From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=91.218.175.6 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793326931; b=zek8dhdwl6kxhe2RBLPEtZFDVHmlcUrWRhNTG08gX2rYNY9FGSt0ikYTxfI7Kgbl4qXW y5o0SVSQlCL862QagLV7grNs3p3yYpkhZk0YnOUuQMcT/2yBvN5Q/gtocXZFr4PO727r3 yJqoq7mi1JkYT4j0UwIs0fr8Gda9wZYb3lkeRhjXnqd1fOS1I2q7n5aWMrpXriLUUmfwk boKv3dBHNUxLgaUbOaa8MHTIc9ET+dz6q/G66W9HzHifZhS8H+yy61fQ6KAhxVrjA61KO mLT7Tr30ADUyZrpMDJrA/tNa/2gMsoXeWdMoJL5RbX0CYlmmqXy+6XR43moVrxqYLqQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793326931; h=DMARC-Filter:X-Envelope-To:DKIM-Signature:X-Envelope-To:Received: X-Mizu-Trace-ID:X-Migadu-Flow:Content-Type:Mime-Version:Subject:From: In-Reply-To:Date:Cc:Content-Transfer-Encoding:Message-Id:References: To:X-Mailer; bh=GuCXOFg/eaPoMDDOQ3AZlcKE9moyp2CTPmKEIesl8bI=; b=UvwA6+fk4+SblRCWbOAfRuDWVUVhjb4Viq9vibHtIYN9DHlBtszXjIGsgvogL6hsao7F nwQSdgIzlEtOK+8cOyPXEwyaw3qrqdVoqfHBaHWggr8bNSBX5kQgjDccTn+O2oHDUDwYR qbod1E18lyfsHOiYvJFnsax1Saeydx8wOCOQwmXTFGzCyt21hLrw2nvV4cOGP5mpgyiF5 +Jjf7FrjBdgP/fFyFHJGkzKq6Jr2xG5P6seamlQOM5Am/Xcsp90dKm4/aaAKsIF65+N4N jfebIu/U9Fey7R41gIHDwZMiYYNVw7ryw7k3hCyQvY8HNpo9ntuvp89WKKW275YMPtQ== 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=QmZfN2jP; arc=none smtp.remote-ip=91.218.175.6 Received: from mta0.migadu.com (out-6.mta0.migadu.com [91.218.175.6]) (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 4C28A606A323 for ; Fri, 30 Oct 2026 02:22:08 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 4C28A606A323 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=QmZfN2jP X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=3W7i1+QOf/eQW3A33+hQoH7jzxTnHmjxgFZBOXgW78U=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1793326927; v=1; x=1793931727; b=QmZfN2jP4dUxZiSnaSdskWPARHinFT7ZQjige5i32RhnTdt4N/azDq2U0wo/Qo+edWEqH/dr wTcZ9xnxq0+TcBW1ZiGbvdN0hfQwM6QskzlG829WFPm+f6byXk7j16RBEoGB9JMu9iSQCdQdntl jbux+ZLv64nT6pKsqXoD95M4= X-Envelope-To: linux-kernel@vger.kernel.org Received: by mta12.migadu.com with ESMTPS id bb3320411df55916; Fri, 30 Oct 2026 02:22:07 +0000 X-Mizu-Trace-ID: bb3320411df55916 X-Migadu-Flow: FLOW_OUT Content-Type: text/plain; charset=us-ascii 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 (Mac OS X Mail 16.0 \(3901.100.1.1.12\)) Subject: Re: [PATCHv2] mm/huge_memory: set the mmu_gather page size in zap_huge_pud() From: Muchun Song In-Reply-To: <8b853e5f9f16145859407b28af654b0f79e12642.1793318297.git.ritesh.list@gmail.com> Date: Fri, 30 Oct 2026 10:21:49 +0800 Cc: linux-mm@kvack.org, Andrew Morton , Madhavan Srinivasan , Venkat Rao Bagalkote , linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, David Hildenbrand , Zi Yan , Baolin Wang , Pavithra Content-Transfer-Encoding: quoted-printable Message-Id: <4012569A-93C1-4662-B6A3-3521B97B8C57@linux.dev> References: <8b853e5f9f16145859407b28af654b0f79e12642.1793318297.git.ritesh.list@gmail.com> To: "Ritesh Harjani (IBM)" X-Mailer: Apple Mail (2.3901.100.1.1.12) > On Oct 30, 2026, at 08:07, Ritesh Harjani (IBM) = wrote: >=20 > Unmapping a device-dax mapping with 1G alignment on powerpc radix = kernel > built with CONFIG_DEBUG_VM triggers this warning on every munmap: >=20 > WARNING: mm/mmu_gather.c:176 at = __tlb_remove_folio_pages_size+0x38/0x230 > NIP [c00000000063d508] __tlb_remove_folio_pages_size+0x38/0x230 > LR [c0000000006fb688] zap_huge_pud+0x1b8/0x2d0 > Call Trace: > zap_huge_pud+0x170/0x2d0 (unreliable) > __zap_vma_range+0x1604/0x1e20 > unmap_vmas+0xa0/0x1f0 > unmap_region+0xb0/0x130 > vms_complete_munmap_vmas+0x120/0x310 > do_vmi_align_munmap+0x1ec/0x240 > __vm_munmap+0x148/0x220 > sys_munmap+0x28/0x40 >=20 > To trigger this - it is enough to mmap() /dev/dax0.0, touch the first > byte so that the whole 1G is mapped by a single PUD and then munmap() > it. >=20 > PowerPC needs MMU_GATHER_PAGE_SIZE in which mmu_gather needs to record > the page size for which tlb flush is needed. zap_huge_pmd(), > zap_pte_range(), change_huge_pud() etc all do this already. However, > since commit: > dbe54153296d ("mm/huge_memory: add vmf_insert_folio_pud()") >=20 > a device-dax PUD maps a real folio and zap_huge_pud() now hands it to > tlb_remove_page_size(tlb, page, HPAGE_PUD_SIZE). At that point > tlb->page_size is still whatever the previous user left behind, which = is > 0 for the fresh gather set up by munmap() and so the check fires. >=20 > Fix this in the same way like how other similar paths do. >=20 > Fixes: dbe54153296d0 ("mm/huge_memory: add vmf_insert_folio_pud()") > Reported-by: Pavithra > Signed-off-by: Ritesh Harjani (IBM) Acked-by: Muchun Song Thanks.