From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 5B59D347BD1 for ; Wed, 4 Feb 2026 19:18:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770232699; cv=none; b=DcVq/aSeISHx+XxsdxaQnuvtnoey/ARwA6+jo3AwzEvBmidIMyaHbzhCSBdhwqkxHbeJWkidcm/O38lIehtiqZ7Dw4lKluSzt7w+OVpAS/WHGCD4iExBMFVjLnqXUi5zK+ULdH9Gk40U+aRQRAwMkTZU2Oe89tPSsof/RSSlz/s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770232699; c=relaxed/simple; bh=avzQCaqFUqyIXFQfYFCxUvMl0Dj3mQFAIfQxWIjWZ3c=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=fd1mxPO+EhQF8O0FJpTPEzOA8jsU3UsdK7aWgfNJeozjtWl/3GI4Ex9JQz09G87B86zyf9rb2JdMRCtPAIk4QxmKCUrTNgvGPS4VPRffCY2Fvs6tN40cKiunDzoGWCmI8C6vHBj2rQtuO1xo3pROHMSoLFyuDmE/iRE0H+zohOY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Sb130OWg; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Sb130OWg" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 212D3C4CEF7; Wed, 4 Feb 2026 19:18:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1770232699; bh=avzQCaqFUqyIXFQfYFCxUvMl0Dj3mQFAIfQxWIjWZ3c=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=Sb130OWgpLFTr086vbrLVXDhGiRA2dFSsHxqYeZBWauuRNcSjrFQrGGAtw5EDC35W Ak5kGmct0g6a7aLxgxxFzmcA5klESXyRsveDz02QnGkV/ivzRCLyULq5U7eh7qjmSp 0A0tGP+WpQ5RopLOLvHQrZoMHPGQ+2Ca1vMNfLQxeKhw89KSR4Xy7e+lo2fC9XEh4+ 4G9zU13ZEDYzRHTJaolR730wl1UjowNWpni0qSvubT3UrCLo0zD5Iq7P0UKP+TAv8Q nMHrIOOL/cCP3jYgh4equZva18wEsxoivNzug1cqropFjNpfOPDYX2lUH3KVhJX9W9 +//n0WlqHinqg== Message-ID: Date: Wed, 4 Feb 2026 20:18:14 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: WARNING in memory_failure() at include/linux/huge_mm.h:635 triggered To: Zi Yan Cc: =?UTF-8?B?5piv5Y+C5beu?= , linux-mm@kvack.org, linmiaohe@huawei.com, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, Matthew Wilcox References: <1db245a8-f9ab-42e4-8cc6-cc7562961921@kernel.org> <48978612-6933-4897-85DD-6740B6C8570B@nvidia.com> <25CA4D90-A24E-49C6-92D2-08080EC81466@nvidia.com> <032058DC-CD8D-406A-B986-740E41C834B2@nvidia.com> From: "David Hildenbrand (arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 2/4/26 18:41, Zi Yan wrote: > On 4 Feb 2026, at 12:34, Zi Yan wrote: > >> On 4 Feb 2026, at 12:23, Zi Yan wrote: >> >>> >>> >>> From the C repro above, syzbot opened a dev "/dev/sg#" and did mmap on it. >>> Is it a device driver issue? >> >> OK, it is CONFIG_CHR_DEV_SG. And the driver allocates a compound page at[1]. >> Since we initialize folio fields in prep_compound_page(), it becomes a folio >> when it is inserted into a VMA. > > More details: > later at sg_vma_fault(), the driver just handles a page fault by supplying > a subpage from a pre-allocated compound page[3]. We then get a large folio > without !CONFIG_TRANSPARENT_HUGEPAGE. We can identify such non-folio (but compound) things by looking at PG_large_rmappable IIRC. -- Cheers, David