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 EF1DC3A9D9A for ; Wed, 4 Feb 2026 19:55:40 +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=1770234941; cv=none; b=ortTvaC7ndzdNm8AypHtXIk7s3TvfFLNjx6pGllh1xvpTO/S3qPdUH4hApZ4oWupUc082i7onzvgKcySeqBc+di+1rHWytz33lNRhSZvsV2p8kbIgr7pjNrDwjI0R0decafmIZx/P31F/EGFHQnaTo0N/PhcuOl7bDH19SGDKAY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770234941; c=relaxed/simple; bh=E7SiYONFnBjZyoLuPb3bNROQr7xtT5319lNuGhJMu8U=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=coNv+tow+SwiQidaUnmuA0XvaUq8+f68fsXIHc9sM/6gcUYznS0R9f2LCK6KYju1DRvsqz5+qf9GqpagvyOJ7BrVZdBmUIJ443KcB/LUdF+YL1JIweLBAs3JsJUpNq0F/fOL2Bgqo7Ng54fy1Faa+ElrNlRPiZ1oHxMjUwVtFUI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=FCY+qiQ4; 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="FCY+qiQ4" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8CB4DC19424; Wed, 4 Feb 2026 19:55:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1770234940; bh=E7SiYONFnBjZyoLuPb3bNROQr7xtT5319lNuGhJMu8U=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=FCY+qiQ4jz8dDXY72EcyNZPUNF02EHNKLhG2vxQVyys5/9sxJ1IWZQeFgKoLYTvrs zdbqN+Z/E8RRnZxAbIeReMV0Z5ALIBbAVTch0Sbz8tf6mfxCPuNZddiuTJbsivZ+G+ 2bFQce5bI811bwFJeqSsSDrlC54QF0cj40ncm8eb6gH531NKOK3gj97S8COgBDy0m9 mtuhegW+6ENj5FKKYkC29/wii9otBm89zTiOL7wc6gWVQmaobDcW+jAw6Eko6H7M8m hHpCMoNzMQJJAbsByeR4F2kY0ur+E6rtjimP9GsankPiOrOwMRHq6BOolx1C0Z9C41 Nxf4L+b7/5cdA== Message-ID: <11399c99-f966-47be-bbb4-a7d4e79c8c38@kernel.org> Date: Wed, 4 Feb 2026 20:55:36 +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> <9E046323-740A-434A-8B60-B8A32D0955C0@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 20:48, Zi Yan wrote: > On 4 Feb 2026, at 14:18, David Hildenbrand (arm) wrote: > >> On 2/4/26 18:41, Zi Yan wrote: >>> >>> >>> 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. > > What do you mean? Changing memory failure code to only handle large_rmappable? > large_rmappable is a folio flag, memory failure code should see such Did you mean "should not" ? :) > non-folio but compound things to begin with, IMHO. I would say that we could right now reject in memory failure code any compound pages that do not have PG_large_rmappable set. I have the faint recollection that we don't set PG_large_rmappable on hugetlb folios yet, so they have to identified as well. > > I think we need to be able to tell between raw page (compound or not), > mappable page (compound or not, especially for those used with vm_insert_*), > and folio. We can't identify (small) folios just yet. We'd need another page flag for that (just like PG_large_rmappable), and we all know how that ends ;) With Willy's work we'll be able to identify folios reliably. How to deal with that vm_insert_* crap, especially for non-folio pages, is also future work based on that. -- Cheers, David