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 9C48B29374C; Mon, 5 May 2025 22:18:33 +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=1746483513; cv=none; b=AdCTBTfeCN+I/RH4A3RYMlLoPUvWhmUiNuG7ZrnGF+/Zgdth7V7FBtGxHdzhKu7KavvyCkdzjxz1AhvuyCbyNtvPh8OxVWrHlTqhw9m7e0PpQhXmaK6ecp6+yT0j9Jq5OmHojC0gctD3FLNuGwTknhklN3CxLeAYndQpged19a4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746483513; c=relaxed/simple; bh=XgH3XKm1IAc32eD0g9jNld7LDdIY89FxHXmbpYkLaJU=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=ZCg4jjDCHjBYBZ0NZ+Oe8OfWwUg/LkTJgGL4UqD+bSd0BI52xBIS/JSUPijSYrYCLgao+lBxMi94qp9XS0lRzxJPjrBPbqBn8CT/jcH760YIUtzNw44kj59984rwXq2E3xIK/lSjPXC12rBEJPSICNPD91gJO7TVTRu0RsigzaI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=I30BnIpK; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="I30BnIpK" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0B061C4CEEE; Mon, 5 May 2025 22:18:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1746483513; bh=XgH3XKm1IAc32eD0g9jNld7LDdIY89FxHXmbpYkLaJU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=I30BnIpK8ZqIzT/YffNhvvDCoT5dJfuTrbdPrYqJ9aT0eVo6aR11oDlXLFMSKQ2Br g8APrRvlCKQMunYlNhRvGcmO5UnMrkbtTcLIuR5vtMeuo+jCh0xEv7mHNGcjUsBLdy +2VLhpcxqF0ykORy6Hj9tp1bDtbOdeSVrcIxBk74EN3Gd4f32L1QkHaCTUgrMhR1Na aecuWvKM7vD+Z9Nel7HGKYgXx4uwy+REsCN26eoq8n49gIS40IFdkgm42jFBlZ0+JG /E4xMjsfFGC2TbXeFGnYBi1k10vzHvQOoQo193UiAsWIHkcQVy0FJKfW3Kr3Wy+u/P N/eYbBdekN7GA== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Philip Redkin , Ingo Molnar , Dave Hansen , Rik van Riel , "H. Peter Anvin" , Sasha Levin , luto@kernel.org, peterz@infradead.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, x86@kernel.org Subject: [PATCH AUTOSEL 6.14 089/642] x86/mm: Check return value from memblock_phys_alloc_range() Date: Mon, 5 May 2025 18:05:05 -0400 Message-Id: <20250505221419.2672473-89-sashal@kernel.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250505221419.2672473-1-sashal@kernel.org> References: <20250505221419.2672473-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 6.14.5 Content-Transfer-Encoding: 8bit From: Philip Redkin [ Upstream commit 631ca8909fd5c62b9fda9edda93924311a78a9c4 ] At least with CONFIG_PHYSICAL_START=0x100000, if there is < 4 MiB of contiguous free memory available at this point, the kernel will crash and burn because memblock_phys_alloc_range() returns 0 on failure, which leads memblock_phys_free() to throw the first 4 MiB of physical memory to the wolves. At a minimum it should fail gracefully with a meaningful diagnostic, but in fact everything seems to work fine without the weird reserve allocation. Signed-off-by: Philip Redkin Signed-off-by: Ingo Molnar Cc: Dave Hansen Cc: Rik van Riel Cc: "H. Peter Anvin" Link: https://lore.kernel.org/r/94b3e98f-96a7-3560-1f76-349eb95ccf7f@rarity.fan Signed-off-by: Sasha Levin --- arch/x86/mm/init.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c index 62aa4d66a032d..bfa444a7dbb04 100644 --- a/arch/x86/mm/init.c +++ b/arch/x86/mm/init.c @@ -645,8 +645,13 @@ static void __init memory_map_top_down(unsigned long map_start, */ addr = memblock_phys_alloc_range(PMD_SIZE, PMD_SIZE, map_start, map_end); - memblock_phys_free(addr, PMD_SIZE); - real_end = addr + PMD_SIZE; + if (!addr) { + pr_warn("Failed to release memory for alloc_low_pages()"); + real_end = max(map_start, ALIGN_DOWN(map_end, PMD_SIZE)); + } else { + memblock_phys_free(addr, PMD_SIZE); + real_end = addr + PMD_SIZE; + } /* step_size need to be small so pgt_buf from BRK could cover it */ step_size = PMD_SIZE; -- 2.39.5