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 143A93839B6; Wed, 13 May 2026 07:54:27 +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=1778658868; cv=none; b=fRA9XsKj9lTCTXDcGH1NP5ztqWYeXRjVuTfchfElMCt1HZlcINFO5wH0hWwkBCbtKCc3mGdmK6Gfw6fFgNqTU7gXk9yeetfmZHXq463ZimQpkrN+so/xJB7SiUBjwdz7DSPqSefqzwmPG/g8nLhIGb8JweAaU3IUxdVcDwPdPBU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778658868; c=relaxed/simple; bh=5fkTxaVzV67Mp0x6THoCadQuwmPOJZaYcb+VcvMagmI=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=Yu4ZxLAU4wUMjvyvMAarjXSVeMxLDYrvJER0pngXMKXAAOfr1cSDUoIdoRLTRNkC21eelgni42f+lIs7nNUI+o9ql3Pl4ATGFBs/YHAxXI49nPOkiU/rmZSFGCCthK3fXaB9gOBT8Q8TXqn6j2Hwf5oOx1rtUZC56iydhjsbi0k= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=MMSb57Ve; 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="MMSb57Ve" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 399DCC2BCB7; Wed, 13 May 2026 07:54:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1778658867; bh=5fkTxaVzV67Mp0x6THoCadQuwmPOJZaYcb+VcvMagmI=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=MMSb57VeWOdXEwlbRHF4H1wJyw7LzX8e2zt39PI2tcH5khVQ/JKO0bzfWh+hgHTy/ /f2AnrsyQvgXBfNReRpAvGpe7P6Iba3WDMzdxgabnfwgwWqOfYq+QeuCIKIfw82yOZ SbpoH+qAjPOALH5Pu5Begy9Whtf2B9RzbCSoXxxHUdwiAt1hZ8nNx8SZvbZDGghdqJ 9uEGk97TUCdjSh/lbRaAMjoMNm36B01uDz7I8kCrAdiclBC0uoNDwJM9+YvC76Z/p/ 6Zt4xHhoLHShLkd9bbEK0Un+0sxAF9MWduSGYLr2P7a9Eqen3WyM5qcjEXaL0L/eu+ OyDj4h0l+avrg== Message-ID: Date: Wed, 13 May 2026 09:54:19 +0200 Precedence: bulk X-Mailing-List: linux-trace-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: Lance Yang Cc: leitao@debian.org, linmiaohe@huawei.com, nao.horiguchi@gmail.com, akpm@linux-foundation.org, corbet@lwn.net, skhan@linuxfoundation.org, ljs@kernel.org, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, shuah@kernel.org, rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, liam@infradead.org, 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: <9504c193-8c01-4d03-8f62-c50fd7fbdbc0@kernel.org> <20260512124837.38883-1-lance.yang@linux.dev> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 5/12/26 14:48, Lance Yang wrote: > > On Tue, May 12, 2026 at 10:17:00AM +0200, 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()? > > Looks like we never get that far ... Right, likely that should be removed+cleaned up then. -- Cheers, David