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 86C582F7445 for ; Thu, 6 Aug 2026 10:50:28 +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=1786013429; cv=none; b=Lryb28L48D6tvCiNvwN2P/NceC56ICS3RFRr/HNc3tU4MEjBuHMUmRSQ2FZAkNhEWmZz89kQBBSZRbQpKFplvU3gsjtDy7f+jUqsGFhpZaZBTGtiaZfMsiBprQxOErri75wahIw9HnrCZWT8u9BbPB8mc8A+XUeHZQo5gWjRtfQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786013429; c=relaxed/simple; bh=p7WAeC4YhHm17ywsWSph2lKY957RJVCFqP0L0cnHaBg=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=TKa+lUCAsrEh8e4x2UI7iR3awmps3rWH16doIV3+mOfdSmv0CmvnZYpcedFvadotxsyQb/+FmcWGK/zIKt9fY0Ap719SlebGbMuOEvsBbIEkxHG9hvWkIHKorvM43MAkMqyJ8Sa9a6IwLMty4hA3ufuloYuIorjD8LOJ8Dn3byA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=VPZtuL5j; 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="VPZtuL5j" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E29C61F000E9; Thu, 6 Aug 2026 10:50:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1786013428; bh=N6aH3IWhBuvYtU3jyYyQ38Aa7k9zKxtJGVyR123XyKk=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=VPZtuL5j3tQOtekLQ7kOVDseIfHGH5e5b4IjDJWQWyfGuDyEHmFasxyAg4Znie6lF Cs5dkDB0jrbs5MFYwQbm3F0UpK684wLeGJ7s5CBFVSq1wSeXFnA6k+Gl+G7xtVmHun 2nxsLiVNyOsVv6jTwOohQOSd93cii87KioJLnuYwBjdKmHrHNj2AxORBcj0LwPbJsm cVmcA+2urdOJJjPIRDLgo5mMvdKgnkUy9gsWSXaNXDRIzBytPEeDhllvcYEjBy611V 4q+gzfRRr48ZCgjM3YHpKL8eEX43RKoz0P7AIhh5YOvIiXN531OhTGkvlkcG2aABiv QVLJhIVXZdzow== Message-ID: <0726ba54-a500-46a4-b42f-3e581da0f070@kernel.org> Date: Thu, 6 Aug 2026 12:50:23 +0200 Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4] mm/memory-failure: fix folio refcount leak and locking in soft/hard offline To: Andrew Morton , dayou5941@163.com Cc: linmiaohe@huawei.com, ljs@kernel.org, nao.horiguchi@gmail.com, linux-mm@kvack.org, ziy@nvidia.com, Li Youhong , Sashiko , stable@vger.kernel.org References: <20260806031958.677935-1-dayou5941@163.com> <20260805213415.002dc67766271d21c232910b@linux-foundation.org> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 8bit On 8/6/26 06:34, Andrew Morton wrote: > On Thu, 6 Aug 2026 11:19:58 +0800 dayou5941@163.com wrote: > >> From: Li Youhong >> >> The min_order_for_split() function accesses folio->mapping without proper >> synchronization. In memory_failure(), the folio lock is dropped before the >> call, and in soft_offline_in_use_page(), the lock is not held at all. This >> means that while min_order_for_split() is executing, the value of >> folio->mapping may be modified by a truncate or invalidate operation, >> leading to a torn read or use of a stale mapping value. >> >> Additionally, the soft_offline_in_use_page() path fails to release the >> folio reference taken by get_hwpoison_page() when new_order != 0, causing a >> reference leak. >> >> Fix these issues by: >> - Moving the split operation logic into the callers and holding the folio >> lock around min_order_for_split() and split_huge_page_to_order(). >> - Removing the try_to_split_thp_page() helper to simplify refcount >> handling. >> - Ensuring the folio reference is always dropped before returning on the >> soft-offline error path. >> >> This refactors the code to be more maintainable, fixes the locking issue >> reported by Sashiko, and also addresses the folio reference leak on the >> soft-offline error path. >> >> ... >> >> --- a/mm/memory-failure.c >> +++ b/mm/memory-failure.c >> static void unmap_and_kill(struct list_head *to_kill, unsigned long pfn, >> struct address_space *mapping, pgoff_t index, int flags) >> { >> @@ -2440,7 +2420,6 @@ int memory_failure(unsigned long pfn, int flags) >> folio_unlock(folio); >> >> if (folio_test_large(folio)) { >> - const int new_order = min_order_for_split(folio); >> int err; >> >> /* >> @@ -2457,24 +2436,24 @@ int memory_failure(unsigned long pfn, int flags) >> * page is a valid handlable page. >> */ >> folio_set_has_hwpoisoned(folio); >> - err = try_to_split_thp_page(p, new_order, /* release= */ false); > > AI review asks (effectively) why the try_to_split_thp_page() return value > never gets used > > https://sashiko.dev/#/patchset/20260806031958.677935-1-dayou5941@163.com > No need for AI. Just from compiling: └ mm/memory-failure.c: In function ‘memory_failure’: mm/memory-failure.c:2492:21: warning: variable ‘err’ set but not used [-Wunused-but-set-variable] 2492 | int err; I'll send out a patch myself that already addresses everything raised in here without even me reading any of it. -- Cheers, David