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 427873D6498; Wed, 13 May 2026 07:53:12 +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=1778658793; cv=none; b=kRL7lixMV5w0jUz+j8n1YscxOSo8tetg0zTrNagvUqjww0pFFu6dSfpObn1oP8S0jRmqk8GewlgbIJTgRcHZ3HXP6AfhvebUnGIRiDvGBSZboF1wvVW3VzXw7pN6RGmyNZZQlBWEJXXQgZ6gjk/danb+M7QPnfEQ6tuWSSOFkok= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778658793; c=relaxed/simple; bh=6iyqWy4rHTiKW7ZdrWzQSt3Q4mjVireoFhoNPjhDEfg=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=HJGQIGre+qFRXB/JBlCyQ0gsVZnvmBBxhFErM89pl3rX0b/vy+JRUkXPk9LVtGjaBBaAp7bDTeHq+hI7UOJFQs/xyzOa1kIkgesQPOq8L4PoTRkXjS/zVMgX2pjAO52RcyJTHCbcL9Nb9crMgfCTI254SwXC96cle8FnsqivcUM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=EniW94al; 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="EniW94al" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0DE31C2BCC7; Wed, 13 May 2026 07:53:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1778658792; bh=6iyqWy4rHTiKW7ZdrWzQSt3Q4mjVireoFhoNPjhDEfg=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=EniW94albia7ugNShZyT9/dAuvZIgetNjErVBCbjIB737fV64xbAQle1UPDQ0Njuy s40Kg7V+FglbWMBWGiHXYDLZj+yd7neQL5Hg4bu/d9GTMzBdg0vcY/F9TeFES/TRcl hUc53o7ShxTY6xMMGneDENZKlfefYSrrWci+Z7ByZutENRYyKtvSi55dHbMpYf1u69 yjFRily+Y/yCHk0DQO9t6cYftG4sje3NGlKQfQUjP/aMFENy2D4gNAqsxkU3cUzlLz zt/ashq4JTa+THVzpTD2aA2qKMtSsJczJW5xwn4WDz+0btToJ7dj6NYLNJlsGkQXym 6pwY1/HPRnqRQ== Message-ID: Date: Wed, 13 May 2026 09:53:03 +0200 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: [PATCH v6 1/4] mm/memory-failure: report MF_MSG_KERNEL for reserved pages To: Breno Leitao Cc: Miaohe Lin , Naoya Horiguchi , Andrew Morton , Jonathan Corbet , Shuah Khan , Lorenzo Stoakes , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Shuah Khan , Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , "Liam R. Howlett" , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-trace-kernel@vger.kernel.org, kernel-team@meta.com, Lance Yang References: <20260511-ecc_panic-v6-0-183012ba7d4b@debian.org> <20260511-ecc_panic-v6-1-183012ba7d4b@debian.org> <9504c193-8c01-4d03-8f62-c50fd7fbdbc0@kernel.org> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzS5EYXZpZCBIaWxk ZW5icmFuZCAoQ3VycmVudCkgPGRhdmlkQGtlcm5lbC5vcmc+wsGQBBMBCAA6AhsDBQkmWAik AgsJBBUKCQgCFgICHgUCF4AWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaYJt/AIZAQAKCRBN 3hD3AP+DWriiD/9BLGEKG+N8L2AXhikJg6YmXom9ytRwPqDgpHpVg2xdhopoWdMRXjzOrIKD g4LSnFaKneQD0hZhoArEeamG5tyo32xoRsPwkbpIzL0OKSZ8G6mVbFGpjmyDLQCAxteXCLXz ZI0VbsuJKelYnKcXWOIndOrNRvE5eoOfTt2XfBnAapxMYY2IsV+qaUXlO63GgfIOg8RBaj7x 3NxkI3rV0SHhI4GU9K6jCvGghxeS1QX6L/XI9mfAYaIwGy5B68kF26piAVYv/QZDEVIpo3t7 /fjSpxKT8plJH6rhhR0epy8dWRHk3qT5tk2P85twasdloWtkMZ7FsCJRKWscm1BLpsDn6EQ4 jeMHECiY9kGKKi8dQpv3FRyo2QApZ49NNDbwcR0ZndK0XFo15iH708H5Qja/8TuXCwnPWAcJ DQoNIDFyaxe26Rx3ZwUkRALa3iPcVjE0//TrQ4KnFf+lMBSrS33xDDBfevW9+Dk6IISmDH1R HFq2jpkN+FX/PE8eVhV68B2DsAPZ5rUwyCKUXPTJ/irrCCmAAb5Jpv11S7hUSpqtM/6oVESC 3z/7CzrVtRODzLtNgV4r5EI+wAv/3PgJLlMwgJM90Fb3CB2IgbxhjvmB1WNdvXACVydx55V7 LPPKodSTF29rlnQAf9HLgCphuuSrrPn5VQDaYZl4N/7zc2wcWM7BTQRVy5+RARAA59fefSDR 9nMGCb9LbMX+TFAoIQo/wgP5XPyzLYakO+94GrgfZjfhdaxPXMsl2+o8jhp/hlIzG56taNdt VZtPp3ih1AgbR8rHgXw1xwOpuAd5lE1qNd54ndHuADO9a9A0vPimIes78Hi1/yy+ZEEvRkHk /kDa6F3AtTc1m4rbbOk2fiKzzsE9YXweFjQvl9p+AMw6qd/iC4lUk9g0+FQXNdRs+o4o6Qvy iOQJfGQ4UcBuOy1IrkJrd8qq5jet1fcM2j4QvsW8CLDWZS1L7kZ5gT5EycMKxUWb8LuRjxzZ 3QY1aQH2kkzn6acigU3HLtgFyV1gBNV44ehjgvJpRY2cC8VhanTx0dZ9mj1YKIky5N+C0f21 zvntBqcxV0+3p8MrxRRcgEtDZNav+xAoT3G0W4SahAaUTWXpsZoOecwtxi74CyneQNPTDjNg azHmvpdBVEfj7k3p4dmJp5i0U66Onmf6mMFpArvBRSMOKU9DlAzMi4IvhiNWjKVaIE2Se9BY FdKVAJaZq85P2y20ZBd08ILnKcj7XKZkLU5FkoA0udEBvQ0f9QLNyyy3DZMCQWcwRuj1m73D sq8DEFBdZ5eEkj1dCyx+t/ga6x2rHyc8Sl86oK1tvAkwBNsfKou3v+jP/l14a7DGBvrmlYjO 59o3t6inu6H7pt7OL6u6BQj7DoMAEQEAAcLBfAQYAQgAJgIbDBYhBBvZyq1zXEw6Rg38yk3e EPcA/4NaBQJonNqrBQkmWAihAAoJEE3eEPcA/4NaKtMQALAJ8PzprBEXbXcEXwDKQu+P/vts IfUb1UNMfMV76BicGa5NCZnJNQASDP/+bFg6O3gx5NbhHHPeaWz/VxlOmYHokHodOvtL0WCC 8A5PEP8tOk6029Z+J+xUcMrJClNVFpzVvOpb1lCbhjwAV465Hy+NUSbbUiRxdzNQtLtgZzOV Zw7jxUCs4UUZLQTCuBpFgb15bBxYZ/BL9MbzxPxvfUQIPbnzQMcqtpUs21CMK2PdfCh5c4gS sDci6D5/ZIBw94UQWmGpM/O1ilGXde2ZzzGYl64glmccD8e87OnEgKnH3FbnJnT4iJchtSvx yJNi1+t0+qDti4m88+/9IuPqCKb6Stl+s2dnLtJNrjXBGJtsQG/sRpqsJz5x1/2nPJSRMsx9 5YfqbdrJSOFXDzZ8/r82HgQEtUvlSXNaXCa95ez0UkOG7+bDm2b3s0XahBQeLVCH0mw3RAQg r7xDAYKIrAwfHHmMTnBQDPJwVqxJjVNr7yBic4yfzVWGCGNE4DnOW0vcIeoyhy9vnIa3w1uZ 3iyY2Nsd7JxfKu1PRhCGwXzRw5TlfEsoRI7V9A8isUCoqE2Dzh3FvYHVeX4Us+bRL/oqareJ CIFqgYMyvHj7Q06kTKmauOe4Nf0l0qEkIuIzfoLJ3qr5UyXc2hLtWyT9Ir+lYlX9efqh7mOY qIws/H2t In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 5/12/26 15:04, Breno Leitao wrote: > On Tue, May 12, 2026 at 10:17:00AM +0200, David Hildenbrand (Arm) wrote: >>> @@ -2348,6 +2348,7 @@ int memory_failure(unsigned long pfn, int flags) >>> unsigned long page_flags; >>> bool retry = true; >>> int hugetlb = 0; >>> + bool is_reserved; >>> >>> if (!sysctl_memory_failure_recovery) >>> panic("Memory failure on page %lx", pfn); >>> @@ -2411,6 +2412,18 @@ int memory_failure(unsigned long pfn, int flags) >>> * In fact it's dangerous to directly bump up page count from 0, >>> * that may make page_ref_freeze()/page_ref_unfreeze() mismatch. >>> */ >>> + /* >>> + * Pages with PG_reserved set are not currently managed by the >>> + * page allocator (memblock-reserved memory, driver reservations, >>> + * etc.), so classify them as kernel-owned for reporting. >>> + * >>> + * Sample the flag before get_hwpoison_page(): in the >>> + * MF_COUNT_INCREASED path, get_any_page() can drop the caller's >>> + * reference before returning -EIO, after which page->flags may >>> + * have been reset by the allocator. >>> + */ >>> + is_reserved = PageReserved(p); >>> + >>> res = get_hwpoison_page(p, flags); >>> if (!res) { >>> if (is_free_buddy_page(p)) { >>> @@ -2432,7 +2445,11 @@ int memory_failure(unsigned long pfn, int flags) >>> } >>> goto unlock_mutex; >>> } else if (res < 0) { >>> - res = action_result(pfn, MF_MSG_GET_HWPOISON, MF_IGNORED); >>> + if (is_reserved) >>> + res = action_result(pfn, MF_MSG_KERNEL, MF_IGNORED); >>> + else >>> + res = action_result(pfn, MF_MSG_GET_HWPOISON, >>> + MF_IGNORED); >>> goto unlock_mutex; >>> } >>> >>> >> >> It's a bit odd that we need this handling when we already have handling for >> reserved pages in error_states[]. >> >> HWPoisonHandlable() would always essentially reject PG_reserved pages. So >> __get_hwpoison_page() ... would always fail? Making >> get_hwpoison_page()->get_any_page() always fail? >> >> But then, we never call identify_page_state()? And never call me_kernel()? > > From what I read, it seems that error_states[0] = { reserved, reserved, MF_MSG_KERNEL, me_kernel } > has been effectively dead code on the hwpoison-from-MCE path for a > while. > > My v6 patch relabels the failure-path output to match what me_kernel() would > have reported anyway. > >> This all looks very odd. >> >> Why would you even want to call get_hwpoison_page() in the first place if you >> find PageReserved? > > Are you suggesting we should all the page action as soon as we detect the page > is reserved and get out? > > Something as: > > if (PageReserved(p)) { > res = action_result(pfn, MF_MSG_KERNEL, MF_IGNORED); > goto unlock_mutex; > } > > res = get_hwpoison_page(p, flags); Or you combine this patch with the other patch and let simply get_hwpoison_page() check that, and return an appropriate error code for unhandable that you can process here? Like, maybe, returning -EIO directly? res = get_hwpoison_page(p, flags); switch (res) { case 0: /* Success */ ... break case -EIO: /* Unhandable kernel page. */ ... break; case -EBUSY: /* Race, try again? */ ... break; case ... } You can add more return codes as you see fit. -- Cheers, David