From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=91.218.175.126 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794198839; b=V2Dmk8GfxUBjMIiJwDkc92OW2m4QWnLzABF5tOq++PD5u+gyHxpf/CLJm6snw5p33yLn GeFTQZKINIfMIVZ+QZQahGNYRJ3ikRzieM6NGLI4gLuKdf62GyrI2MB1nMLzVCaYyh/zn QBMKPOe2ZwFjcmm/STgz9csTRmmeADcX4lApU5fGTcso9BkFLTHcRq5MG81beNmW+tNNX FLLEi/0ZKEml/zpIJXb2S20QN64UFgP7DynIM5giMmBQF0dTRKwdEtFJA92DtIL6nLBdk OeUBCxG4Lnt08bX7f0zebia+yyY+JgBy/Srh3N1saLfnndJriEtE0aBf22h/TatDmVg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794198839; h=DMARC-Filter:X-Envelope-To:DKIM-Signature:X-Envelope-To:Received: X-Mizu-Trace-ID:X-Migadu-Flow:From:To:Cc:Subject:Date:Message-ID: X-Mailer:In-Reply-To:References:MIME-Version:Content-Type: Content-Transfer-Encoding; bh=4DN1Y+t6vujW8S/AQPbCJ490d9V4hkbmm812BgwtOTM=; b=giGuVGMpj/c6Ayzc/OfGy8mdlRCtcP9RBKPj7JxMrXP1pwxJQJpEMfFji3HJyhU2ryNr /GRRw07PPMcWJjt7mKu8LQyUf03BAwSgAtkpaLrbbpucsugTxvxThVBjYEGMw+/C21oCO skjSun+picxukvw5X/hM30Mi/2EMb+24O1FhI1WEUv0Z+Ffky4TCifT62cVLObJwAHmml /qxnMFfnQHaghPl6SEEZlCG1SHUofPi8C2CpvwO8Akb9itrnnwwA+yjnQfIocT89AnrlV ua/VBoJ4mYqmeOsI3PvniddUDUHFXzrNeYnkwRoZP8Sxgai1KDQ5j5s6AxtlISfV+pg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=J+aTWeug; arc=none smtp.remote-ip=91.218.175.126 Received: from mta0.migadu.com (out-126.mta0.migadu.com [91.218.175.126]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 819FE606A322 for ; Mon, 9 Nov 2026 04:33:58 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 819FE606A322 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=J+aTWeug X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=Uhs7BWZm2N+gFKXL/TmYjVQYKnl8VlxGISFVM5NLm40=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1794198836; v=1; x=1794803636; b=J+aTWeugil4lbZaw86bysXlj72KJ1YDD/oBtNnrnxpwFt1Zv3v92oWKWjh4hCRQhawyW6UvD SrnwHPTpMGnc32HdDCtbC3titUBPWUSWN+J0XGBgJevyXUJILOhMtgkDhR1TxBlSmyoG0ILcNWb 71MK+oj5lMtq7adOxfFCoBjg= X-Envelope-To: linux-kernel@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id b7fb94620bed6bfe; Mon, 09 Nov 2026 04:33:56 +0000 X-Mizu-Trace-ID: b7fb94620bed6bfe X-Migadu-Flow: FLOW_OUT From: Lance Yang To: songmuchun@bytedance.com Cc: david@kernel.org, maddy@linux.ibm.com, rppt@kernel.org, akpm@linux-foundation.org, lance.yang@linux.dev, mpe@ellerman.id.au, npiggin@gmail.com, chleroy@kernel.org, ritesh.list@gmail.com, sshegde@linux.ibm.com, osalvador@suse.de, qi.zheng@linux.dev, muchun.song@linux.dev, chenhuacai@kernel.org, kernel@xen0n.name, linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-riscv@lists.infradead.org, x86@kernel.org, loongarch@lists.linux.dev, linux-s390@vger.kernel.org Subject: Re: [PATCH v3 3/5] loongarch/mm: disable device DAX vmemmap optimization Date: Mon, 9 Nov 2026 12:33:46 +0800 Message-ID: <20261109043346.38778-1-lance.yang@linux.dev> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20261107043122.25650-4-songmuchun@bytedance.com> References: <20261107043122.25650-4-songmuchun@bytedance.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On Sat, Nov 07, 2026 at 12:31:20PM +0800, Muchun Song wrote: >LoongArch selects ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP but not >ARCH_WANT_OPTIMIZE_DAX_VMEMMAP. Its vmemmap_free() implementation is also >empty, so it cannot tear down optimized Device DAX mappings. > >A later change removes the generic Device DAX architecture gate and lets >vmemmap_populate() decide whether a section can use optimization. Clear the >section compound order in the LoongArch path so Device DAX keeps using >unoptimized mappings. > >This does not affect HugeTLB HVO: LoongArch does not support gigantic >pages, so HugeTLB does not use section-based vmemmap optimization there. > >Signed-off-by: Muchun Song >--- >v2: >- New patch using section_vmemmap_optimization_disable() to keep Device > DAX vmemmap optimization disabled on LoongArch (reported by Sashiko) >--- > arch/loongarch/mm/init.c | 2 ++ > 1 file changed, 2 insertions(+) > >diff --git a/arch/loongarch/mm/init.c b/arch/loongarch/mm/init.c >index f801f7097f03..ea769e479241 100644 >--- a/arch/loongarch/mm/init.c >+++ b/arch/loongarch/mm/init.c >@@ -15,6 +15,7 @@ > #include > #include > #include >+#include > #include > #include > #include >@@ -143,6 +144,7 @@ void __meminit vmemmap_set_pmd(pmd_t *pmd, void *p, int node, > int __meminit vmemmap_populate(unsigned long start, unsigned long end, > int node, struct vmem_altmap *altmap) > { >+ section_vmemmap_optimization_disable(start, end); Yeah, clearing the order here keeps Device DAX optimization disabled once the generic gate goes away ;) Nothing jumped out at me, feel free to add: Reviewed-by: Lance Yang