From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B0FC7234994 for ; Mon, 21 Sep 2026 06:15:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789971347; cv=none; b=iQ/d9Wz6noqdeICZU/CrQ/BevR7VBh+mOzjWBcR9tuYpcjIF917btN56y50D5u5+WKLXnsNrGtVrgWTYqM+ZtI3pb4205Lv4R5qMPicHGKnUeiI4M5s7CKaPfZcOTgmjh0JkD02PvnR+ng/Fn0BrnJib6W+v1mxx3Wd5kZkdFKQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789971347; c=relaxed/simple; bh=U+BZmlJlH6/QGjrxwSWeU2Y5vyPujkdpXIzRyUEOJ+A=; h=Date:To:From:Subject:Message-Id; b=EsL8uLXC+OvEI51eAWjQ1VxXdr1q/yJiQkhGiXjPIdT9jY3d+OzMj7CX6OdNpnBD9pSnZvLMveJws/VwzfdBcHxQ0ha38eH+Nl6bkrqychL4abmTmF+wOGvywuoemSHmIgMZXN2xGhtY707RmOOBn0s/FVGujgKxT+UYVnjWnI0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=vVJkIG21; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="vVJkIG21" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 32E5D1F000FF; Mon, 21 Sep 2026 06:15:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1789971345; bh=bR8yO+YIF8tuYtS7lXTO2zAltGICyiLCQv4bX9ID3Cg=; h=Date:To:From:Subject; b=vVJkIG21pWWkGNqIAW1XEZLhh2j+U0ThWnZP8GWqOX/35VNXvqYdAzzeUdgnCm/3m HrLN8u8nx1SCdF7zgU3i9kSEJ2STZBPfprZX1XTSVYFipinOFSDZGARbq2sF7jLBWY mmv3gFfCmmJnHskJgMtDsmRwW47txzhAl0TQQgzs= Date: Sun, 20 Sep 2026 23:15:44 -0700 To: mm-commits@vger.kernel.org,ziy@nvidia.com,vbabka@kernel.org,usama.arif@linux.dev,surenb@google.com,ryan.roberts@arm.com,rppt@kernel.org,nico.pache@linux.dev,mhocko@suse.com,ljs@kernel.org,liam@infradead.org,kas@kernel.org,dev.jain@arm.com,david@kernel.org,baolin.wang@linux.alibaba.com,baohua@kernel.org,lance.yang@linux.dev,akpm@linux-foundation.org From: Andrew Morton Subject: + mm-disallow-raw-pfn-mappings-of-huge-shared-zeropage.patch added to mm-new branch Message-Id: <20260921061545.32E5D1F000FF@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: mm: disallow raw PFN mappings of huge/shared zeropage has been added to the -mm mm-new branch. Its filename is mm-disallow-raw-pfn-mappings-of-huge-shared-zeropage.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-disallow-raw-pfn-mappings-of-huge-shared-zeropage.patch This patch will later appear in the mm-new branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Note, mm-new is a provisional staging ground for work-in-progress patches, and acceptance into mm-new is a notification for others take notice and to finish up reviews. Please do not hesitate to respond to review feedback and post updated versions to replace or incrementally fixup patches in mm-new. The mm-new branch of mm.git is not included in linux-next If a few days of testing in mm-new is successful, the patch will me moved into mm.git's mm-unstable branch, which is included in linux-next Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via various branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there most days ------------------------------------------------------ From: Lance Yang Subject: mm: disallow raw PFN mappings of huge/shared zeropage Date: Mon, 21 Sep 2026 13:42:25 +0800 Handling the huge/shared zeropage correctly in vmf_insert_pfn_pmd() and vmf_insert_pfn_prot() is more involved. We would need to check whether the VMA allows it and keep the mapping read-only, similar to the checks in vm_mixed_ok(). No in-tree user needs that support, so reject these mappings with VM_FAULT_SIGBUS rather than complicate the code for now. Link: https://lore.kernel.org/20260921054225.28537-1-lance.yang@linux.dev Link: https://lore.kernel.org/all/20260917121010.60966-1-lance.yang@linux.dev/ Signed-off-by: Lance Yang Signed-off-by: Andrew Morton Suggested-by: Kiryl Shutsemau (Meta) Suggested-by: David Hildenbrand (Arm) Reviewed-by: Kiryl Shutsemau (Meta) Cc: Baolin Wang Cc: Barry Song Cc: Dev Jain Cc: Liam Howlett Cc: Lorenzo Stoakes (ARM) Cc: Michal Hocko Cc: "Mike Rapoport (IBM)" Cc: Nico Pache (Red Hat) Cc: Ryan Roberts Cc: Suren Baghdasaryan Cc: Usama Arif Cc: "Vlastimil Babka (SUSE)" Cc: Zi Yan --- mm/huge_memory.c | 3 +++ mm/memory.c | 3 +++ 2 files changed, 6 insertions(+) --- a/mm/huge_memory.c~mm-disallow-raw-pfn-mappings-of-huge-shared-zeropage +++ a/mm/huge_memory.c @@ -1723,6 +1723,9 @@ vm_fault_t vmf_insert_pfn_pmd(struct vm_ (VM_PFNMAP|VM_MIXEDMAP)); BUG_ON((vma->vm_flags & VM_PFNMAP) && vma_is_cow_mapping(vma)); + if (unlikely(is_huge_zero_pfn(pfn))) + return VM_FAULT_SIGBUS; + pfnmap_setup_cachemode_pfn(pfn, &pgprot); return insert_pmd(vma, addr, vmf->pmd, fop, pgprot, write); --- a/mm/memory.c~mm-disallow-raw-pfn-mappings-of-huge-shared-zeropage +++ a/mm/memory.c @@ -2956,6 +2956,9 @@ vm_fault_t vmf_insert_pfn_prot(struct vm BUG_ON((vma->vm_flags & VM_PFNMAP) && vma_is_cow_mapping(vma)); BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn)); + if (unlikely(is_zero_pfn(pfn))) + return VM_FAULT_SIGBUS; + if (addr < vma->vm_start || addr >= vma->vm_end) return VM_FAULT_SIGBUS; _ Patches currently in -mm which might be from lance.yang@linux.dev are mm-huge_memory-simplify-pgtable-deposit-detection.patch mm-disallow-raw-pfn-mappings-of-huge-shared-zeropage.patch