From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794046779; b=gs8VtoRAOu1xYNlyWf5Zdwu1myHkWnJAcnN/8grwqZ1/7H0E5vRLoL8va0gYzy5Aru5j AD/AwpeK1mN0Bq+adD6xeFwKmWz9XuTAsefZSad1WIS3GE+ZnId4fwTr/DO0LRS1jlUXa OOUvCheTnAg/8kCFBAvEo1KTnxzUXNbzf71HxGC80qUK7K+xgPRC0n4biWfmCid0GzTRE xZ1Qx8Vv990fzQyJz6Sm79nhq1HQ4vtTGUidJsFYkygToQWu9x5MG53s6zpY4uJ9QdlJ6 6Uof79EPZw2Bvp8G54BhyFHlA1tXhhhY9mmghfUtPt035On1/hxZQB4Nj3S5GxAA7IA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794046779; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=EYSkzzHYXIb41OWKWJV6qauHH3/LH4Y6zZlc08hrLU0=; b=j41d2JizXAdcwf/SLgljTp61VrKXfdGkjfpO6S542V5w4Jal7n1JNjY70T5ztv8E0XZT xNTfjZR3RnNyfCFmX1NTOf/ZUBEROXLx99flBs5QFtivjcxfg2PDpHLbCwNk4UxvQBQ79 sxM7Y6sFJEKXcXOMc/An1MwpUcXlmcXS5ZKcwFPuz22DunWeklHuld3EBd9HtqMl/C3UI +SB/5HJ/XoVuWLf+dbPmHN8ILe/SPz6W5uxk1P/4NzuUlpSl/JgxLQGJCL/48HeHdLZMH D+DGFuUhMXmpiMrbAvyhSzO2JsLwxL1qLQ8igxZZtZucwIsJLm9nly3Z4tVUuwRtslA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=AplRwNIv; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A0460606D804 for ; Sat, 7 Nov 2026 10:19:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=AplRwNIv Received: by smtp.kernel.org (Postfix) with ESMTPSA id 975AE1F0089F; Sat, 7 Nov 2026 10:19:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794046778; bh=EYSkzzHYXIb41OWKWJV6qauHH3/LH4Y6zZlc08hrLU0=; h=From:To:Cc:Subject:Date; b=AplRwNIvYSNY8zTkFNmykhvyOjhDeID5o7ZrRNztQDSyg2CJRm3rg2dLwcQnfOyv+ pv128PjsPhRriNy/Ll6v2Ptd3H69olwqUmr86svmykgQziLIGmwezsy275BpJsTtYR 0oO1hlTRvZmSeFBbh2FitiSGJnTJIkIclVW2HntJJmDfyyFbpOU94/4arfxebUH7nh hrPYbElx+iifgtGaGlNhKkcgN6AQLCYeDTfNXMswIQpcEocTU5HCKQY2jwCdySUgjF rzwX4TiqXuQtqeBUpESrA36dy6V6/1RIOh/eZz19AQ7odGTNkwyaJMMKBD4/XV+5oe tseOS5UeqXbpw== From: Sasha Levin To: roxy520tt@gmail.com, enjou1224z@gmail.com, akpm@linux-foundation.org, vega@nebusec.ai, liuye@kylinos.cn Cc: stable@vger.kernel.org Subject: FAILED: patch "[PATCH] mm/page_table_check: skip zero pages" failed to apply to 6.12-stable tree Date: Sat, 7 Nov 2026 05:19:36 -0500 Message-ID: <20261107051936-failed-6.12-33afd07412a1@kernel.org> X-Mailer: git-send-email 2.53.0 X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The patch below does not apply to the 6.12-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.12.y git checkout FETCH_HEAD git cherry-pick -x 33afd07412a1efe5b750a3fd5eb0272ebdd12761 # git commit -s git send-email --to '' --in-reply-to '20261107051936-failed-6.12-33afd07412a1@kernel.org' --subject-prefix 'PATCH 6.12.y' 'HEAD^..' Thanks, Sasha ------------------ original commit in Linus's tree ------------------ >From 33afd07412a1efe5b750a3fd5eb0272ebdd12761 Mon Sep 17 00:00:00 2001 From: Zhiling Zou Date: Tue, 21 Jul 2026 23:56:38 +0800 Subject: [PATCH] mm/page_table_check: skip zero pages page_table_check_set() accounts pages by whether they are PageAnon(). The shared zero page is a special page, not an ordinary file-backed page. Read faults on private anonymous mappings can install many read-only PTEs that point at the zero page, but page_table_check currently accounts them in file_map_count. That lets an unprivileged process populate enough zero-page mappings to overflow file_map_count and trip the BUG_ON() in page_table_check_set(). Skip zero pages in page_table_check accounting. They do not need the anonymous/file mapping conflict checks that page_table_check performs for ordinary pages, and this keeps the existing counter size and page_ext layout unchanged. Link: https://lore.kernel.org/1f8848512d2e3ded944f8d595c29faee8fdaeab0.1784645969.git.roxy520tt@gmail.com Fixes: df4e817b7108 ("mm: page table check") Signed-off-by: Zhiling Zou Signed-off-by: Ren Wei Signed-off-by: Andrew Morton Reported-by: Vega Assisted-by: Codex:gpt-5.4 Cc: Ye Liu Cc: --- mm/page_table_check.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/mm/page_table_check.c b/mm/page_table_check.c index ed3e1a76f2664..143a918c0bde2 100644 --- a/mm/page_table_check.c +++ b/mm/page_table_check.c @@ -67,7 +67,7 @@ static void page_table_check_clear(unsigned long pfn, unsigned long pgcnt) struct page *page; bool anon; - if (!pfn_valid(pfn)) + if (!pfn_valid(pfn) || is_zero_pfn(pfn) || is_huge_zero_pfn(pfn)) return; page = pfn_to_page(pfn); @@ -102,7 +102,7 @@ static void page_table_check_set(unsigned long pfn, unsigned long pgcnt, struct page *page; bool anon; - if (!pfn_valid(pfn)) + if (!pfn_valid(pfn) || is_zero_pfn(pfn) || is_huge_zero_pfn(pfn)) return; page = pfn_to_page(pfn); -- 2.53.0