From nobody Mon Feb 9 04:45:35 2026 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (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 1D7C0217727; Mon, 7 Apr 2025 17:29:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744046982; cv=none; b=PWUEJD60kzDBSML1WkMrDRTa3AxzwRL1Z2tIaAQvp0YWBucqdqg55HrAIhvxZ6m7Vv5e/M6UX9gOTiM2dTVdloaR8qxa75s/pcvreXWvrVSFenPhPv7052OokuUcKWORAQpE+F78EhNA+tm9KqxB7g7PyGCpdcLUVNLMztgV5+Y= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744046982; c=relaxed/simple; bh=Ae7s0sZ4Zx6k346VjblLIi165drnn7cUExdqbW77Dos=; h=Date:From:To:Subject:Cc:In-Reply-To:References:MIME-Version: Message-ID:Content-Type; b=QjTR8ocFkbEhE+Ag/lCY9koiu6VChcS/Hy2CyKisxHkuC6yDkYtmdp/+br6DjpWs0xNNDZRvhByw4+YAK7JBJDujDmFuPeQidpYbElEBNkIr3IclCPT9CJz6JS2zGhugiWQZO/h5ya8MZO2aUM10isg7KWx9C9/uhkO5dtcnfjA= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=xOnqdr91; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=Sj50TaCR; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="xOnqdr91"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="Sj50TaCR" Date: Mon, 07 Apr 2025 17:29:33 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1744046977; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=yYJveTcpMfqH/k0+ktUtmw8ttCMVtye0N3XZidpAX3Y=; b=xOnqdr91qssa5q23OLcemwEDw6REShJwFYdyL0M2O2uGhO0RXZjbh6YhLuntwChcs7g9v+ m/sdD7Pt4hOZ/unsT8TNO31dBJ83y7J4Ep3SHqqklK3uDYO8GeMlhTKx87kuGs+F2jRFzf V1b2bL7192YjWR8avTy5NPytcpL/6Nx3RsCb6PH+7fh++gIdHMOwVTqjDEp61XnnivwhED cMcNnDEjTskSZv4YghI02y6HxoLTRet7nFfbJpg4yhV6iXMh7N8ewW7rAwjMICe4omGVgH 7XON9NPD5paezd7WRZKawKYkEKPfzVrCHz38s7fyrOoSy7HPRUmD7XbZVf90mA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1744046977; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=yYJveTcpMfqH/k0+ktUtmw8ttCMVtye0N3XZidpAX3Y=; b=Sj50TaCRC7qjymRx3tpsBP/xoryPB35N2+K5HAYsFaqel2CWWVXZNrsu4FCTkZd+21OhN2 hf8q/tDyCqv92vAw== From: "tip-bot2 for Myrrh Periwinkle" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: x86/urgent] x86/e820: Fix handling of subpage regions when calculating nosave ranges in e820__register_nosave_regions() Cc: Roberto Ricci , Myrrh Periwinkle , Ingo Molnar , "Rafael J. Wysocki" , Ard Biesheuvel , "H. Peter Anvin" , Kees Cook , Linus Torvalds , David Woodhouse , Len Brown , stable@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20250406-fix-e820-nosave-v3-1-f3787bc1ee1d@qtmlabs.xyz> References: <20250406-fix-e820-nosave-v3-1-f3787bc1ee1d@qtmlabs.xyz> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-ID: <174404697318.31282.6099676690393066740.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Precedence: bulk Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable The following commit has been merged into the x86/urgent branch of tip: Commit-ID: f2f29da9f0d4367f6ff35e0d9d021257bb53e273 Gitweb: https://git.kernel.org/tip/f2f29da9f0d4367f6ff35e0d9d021257b= b53e273 Author: Myrrh Periwinkle AuthorDate: Sun, 06 Apr 2025 11:45:22 +07:00 Committer: Ingo Molnar CommitterDate: Mon, 07 Apr 2025 19:20:08 +02:00 x86/e820: Fix handling of subpage regions when calculating nosave ranges in= e820__register_nosave_regions() 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 m= emory 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/ --- arch/x86/kernel/e820.c | 17 ++++++++--------- 1 file changed, 8 insertions(+), 9 deletions(-) diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c index 57120f0..9d8dd8d 100644 --- a/arch/x86/kernel/e820.c +++ b/arch/x86/kernel/e820.c @@ -753,22 +753,21 @@ void __init e820__memory_setup_extended(u64 phys_addr= , u32 data_len) void __init e820__register_nosave_regions(unsigned long limit_pfn) { int i; - unsigned long pfn =3D 0; + u64 last_addr =3D 0; =20 for (i =3D 0; i < e820_table->nr_entries; i++) { struct e820_entry *entry =3D &e820_table->entries[i]; =20 - if (pfn < PFN_UP(entry->addr)) - register_nosave_region(pfn, PFN_UP(entry->addr)); - - pfn =3D PFN_DOWN(entry->addr + entry->size); - if (entry->type !=3D E820_TYPE_RAM) - register_nosave_region(PFN_UP(entry->addr), pfn); + continue; =20 - if (pfn >=3D limit_pfn) - break; + if (last_addr < entry->addr) + register_nosave_region(PFN_DOWN(last_addr), PFN_UP(entry->addr)); + + last_addr =3D entry->addr + entry->size; } + + register_nosave_region(PFN_DOWN(last_addr), limit_pfn); } =20 #ifdef CONFIG_ACPI