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 CBF5D54763; Fri, 21 Nov 2025 13:22:41 +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=1763731361; cv=none; b=Gl++ZYD1I2eOPnwskQzyxR2LoRP2c+auYu7D4UOAYXxdmAAs+AweXfmkVbg71NmoA5urmwTmo9082XP3dE1AfFhSISqfL46QrIAhZ7tbBl8l1QiM/RIzpI4EJNk3t5pNwJ7O+/lKYiEEAqQGyAW4NpG5w7JoA1nlF8jFZPPHRq4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763731361; c=relaxed/simple; bh=Y4/fPPodj75Iuv7whpf7nwnZVs/z74V/u9mhFYt6c+g=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=MNDwKJ6+uqfmFklA4P31ym4MQ3HtpJTDghk1W6BOlKCeiMFyh9tn6kS8Yvc6vqkjQVAg6+QST5zkoOzcJql6DSY7OfyWpaXwLniHaKOVfeZ3OeUXJQAwZqvJD5/YSdpPBmA2615KMwQRa4FQuY0nJrKEZvj/MevbqLMf7gLy9Zw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=hcGaTwHK; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="hcGaTwHK" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 23565C4CEF1; Fri, 21 Nov 2025 13:22:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1763731361; bh=Y4/fPPodj75Iuv7whpf7nwnZVs/z74V/u9mhFYt6c+g=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=hcGaTwHKH9pk/O69WIt8OZK80jms4HeRszpP1ESd3lae2P3iIVSM2MpsSB+IgrJlw ifPX2nA4Ai4K4bVqN5hMxwiPVMstfLbH7lHYUCCMOLrvzNqnfxG2mZ8d1khAt+LhfV MXbpxPWKYUEQ8BATJuXrCrZA70BUGgY+A5Ns9hvI= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Zi Yan , David Hildenbrand , Yang Shi , Lorenzo Stoakes , Lance Yang , Miaohe Lin , Baolin Wang , Wei Yang , Pankaj Raghav , Barry Song , Dev Jain , Jane Chu , Liam Howlett , Luis Chamberalin , "Matthew Wilcox (Oracle)" , Naoya Horiguchi , Nico Pache , Ryan Roberts , Andrew Morton Subject: [PATCH 6.17 181/247] mm/huge_memory: preserve PG_has_hwpoisoned if a folio is split to >0 order Date: Fri, 21 Nov 2025 14:12:08 +0100 Message-ID: <20251121130201.219084291@linuxfoundation.org> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20251121130154.587656062@linuxfoundation.org> References: <20251121130154.587656062@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.17-stable review patch. If anyone has any objections, please let me know. ------------------ From: Zi Yan commit fa5a061700364bc28ee1cb1095372f8033645dcb upstream. folio split clears PG_has_hwpoisoned, but the flag should be preserved in after-split folios containing pages with PG_hwpoisoned flag if the folio is split to >0 order folios. Scan all pages in a to-be-split folio to determine which after-split folios need the flag. An alternatives is to change PG_has_hwpoisoned to PG_maybe_hwpoisoned to avoid the scan and set it on all after-split folios, but resulting false positive has undesirable negative impact. To remove false positive, caller of folio_test_has_hwpoisoned() and folio_contain_hwpoisoned_page() needs to do the scan. That might be causing a hassle for current and future callers and more costly than doing the scan in the split code. More details are discussed in [1]. This issue can be exposed via: 1. splitting a has_hwpoisoned folio to >0 order from debugfs interface; 2. truncating part of a has_hwpoisoned folio in truncate_inode_partial_folio(). And later accesses to a hwpoisoned page could be possible due to the missing has_hwpoisoned folio flag. This will lead to MCE errors. Link: https://lore.kernel.org/all/CAHbLzkoOZm0PXxE9qwtF4gKR=cpRXrSrJ9V9Pm2DJexs985q4g@mail.gmail.com/ [1] Link: https://lkml.kernel.org/r/20251023030521.473097-1-ziy@nvidia.com Fixes: c010d47f107f ("mm: thp: split huge page to any lower order pages") Signed-off-by: Zi Yan Acked-by: David Hildenbrand Reviewed-by: Yang Shi Reviewed-by: Lorenzo Stoakes Reviewed-by: Lance Yang Reviewed-by: Miaohe Lin Reviewed-by: Baolin Wang Reviewed-by: Wei Yang Cc: Pankaj Raghav Cc: Barry Song Cc: Dev Jain Cc: Jane Chu Cc: Liam Howlett Cc: Luis Chamberalin Cc: Matthew Wilcox (Oracle) Cc: Naoya Horiguchi Cc: Nico Pache Cc: Ryan Roberts Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman --- mm/huge_memory.c | 23 ++++++++++++++++++++--- 1 file changed, 20 insertions(+), 3 deletions(-) --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -3271,6 +3271,14 @@ bool can_split_folio(struct folio *folio caller_pins; } +static bool page_range_has_hwpoisoned(struct page *page, long nr_pages) +{ + for (; nr_pages; page++, nr_pages--) + if (PageHWPoison(page)) + return true; + return false; +} + /* * It splits @folio into @new_order folios and copies the @folio metadata to * all the resulting folios. @@ -3278,17 +3286,24 @@ bool can_split_folio(struct folio *folio static void __split_folio_to_order(struct folio *folio, int old_order, int new_order) { + /* Scan poisoned pages when split a poisoned folio to large folios */ + const bool handle_hwpoison = folio_test_has_hwpoisoned(folio) && new_order; long new_nr_pages = 1 << new_order; long nr_pages = 1 << old_order; long i; + folio_clear_has_hwpoisoned(folio); + + /* Check first new_nr_pages since the loop below skips them */ + if (handle_hwpoison && + page_range_has_hwpoisoned(folio_page(folio, 0), new_nr_pages)) + folio_set_has_hwpoisoned(folio); /* * Skip the first new_nr_pages, since the new folio from them have all * the flags from the original folio. */ for (i = new_nr_pages; i < nr_pages; i += new_nr_pages) { struct page *new_head = &folio->page + i; - /* * Careful: new_folio is not a "real" folio before we cleared PageTail. * Don't pass it around before clear_compound_head(). @@ -3330,6 +3345,10 @@ static void __split_folio_to_order(struc (1L << PG_dirty) | LRU_GEN_MASK | LRU_REFS_MASK)); + if (handle_hwpoison && + page_range_has_hwpoisoned(new_head, new_nr_pages)) + folio_set_has_hwpoisoned(new_folio); + new_folio->mapping = folio->mapping; new_folio->index = folio->index + i; @@ -3430,8 +3449,6 @@ static int __split_unmapped_folio(struct if (folio_test_anon(folio)) mod_mthp_stat(order, MTHP_STAT_NR_ANON, -1); - folio_clear_has_hwpoisoned(folio); - /* * split to new_order one order at a time. For uniform split, * folio is split to new_order directly.