From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id C397CCD8CAD for ; Tue, 9 Jun 2026 18:41:37 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 37CD96B0093; Tue, 9 Jun 2026 14:41:37 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 3547A6B0095; Tue, 9 Jun 2026 14:41:37 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 26A9F6B0096; Tue, 9 Jun 2026 14:41:37 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id 168216B0093 for ; Tue, 9 Jun 2026 14:41:37 -0400 (EDT) Received: from smtpin21.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay10.hostedemail.com (Postfix) with ESMTP id D2D4BC26C5 for ; Tue, 9 Jun 2026 18:41:36 +0000 (UTC) X-FDA: 84861242592.21.E5A88A4 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf25.hostedemail.com (Postfix) with ESMTP id 1291EA0016 for ; Tue, 9 Jun 2026 18:41:34 +0000 (UTC) Authentication-Results: imf25.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b="n/s/LF6J"; spf=pass (imf25.hostedemail.com: domain of david@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1781030495; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=rRqUAdkAgr6Ypp8Su6+2n5PtsOSqMs20GrK0aAXdiU0=; b=i6dpP/2IDmW/snZ6+sU5FXCKugprJoKgDYQVthvtXQt3dmvUAqvUirfBGBiCNvD4jCRtAm WGxeG1jyxFjps1XeBQawulhtDLI5/ritBfFEJI+Z+BBVnDQcJpF5qthq5hRxtVAX6tIdfu l7wx0giuvOSGLTXM1FaTBTPuc8OPPMc= ARC-Authentication-Results: i=1; imf25.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b="n/s/LF6J"; spf=pass (imf25.hostedemail.com: domain of david@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1781030495; b=4G4E8R1BqiJiDwN5qVUb/bs6uOxQ+vcd14ytBH4Qa/Zh6O+lPsGqh5h2XpiH8Sfu3Vfruu Ms6+mjta5Q36kNyIxUtfpJdEVRKUrrp/a+C7aSWhYd+eHsRQaeEIRDgXQa5Us4w2PAHTtD B8nH5KpkqrTNpcM4eKo3+kb48ED0GDU= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 7D0E86024D; Tue, 9 Jun 2026 18:41:34 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A02BC1F00893; Tue, 9 Jun 2026 18:41:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1781030494; bh=rRqUAdkAgr6Ypp8Su6+2n5PtsOSqMs20GrK0aAXdiU0=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=n/s/LF6JEqwIWKt9Q7XElB33dDXdgS/LPOJVRmRcwWm5MAB6i2lkrwfbAhA0gfTx+ 59NfwWG2KwBDmUOV6bsAfxSArZcFcKV/SvaBUmia5LCaZ2W7892C52u+Z++06W3dCi C6/ZSHM+j2i3qfGcqTHnuo0H3xgWvHlFCel0FC0751zl6BUXxf8XZ3j5MpyPEp6p9I zwFfXxt2Z03iYrdd+7P/RBEy/Qe1jPd2NSesyYWhKUw9wu1wMX3EAziFf4gQ/LvBPk 35cWOxTQwJ7vG4cyGBIvJewYSa968HRt1WkEKYwHe420u5TmWsPPFerMxQRedNug1m CrKWll7YTrRgw== Message-ID: Date: Tue, 9 Jun 2026 20:41:25 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v9 2/6] mm/memory-failure: surface unhandlable kernel pages as -ENOTRECOVERABLE To: Breno Leitao Cc: Miaohe Lin , Andrew Morton , Lorenzo Stoakes , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Shuah Khan , Naoya Horiguchi , Jonathan Corbet , Shuah Khan , "Liam R. Howlett" , lance.yang@linux.dev, Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , 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 References: <20260609-ecc_panic-v9-0-432a74002e74@debian.org> <20260609-ecc_panic-v9-2-432a74002e74@debian.org> <174b8d76-5514-4942-af5d-c975ff95ee03@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 X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 1291EA0016 X-Stat-Signature: tpaofzb61qfzqbsgcc3nyyf39mpaqysu X-Rspam-User: X-HE-Tag: 1781030494-692268 X-HE-Meta: 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 WX5Rp/+c zaOQoXoceTHm2n0TOq8sNGweCMMtSWF+h1Fp9/AwnlEmisgtQbmiw3jnmptQWFBoOOC/KFN8+e8of5cPH/CeT8v3pHo+AgfonxJE2IWls3F8BbTzTOsVQdTUHQnn+Yw/FUVl8cq76h8fDveyiRzYK4Tglydcmg13OWoeJbI2VsBMF3mziHJtsCEU++CAmXqTyNJloK+0q7ror0Aoi+2rHCTMvhMNi5/HJ3EnLWyHyuDyLjB3CUNTml/8G7r5a7O/pzYwuCH9vn59luOfGDJa5vLpnaAPYoeu3j6UPZeAmK/LyCzRJ6aAmqexYbvrkazr7nrEA7iiaIm+BXCvgZKozgIXalrKC+JlBDiwn9KoI/pKVf7tuli28CF0jMa7F3kcRNoDG Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 6/9/26 18:15, Breno Leitao wrote: > On Tue, Jun 09, 2026 at 04:41:01PM +0200, David Hildenbrand (Arm) wrote: >> On 6/9/26 12:56, 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(head) || PageTable(head) || PageLargeKmalloc(head)) >>> >>> where head = compound_head(p). >>> >>> PG_reserved is a per-page flag (PF_NO_COMPOUND) and is tested on the >>> page directly. The slab, page-table and large-kmalloc page-type bits >>> are only stored on the head page, so those tests resolve the compound >>> head first, then re-read compound_head(page) afterwards: a concurrent >>> split or compound free that moves head invalidates the just-read flags >>> and the loop retries. The lookup still takes no refcount, mirroring >>> the rest of get_any_page(); the recheck closes the common split race, >>> and a residual free->alloc->free in the same window can only mis-tag >>> a genuinely poisoned page, never reclassify a handlable one. >>> >>> 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. >>> >>> Suggested-by: David Hildenbrand >>> Suggested-by: Lance Yang >>> Signed-off-by: Breno Leitao >>> --- >>> mm/memory-failure.c | 60 +++++++++++++++++++++++++++++++++++++++++++++++++++-- >>> 1 file changed, 58 insertions(+), 2 deletions(-) >>> >>> diff --git a/mm/memory-failure.c b/mm/memory-failure.c >>> index f4d3e6e20e13..eed9de387694 100644 >>> --- a/mm/memory-failure.c >>> +++ b/mm/memory-failure.c >>> @@ -1325,6 +1325,46 @@ 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) >>> +{ >>> + struct page *head; >>> + >>> + if ((flags & MF_SOFT_OFFLINE) && page_has_movable_ops(page)) >>> + return false; >>> + >> >> On a second look: Do we really need that? The page types below never support >> migration. So I guess that check is not required? >> >> Apart from that, looks good with two comments: >> >> a) HWPoisonKernelOwned: this is not the common style for us to name functions. >> >> is_kernel_owned_page() or sth like that would do. > > Ack, I will rename it is_kernel_owned_page() > > In my defence, most of the functions similar to HWPoisonKernelOwned() > has this name format, and I got this discussion earlier (with Lance? > I think). Here are the similar function names in that file: > > * HWPoisonHandlable > * PageHWPoisonTakenOff() > * SetPageHWPoisonTakenOff Some of these probably date back to our old way of handling page flags and things, like PageLRU. But we really should stop :) > > I will update in the new version. Thanks! Probably best to wait a bit, the merge window is coming up either way, so this will have to wait a bit either way. -- Cheers, David