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 8D4E03D6CAF; Wed, 13 May 2026 07:54:07 +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=1778658847; cv=none; b=gIDSiJFSV7+JxH9teeEnZKRlcGTseZ2hNnT0IGlRkEOhj4VcANN0w80oM4/3s7q1hftAASSB8qTeOc38sGr37bKK29fMv7+6mhkyPdz7Uxl9cjgUoMK0njhdVbJ3AZRg31l4N02qsG0soaKhsqp5G9Et15Sginv4XRDUZQOXgPg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778658847; c=relaxed/simple; bh=jEoZFc6hihS2474unqKVMfhx3OcP9JIIwFxYzBVkiBo=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=MEdreieqbpatj/yXqG/4kmsiDTYcFb5gbFc+KBIwFad2FqwqJFzWwm6l3LEfBieZwOmVDoqzzmjc+smjoQhzb54rBzIT0iOuXBHDgHd+YAeqTSS66UcRQJ42GVGAhOcggGhzqPtqM4zDKetkudzOwR+WsIX+6qjhzzYRv0bdHGk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=PYL6rpKY; 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="PYL6rpKY" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DBEE9C2BCB7; Wed, 13 May 2026 07:53:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1778658847; bh=jEoZFc6hihS2474unqKVMfhx3OcP9JIIwFxYzBVkiBo=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=PYL6rpKYUiXu1R0TCAHtdQPhjDqrJb1rIK3Zcv8WsDoi4TN4S1aGc6a1lMRhXA7QR D8ZnVBGn1z5pboDVa50v5qRRzoxdxjc8gcIhVQI0fwk9OPCf+pjqeSGGdAlWKCCU5V eGj8XHtFbc0mN2LozqfaSGLj9DJV8dqdq66m5eIO7S+eD6McfYYBcoyr3fAItnYUlU 7uQjfZuetNc2/6CgE3XSJj0xLC+rmdYM1F8d2u+LUGC1sqw0ofk3cBKuIXyNsIr+YT 2AxtFw2eHlhnOWKl6uu2jfXqaxcEohqFOkH1+S2NWFjXGKgsFkOR538o+51YZlg76n ecRNSvw0Gh5wQ== Message-ID: Date: Wed, 13 May 2026 09:53:58 +0200 Precedence: bulk X-Mailing-List: linux-doc@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: jane.chu@oracle.com, Breno Leitao , 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" Cc: 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> <816e3d8e-22d2-49a4-92ae-981568f38792@oracle.com> 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: <816e3d8e-22d2-49a4-92ae-981568f38792@oracle.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 5/12/26 19:58, jane.chu@oracle.com wrote: > > > On 5/12/2026 1:17 AM, David Hildenbrand (Arm) wrote: >> On 5/11/26 17:38, Breno Leitao wrote: >>> When get_hwpoison_page() returns a negative value, distinguish >>> reserved pages from other failure cases by reporting MF_MSG_KERNEL >>> instead of MF_MSG_GET_HWPOISON. Reserved pages belong to the kernel >>> and should be classified accordingly for proper handling. >>> >>> Sample PG_reserved before the get_hwpoison_page() call. In the >>> MF_COUNT_INCREASED path get_any_page() can drop the caller's >>> reference before returning -EIO, after which the underlying page may >>> have been freed and reallocated with page->flags reset; reading >>> PageReserved(p) at that point would observe stale or unrelated state. >>> The pre-call snapshot reflects what the page actually was at the >>> time of the failure event. >>> >>> Acked-by: Miaohe Lin >>> Reviewed-by: Lance Yang >>> Signed-off-by: Breno Leitao >>> --- >>>   mm/memory-failure.c | 19 ++++++++++++++++++- >>>   1 file changed, 18 insertions(+), 1 deletion(-) >>> >>> diff --git a/mm/memory-failure.c b/mm/memory-failure.c >>> index 866c4428ac7ef..f112fb27a8ff6 100644 >>> --- a/mm/memory-failure.c >>> +++ b/mm/memory-failure.c >>> @@ -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()? >> >> This all looks very odd. >> >> Why would you even want to call get_hwpoison_page() in the first place if you >> find PageReserved? >> > > Ah, good point! > It seems to me that all unhandable pages should head out to identify_page_state: > > --- a/mm/memory-failure.c > +++ b/mm/memory-failure.c > @@ -2411,6 +2411,10 @@ 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. >          */ > + > +       if (!HWPoisonHandlable(page, flags) > +               goto identify_page_state; > + >         res = get_hwpoison_page(p, flags); >         if (!res) { >                 if (is_free_buddy_page(p)) { That's one option, or we just let get_hwpoison_page() return clearer error codes, let it take care of checking PageReserved, and process the error codes return by get_hwpoison_page() in a better way. -- Cheers, David