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 47C5B18C034; Thu, 17 Apr 2025 18:57:14 +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=1744916234; cv=none; b=ZkSucB1iW3BV5tfsYiPnNavB3kB5wDM391rVXJc6rwhZ2R0BOJwvYX0CnmcaeqazUItrbTLCIFKTMUmnU9FVV/oH0SImOTJNySopWLMQrsE47NX9UV6iwtiZXXuVlXGuG5Sf2gWu88DrCa71XtBkDru4i8vn7629cBZscL9GEjc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744916234; c=relaxed/simple; bh=Rf/PKusgWEe9f1n47I8d3vI/e4IorQVrj1aO3ii29Hg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=lgTBh0NHsiYcpfls8CHebSSzHWmzDrkrAXaj7YGLClzfJISFWBrhPN/+xZkJuXfe2T8XRHGwYBnk6zA6lUCLWrfGN6LRck5JVggbtLYbBmds/+zAsYXDxxT2I3j2aPz0jxPBS8Q1mOPSp5IG861bHyaGa94hoYEAKbb3NvHE9xo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=dn1DNepy; 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="dn1DNepy" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B5494C4CEE4; Thu, 17 Apr 2025 18:57:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1744916234; bh=Rf/PKusgWEe9f1n47I8d3vI/e4IorQVrj1aO3ii29Hg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=dn1DNepyJuC7b5M7PJG6Q3e7X797GkLdJuI2GMp8TVqR38Ub/BVqsoM/s6FMlOg4X /TaGoTsWo1zwcoEh6C6vbcvZBHs4ZmSjSXCKFVWwMUAI15jndeF6uSmMmWWggaebht ILqvJlPbW3aYgxd+T9bYwf6cFfEsiuQIvysVe7Vg= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Roberto Ricci , Myrrh Periwinkle , Ingo Molnar , "Rafael J. Wysocki" , Ard Biesheuvel , "H. Peter Anvin" , Kees Cook , Linus Torvalds , David Woodhouse , Len Brown Subject: [PATCH 6.12 388/393] x86/e820: Fix handling of subpage regions when calculating nosave ranges in e820__register_nosave_regions() Date: Thu, 17 Apr 2025 19:53:17 +0200 Message-ID: <20250417175123.213005409@linuxfoundation.org> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20250417175107.546547190@linuxfoundation.org> References: <20250417175107.546547190@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Myrrh Periwinkle commit f2f29da9f0d4367f6ff35e0d9d021257bb53e273 upstream. While debugging kexec/hibernation hangs and crashes, it turned out that the current implementation of e820__register_nosave_regions() suffers from multiple serious issues: - The end of last region is tracked by PFN, causing it to find holes that aren't there if two consecutive subpage regions are present - The nosave PFN ranges derived from holes are rounded out (instead of rounded in) which makes it inconsistent with how explicitly reserved regions are handled Fix this by: - Treating reserved regions as if they were holes, to ensure consistent handling (rounding out nosave PFN ranges is more correct as the kernel does not use partial pages) - Tracking the end of the last RAM region by address instead of pages to detect holes more precisely These bugs appear to have been introduced about ~18 years ago with the very first version of e820_mark_nosave_regions(), and its flawed assumptions were carried forward uninterrupted through various waves of rewrites and renames. [ mingo: Added Git archeology details, for kicks and giggles. ] Fixes: e8eff5ac294e ("[PATCH] Make swsusp avoid memory holes and reserved memory regions on x86_64") Reported-by: Roberto Ricci Tested-by: Roberto Ricci Signed-off-by: Myrrh Periwinkle Signed-off-by: Ingo Molnar Cc: Rafael J. Wysocki Cc: Ard Biesheuvel Cc: H. Peter Anvin Cc: Kees Cook Cc: Linus Torvalds Cc: David Woodhouse Cc: Len Brown Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20250406-fix-e820-nosave-v3-1-f3787bc1ee1d@qtmlabs.xyz Closes: https://lore.kernel.org/all/Z4WFjBVHpndct7br@desktop0a/ Signed-off-by: Myrrh Periwinkle Signed-off-by: Greg Kroah-Hartman --- arch/x86/kernel/e820.c | 17 ++++++++--------- 1 file changed, 8 insertions(+), 9 deletions(-) --- a/arch/x86/kernel/e820.c +++ b/arch/x86/kernel/e820.c @@ -754,22 +754,21 @@ void __init e820__memory_setup_extended( void __init e820__register_nosave_regions(unsigned long limit_pfn) { int i; - unsigned long pfn = 0; + u64 last_addr = 0; for (i = 0; i < e820_table->nr_entries; i++) { struct e820_entry *entry = &e820_table->entries[i]; - if (pfn < PFN_UP(entry->addr)) - register_nosave_region(pfn, PFN_UP(entry->addr)); - - pfn = PFN_DOWN(entry->addr + entry->size); - if (entry->type != E820_TYPE_RAM && entry->type != E820_TYPE_RESERVED_KERN) - register_nosave_region(PFN_UP(entry->addr), pfn); + continue; - if (pfn >= limit_pfn) - break; + if (last_addr < entry->addr) + register_nosave_region(PFN_DOWN(last_addr), PFN_UP(entry->addr)); + + last_addr = entry->addr + entry->size; } + + register_nosave_region(PFN_DOWN(last_addr), limit_pfn); } #ifdef CONFIG_ACPI