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Tue, 3 Nov 2026 15:00:58 +0000 (UTC) X-FDA: 85394120196.15.D1A1012 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf23.hostedemail.com (Postfix) with ESMTP id CB0FC14000F for ; Tue, 3 Nov 2026 15:00:56 +0000 (UTC) Authentication-Results: imf23.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=d3K6pDSF; spf=pass (imf23.hostedemail.com: domain of vbabka@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=vbabka@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=1793718056; 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:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=bA0DUmnnxVPUL6fKcA1U0PeMmih16OqQLXC+FqdAHTU=; b=JVZX/SUadzCG23S6GJcYGtRtsXd8ZslKjQwu531Pp1jGP3oyhBIxEV+cGETl17BRB6ZUjB giDuu2lxpiRLl7Rfkn47IQcIaV6S+ShWBzkO9mcAUL+L4+nlhfllxQx26CXIxUXJTx9Xs3 E4XV592DtMyP+NQwTaqtykru+yphGHE= ARC-Seal: i=1; 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b=d3K6pDSFh52zVCjIc/hBdsflRe5uFDEz0Fmn1nI+IKthHiXVq1OjvLBo8PS8Y7GfJ L6G5tw9QmaAoflgCwnDY08eRL/Ga120L9Q1f7tOGn94gVVV4Zdt/sQyCLyuZhP3Mxp UmONMR9peZ0sBrCDpOCrPthNxS+XUm5DPf7OZLwL9Rv3d3KK7VGugZs6A3VMEANKa9 OivpMxXoXJ/30qchLqIfmTlrvWU2x1m87FS8C82zMIbmuXeYq2tYTDcslOIE+U1x35 BgtTY9XjTURfxoHL+kKtzxrdkdqBnO9Ub7CK+2Z0a/9pA6XNBVVaMuIH942o52QY1U aLWb9/Wg3nTbA== Message-ID: Date: Tue, 3 Nov 2026 16:00:45 +0100 X-Archived-By: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5 07/12] mm/mmzone: read each zoneref slot once when filtering by nodemask Content-Language: en-US To: Zi Yan , "Gregory Price (Meta)" , linux-mm@kvack.org Cc: linux-trace-kernel@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@meta.com, akpm@linux-foundation.org, david@kernel.org, ljs@kernel.org, liam@infradead.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, kasong@tencent.com, qi.zheng@linux.dev, shakeel.butt@linux.dev, baohua@kernel.org, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, baoquan.he@linux.dev, baolin.wang@linux.alibaba.com, rientjes@google.com, rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, muchun.song@linux.dev, osalvador@suse.de, joshua.hahnjy@gmail.com, rakie.kim@sk.com, ying.huang@linux.alibaba.com, brendan.jackman@linux.dev, hannes@cmpxchg.org, bigeasy@linutronix.de, clrkwllms@kernel.org, nathan@kernel.org, ndesaulniers@google.com, morbo@google.com, justinstitt@google.com, Bessel.Wang@huawei.com, jiang.liu@huawei.com, mgorman@techsingularity.net, anshuman.khandual@arm.com, stable@vger.kernel.org References: <20261101021340.2251928-1-gourry@gourry.net> <20261101021340.2251928-8-gourry@gourry.net> From: "Vlastimil Babka (SUSE)" Autocrypt: addr=vbabka@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-17.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=4.0.1 X-Rspamd-Server: rspam09 X-Stat-Signature: yag4enq6ypsb5myx3aonxdp4m8booh9c X-Rspamd-Queue-Id: CB0FC14000F X-Rspam-User: X-HE-Tag: 1793718056-563149 X-HE-Meta: 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 Y/6YPJgZ GhPPE5qKL2o6QSD9xT3UNz9VCKI5Qlb3YdP5yVvPYWrFDKA8cKES01jYHdCAvKmHCGNQk4Va3HZb1COxXGWA+0sQ9b4WYevK0V0MtnhiIHZPXsKtSXNM61h43fAdUunoFGbIFo/ul/TCnieiNqgGyYeBFwpAQkCj5eg6NbfgnS42nay1RoM9tMQlBlXFxkxb70ZpSwwwXCqaaid2+DCyZGg+3g6X9QyOK7Lq0PDWbodFKLSrTMZKIQrCOuWlvci/eNN+qLtecva/TZOMrcd1Ej35CacSRta5jPvqJ8u4xvHorEJOnlgfLmeEAurvS++zcn0Hipvw/Ju7Hb8EhsdXxPsl5eKIpEr7OpOAwzsgx+h1LFvXwtm071NefKcufb2b1IzUOTb4ZuTxUo4hFrEoZv3fJ6nyh5HG4VM6eQVQU2LJZQiRT0Ij93Ynsaw== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On 11/3/26 04:01, Zi Yan wrote: > On Sat Oct 31, 2026 at 10:13 PM EDT, Gregory Price (Meta) wrote: >> __next_zones_zonelist() tests a slot's zone for NULL, then reads the >> slot again to look up the zone's node. Offlining a zone's last block >> rebuilds the zonelists in place, so the second read can return the >> terminator: >> >> CPU 0 CPU 1 >> __next_zones_zonelist(nodemask) >> zonelist_zone(slot 1) = NORMAL >> offline_pages() >> build_all_zonelists() >> [MOVABLE, NORMAL, NULL] >> -> [NORMAL, NULL] >> zref_in_nodemask(slot 1) >> zone_to_nid(NULL) >> >> Current GCC and clang merge the two reads, but nothing requires it. >> With mm/mmzone.o built with -fno-inline -fno-ipa-sra, holding a >> nodemask allocation between the reads while the node's last movable >> block goes offline oopses every time: >> >> BUG: kernel NULL pointer dereference, address: 0000000000000060 >> RIP: 0010:zone_to_nid+0x0/0x10 >> Call Trace: >> zref_in_nodemask+0x9/0x20 >> __next_zones_zonelist+0x23/0x70 >> prepare_alloc_pages.constprop.0+0x16c/0x190 >> __alloc_frozen_pages_noprof+0xaf/0x330 >> >> Read the slot once and test that zone. A NULL zone still ends the walk. > > It is better to spell out the rename from zref_in_nodemask() to > zone_in_nodemask(). Added: To achieve that, rename zref_in_nodemask() to zone_in_nodemask() and pass a zone instead of zoneref pointer. > >> >> Fixes: 11cd8638c37f ("mm, page_alloc: remove stop_machine from build_all_zonelists") >> Cc: stable@vger.kernel.org >> Signed-off-by: Gregory Price (Meta) >> Reviewed-by: Vlastimil Babka (SUSE) >> --- >> mm/mmzone.c | 11 ++++++----- >> 1 file changed, 6 insertions(+), 5 deletions(-) >> > > Makes sense. > > Reviewed-by: Zi Yan > >