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 3D93B2DA0E1; Mon, 5 May 2025 22:57:57 +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=1746485878; cv=none; b=NS5aMBSanPI4uPrhkRTPUNZud+n+CVSPWyUlqfAmvY/YELr5lfpj7ePB5/Z4PiK6wWEwwQWj/zPDXZrTenrMk8OCs4TFOQEI/79RhUpXIcfGf0KvT9jlpqslU0ZbQptaoBMY4Vou44Q7jV9L6e4QM4XJuMkCLXnJmHvxePy3Ogc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746485878; c=relaxed/simple; bh=j+EfqvvBXY4PJGPy+vQBKg7QLVsn7odm62WHCyOitj4=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=Ob8J+HstUr/KqgohV+t3+mnWXQY+IgdeawoF/EYxXAtDwJ1K2hSRlPY+LqbcOKoIFFAKdcHgqMJlrfCuQUixIb2otrnb6bXQY4RqnbGFAef2m0ABh3k8rGdB7Q1dWeGirvHPT5WE9Dps2w6TktcvdCCRzfaZefvRl7may/D+kEI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=UNuX9KrT; 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="UNuX9KrT" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 976DCC4CEF1; Mon, 5 May 2025 22:57:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1746485877; bh=j+EfqvvBXY4PJGPy+vQBKg7QLVsn7odm62WHCyOitj4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=UNuX9KrTtfpLf+QFXqN5inONXHJyCOBk3NeLNq7pHj9GJS9T2k09F742Ryzm4L1W/ sgxXw6vOXlLgWSg+b7TWYGhWnuPJyfO/6Dmmh31xYTWlmFc0C2kXPKqKjHLzAJ3Fxw o0UUNPguVE6rLNdsfZL8W1KSxwVzvrsT3HPifzguIvgJhIuE82kY6FwKi25DxhbfW1 +PyCeJoBe9zSjgp4crp928Bg9wwACMfyO7BDgHQwbPJ2vogN1e4ZzZJVz/UJXZHc17 yPtgAbzM61iLLdKuuhqVVhUfpthB9FtccYu3adOdkUH8litmrz9lmD48YCD1WqXJH0 TzLnuiltN51GA== 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 6.6 041/294] x86/mm: Check return value from memblock_phys_alloc_range() Date: Mon, 5 May 2025 18:52:21 -0400 Message-Id: <20250505225634.2688578-41-sashal@kernel.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250505225634.2688578-1-sashal@kernel.org> References: <20250505225634.2688578-1-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 6.6.89 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 71d29dd7ad761..6cbb5974e4f9e 100644 --- a/arch/x86/mm/init.c +++ b/arch/x86/mm/init.c @@ -644,8 +644,13 @@ 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