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 ACFAF2989AD; Mon, 5 May 2025 22:41:49 +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=1746484909; cv=none; b=DAnegFud5vOgx45ZtvLsmH2RDiadvnrEOefY/bIEa4pCOYqqptrwJ2ZdmFADb1mbiW21wdR16xJv8hMDAFn06sNX+nvRpxJ8QvJaUwflZggNMpFw8mfmR7x6D6X9rkv57oHgETd6EqSxvUmgE2Afgje9EE2MvXdhewJcalPYUoA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746484909; c=relaxed/simple; bh=bHyz8c5tpBcqMqkz5kIdDIq0oeqPCdzWTDQUhNkqZGE=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=tYPrd5BbvKwxqOTzlJq8IYEg6drgGM7mDmMokgDe7iZqNEIrqQwWrd5U1jQDeIyjHz3RIaJonZKKP/vHOdI8HA9f7WWgpBSuva2ylg72+TJpaF+bF9S6AcK/ORaLcPwomDY8V0j8mWyjbozDxC6BfuPNAYV7G50dIveFdckj9uY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=joXavFqo; 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="joXavFqo" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CD561C4CEEE; Mon, 5 May 2025 22:41:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1746484909; bh=bHyz8c5tpBcqMqkz5kIdDIq0oeqPCdzWTDQUhNkqZGE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=joXavFqo/hmo2bDXI4o7T09XGkPpf+mbqeIrfgwkh5VjgnTjfJeVQYKqGBUPAC0sm vAymu44zg5eUAARoFdPgw5jNGo/sTYvlJ8wAsDnGv6dhJZtZsuoPQGRhti8rpYCia7 FTmJkN8M226OqxJwwgJZsjvF88ufzhM0XcpFfRQx1nbp7HDifxCYQjHx+rnRGu1UdN IoR64k0N2tVP+N9LhmZdxf2cxoJ9U4LJT50nsJeMJ8D2lBsZcEfjnOpI/2oRyJQ8Vv LLbdcvQZQm6DKE8SB7Giq5IYVBRx+WBWlKRVzdbqBra+H5scuSywxnVdeZ8sZKqkUJ i1hGEl8zHTkeA== 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 6.12 069/486] x86/mm: Check return value from memblock_phys_alloc_range() Date: Mon, 5 May 2025 18:32:25 -0400 Message-Id: <20250505223922.2682012-69-sashal@kernel.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250505223922.2682012-1-sashal@kernel.org> References: <20250505223922.2682012-1-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 6.12.26 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 101725c149c42..9cbc1e6057d3c 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