-18.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On Sat, Oct 31, 2026 at 10:39:59AM +0100, David Hildenbrand (Arm) wrote: >move_huge_pud() reads the old PUD and clears it in separate operations. >Hardware accessed or dirty updates between those operations can be lost >when the saved entry is installed at the new address. Yep. HW can still update the A/D bits while the PUD lock is held :) >The raw pud_clear() also bypasses page_table_check_pud_clear(), while >set_pud_at() accounts for the destination mapping. This leaves the >checker counts unbalanced for mappings tracked by page table checking. > >To fix it, simply use pudp_huge_get_and_clear(). > >Fixes: 7d846db7d0e2 ("mm/mremap: convert huge PUD move to separate helper") >Cc: stable@vger.kernel.org >Reviewed-by: Lorenzo Stoakes (ARM) >Reviewed-by: Pedro Falcato >Reviewed-by: Dev Jain >Tested-by: Muhammad Usama Anjum >Signed-off-by: David Hildenbrand (Arm) >--- > mm/mremap.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > >diff --git a/mm/mremap.c b/mm/mremap.c >index 0d06d7f37f19a..16e736c72d9cb 100644 >--- a/mm/mremap.c >+++ b/mm/mremap.c >@@ -509,8 +509,7 @@ static bool move_huge_pud(struct pagetable_move_control *pmc, > spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING); > > /* Clear the pud */ >- pud = *old_pud; >- pud_clear(old_pud); >+ pud = pudp_huge_get_and_clear(mm, pmc->old_addr, old_pud); Reviewed-by: Lance Yang > > VM_BUG_ON(!pud_none(*new_pud)); > > >-- >2.43.0 > >