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 CF837372057; Mon, 1 Jun 2026 13:22:22 +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=1780320144; cv=none; b=fm79VS2X+LquguZj4/UWV4bxvJizsTQre+Dp1EpQDv57T9MxP2WXb61KDP9MkJTT9TdZ963c9IGxmPlfyc6c+vknUMsI2idWJ4AZJLqL+W91qrH74fERMwAwws+24WI7k+YRnyxBa524d60ldIY/CPE3YZHf1vBUNuL9DuQyXA4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780320144; c=relaxed/simple; bh=5IO3E8xNHF91kis6t4ZlSQgt9FsTb8dYFvmANv7NBsw=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=I5/n9dHIXUUHKyxCpXvYhKJxUXVEtl/pvVKedFA6oC6QlRT393Lq/auro9dx1dHP2C1nG7PmjKex41ZVisZu/TT85rvVIAnkwxH05MEOZzcDI3aYXF83VhaAnC+ubvBILiRlTXa/w2RnHdJR6vKxU7/kOnXBGQDVMMVPjwxBwHs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=LU6AW3wK; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="LU6AW3wK" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4DBE31F00893; Mon, 1 Jun 2026 13:22:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1780320142; bh=WDT+8+ETf4Oj92XwVc++A5fr+CCglKoLUu0D8KimQ84=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=LU6AW3wKuu8SCk7DkUOYOGjAikqXBQEAcRgbGOhMTZuzzL/jEjz6W1NAmcd6J71nD f1J9yPoVcNbopDcXDC/tRcytt3DWozJFC9hp37ufoeat0oPOYbTnmMQuustGcQE3Jl PQ4S5jvRVPvXPa5T686eyp57lLX/9XOLhfmd+hvxtNThxOlIsz+ycJGq9VmnAeVdCa p53tUKhy7GipyNvMCP3/OESrPe2OjXaHKvEbJoFGg0onrA/I81UnFMddcqeSHXxXdK IWJiln4pvPHWl61ksfS3UuHn5NoD/Fb5Hyo1PX5J8sBDZjYxsOycLs822PbzqdfcIb 8USWAXGFgogGg== Message-ID: Date: Mon, 1 Jun 2026 15:22:15 +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 v8 2/6] mm/memory-failure: surface unhandlable kernel pages as -ENOTRECOVERABLE To: Miaohe Lin , Breno Leitao 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 , Andrew Morton , Lorenzo Stoakes , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Shuah Khan , Naoya Horiguchi , Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , Jonathan Corbet , Shuah Khan , "Liam R. Howlett" References: <20260527-ecc_panic-v8-0-9ea0cfa16bb0@debian.org> <20260527-ecc_panic-v8-2-9ea0cfa16bb0@debian.org> <19f968f5-1289-f573-4406-e5c91dcd8923@huawei.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: <19f968f5-1289-f573-4406-e5c91dcd8923@huawei.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 6/1/26 14:28, Miaohe Lin wrote: > On 2026/5/27 22:06, Breno Leitao wrote: >> get_any_page() collapses every HWPoisonHandlable() rejection into a >> single -EIO via the __get_hwpoison_page() -> -EBUSY -> shake_page() >> -> retry path. That is correct for the transient case (a userspace >> folio briefly off LRU during migration or compaction, which a later >> shake can drag back), but wrong for stable kernel-owned pages: slab, >> page-table, large-kmalloc and PG_reserved pages will never become >> HWPoisonHandlable(), so the retry loop is wasted work and the final >> -EIO loses the "this is structurally unrecoverable" information. >> memory_failure() then maps -EIO into MF_MSG_GET_HWPOISON, which the >> panic-on-unrecoverable sysctl deliberately does not act on. >> >> Introduce HWPoisonKernelOwned(), a small predicate that positively >> identifies pages the hwpoison handler cannot recover from: >> >> HWPoisonKernelOwned(p, flags) := >> !(MF_SOFT_OFFLINE && page_has_movable_ops(p)) && >> (PageReserved(p) || PageSlab(p) || >> PageTable(p) || PageLargeKmalloc(p)) >> >> The MF_SOFT_OFFLINE / page_has_movable_ops() opt-out mirrors the >> same exception in HWPoisonHandlable(): soft-offline is allowed to >> migrate movable_ops pages even though they are not on the LRU, and >> we must not pre-empt that with an unrecoverable verdict. >> >> The list is intentionally not exhaustive. vmalloc and kernel-stack >> pages, for example, do not carry a page_type bit and would need a >> different oracle; they keep going through the existing retry path >> unchanged. This is the smallest set we can identify with certainty >> by page type. >> >> Wire the helper into the top of get_any_page() to short-circuit >> those pages before the retry loop runs. On a hit, drop the caller's >> MF_COUNT_INCREASED reference (if any) and return -ENOTRECOVERABLE >> straight away. Pages outside the helper's positive list still take >> the existing retry path and return -EIO, leaving operator-visible >> behaviour for those cases unchanged. >> >> Extend the unhandlable-page pr_err() to fire for either errno and >> update the get_hwpoison_page() kerneldoc to document the new return. >> >> memory_failure() still folds every negative return into >> MF_MSG_GET_HWPOISON via its existing "else if (res < 0)" branch, so >> this patch on its own only changes the errno that soft_offline_page() >> can propagate to its callers. A follow-up wires -ENOTRECOVERABLE >> through memory_failure() and reports MF_MSG_KERNEL for the >> unrecoverable cases, which is what the >> panic_on_unrecoverable_memory_failure sysctl observes. > > Thanks for your patch. > >> >> Suggested-by: David Hildenbrand >> Suggested-by: Lance Yang >> Signed-off-by: Breno Leitao >> --- >> mm/memory-failure.c | 42 ++++++++++++++++++++++++++++++++++++++++-- >> 1 file changed, 40 insertions(+), 2 deletions(-) >> >> diff --git a/mm/memory-failure.c b/mm/memory-failure.c >> index f4d3e6e20e13..8f63bdfeff8f 100644 >> --- a/mm/memory-failure.c >> +++ b/mm/memory-failure.c >> @@ -1325,6 +1325,28 @@ static inline bool HWPoisonHandlable(struct page *page, unsigned long flags) >> return PageLRU(page) || is_free_buddy_page(page); >> } >> >> +/* >> + * Positive identification of pages the hwpoison handler cannot recover. >> + * These page types are owned by kernel internals (no userspace mapping >> + * to unmap, no file mapping to invalidate, no migration target), so the >> + * shake_page() / retry loop in get_any_page() can never turn them into >> + * something HWPoisonHandlable() will accept. Short-circuit them to >> + * -ENOTRECOVERABLE so callers can panic on operator request instead of >> + * spinning through retries that exit as a transient-looking -EIO. >> + * >> + * The MF_SOFT_OFFLINE / page_has_movable_ops() opt-out mirrors >> + * HWPoisonHandlable(): soft-offline is allowed to migrate movable_ops >> + * pages even though they are not on the LRU. >> + */ >> +static inline bool HWPoisonKernelOwned(struct page *page, unsigned long flags) >> +{ >> + if ((flags & MF_SOFT_OFFLINE) && page_has_movable_ops(page)) >> + return false; >> + >> + return PageReserved(page) || PageSlab(page) || > > Once shake_page finds a lightweight range-based way to shrink slab, slab pages could be freed > into buddy and above PageSlab test should be removed then. Maybe add a TODO or XXX here? > >> + PageTable(page) || PageLargeKmalloc(page); > > I'm not sure but is it safe or a common way to test PageReserved, PageSlab, > PageTable and PageLargeKmalloc without extra page refcnt? Checking typed pages in a racy fashion is fine (PageSlab, PageTable, PageLargeKmalloc). Checking PageReserved in a racy fashion is fine as well. TESTPAGEFLAG() will allow checking it on compound pages. For PageLargeKmalloc, we would want to check the head page, though. The page type is only stored for the head page. So maybe we want to lookup the compound head (if any) and perform the type checks against that? -- Cheers, David