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 BEBA51F461D for ; Mon, 25 Aug 2025 10:55:46 +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=1756119347; cv=none; b=AAiPK4M/QjMQITJ5wLbhk2SDH9daOPC5RWZDmQuIvw+6V4eTVNUSSxapEvzj7/McFqQzn5eiFtVLkkg728dBklCqDZzo+dOhCYtP7mBZW5lPkXjpx9wy5E5K1O0YGIe+zB+ulmXum3eHq3P11XjRaqDdK4sFKf8PfzS/Id3DK8w= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756119347; c=relaxed/simple; bh=7Eo++RSHk60jXhrBRV6DAWQrmxZrOjIBQJ88YUsXAzk=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=SMpquabwj/gNBvz5PplFolhV4Be/N3hFttDRR0rtLQPxrR5EcnOUT7sdQQjnwngtKzyRhEv0ezW+FgKsoFl54b1omvT4izbImvNPnE43Hr9BwH+Y4NRRA5HzuwEXHxpg6i949Mx7/VACq35P86p7RpQxGJvSZsvRVFebxxwg0GY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=OH4dziab; 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="OH4dziab" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 13E22C113D0; Mon, 25 Aug 2025 10:55:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1756119346; bh=7Eo++RSHk60jXhrBRV6DAWQrmxZrOjIBQJ88YUsXAzk=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=OH4dziab8ewgT4fEKyE+VyC3wpI2KXsmvXVPNsOjfPFPCZ2IT3bNvsdcInGitkyKc KSIKLew8SsCYuyelEeMvqEkarU/6kEl3OHHHkrgbBLb/FHLvxjR5BTyTS9i39gdv+4 d9gUiRJ5OHmavsw0f5OjzLR5QB8gi0hxwQ2mmDiG+lBiYp9cwLHSLVA0vU40xV68mO 0mL2MaN2cv6JRZiGwb5J1xVV/sWs0QYYiGs5FgYjxsB+pdbwcGZsXiNHwJc8kIs9WH +7MhTHO1ntgh79jrZN2+Zl5IF0g8MxPGd1TQJtQOfuHGpcTZbYsgGtvASuTBjLYpph i4pjfnqOAUKzA== Message-ID: Date: Mon, 25 Aug 2025 05:55:45 -0500 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] nios2: ensure that memblock.current_limit is set when setting pfn limits To: schuster.simon@siemens-energy.com Cc: linux-kernel@vger.kernel.org, Andreas Oetken References: <20250821-nios2-adjust-lowmem-bounds-v1-1-ea2dd8661ae5@siemens-energy.com> Content-Language: en-US From: Dinh Nguyen In-Reply-To: <20250821-nios2-adjust-lowmem-bounds-v1-1-ea2dd8661ae5@siemens-energy.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 8/21/25 05:37, Simon Schuster via B4 Relay wrote: > From: Simon Schuster > > On nios2, with CONFIG_FLATMEM set, the kernel relies on > memblock_get_current_limit() to determine the limits of mem_map, in > particular for max_low_pfn. > Unfortunately, memblock.current_limit is only default initialized to > MEMBLOCK_ALLOC_ANYWHERE at this point of the bootup, potentially leading > to situations where max_low_pfn can erroneously exceed the value of > max_pfn and, thus, the valid range of available DRAM. > > This can in turn cause kernel-level paging failures, e.g.: > > [ 76.900000] Unable to handle kernel paging request at virtual address 20303000 > [ 76.900000] ea = c0080890, ra = c000462c, cause = 14 > [ 76.900000] Kernel panic - not syncing: Oops > [ 76.900000] ---[ end Kernel panic - not syncing: Oops ]--- > > This patch fixes this by pre-calculating memblock.current_limit > based on the upper limits of the available memory ranges via > adjust_lowmem_bounds, a simplified version of the equivalent > implementation within the arm architecture. > > Signed-off-by: Simon Schuster > Signed-off-by: Andreas Oetken > --- > This patch was tested internally on 5.10.x stable for some time now and > applies and boots cleanly on next-20250815, as well. > --- > arch/nios2/kernel/setup.c | 15 +++++++++++++++ > 1 file changed, 15 insertions(+) > > diff --git a/arch/nios2/kernel/setup.c b/arch/nios2/kernel/setup.c > index 2a40150142c3..f43f01c4ab93 100644 > --- a/arch/nios2/kernel/setup.c > +++ b/arch/nios2/kernel/setup.c > @@ -142,6 +142,20 @@ static void __init find_limits(unsigned long *min, unsigned long *max_low, > *max_high = PFN_DOWN(memblock_end_of_DRAM()); > } > > +static void __init adjust_lowmem_bounds(void) > +{ > + phys_addr_t block_start, block_end; > + u64 i; > + phys_addr_t memblock_limit = 0; > + > + for_each_mem_range(i, &block_start, &block_end) { > + if (block_end > memblock_limit) > + memblock_limit = block_end; > + } > + > + memblock_set_current_limit(memblock_limit); > +} > + > void __init setup_arch(char **cmdline_p) > { > console_verbose(); > @@ -157,6 +171,7 @@ void __init setup_arch(char **cmdline_p) > /* Keep a copy of command line */ > *cmdline_p = boot_command_line; > > + adjust_lowmem_bounds(); > find_limits(&min_low_pfn, &max_low_pfn, &max_pfn); > > memblock_reserve(__pa_symbol(_stext), _end - _stext); > > --- > base-commit: 1357b2649c026b51353c84ddd32bc963e8999603 > change-id: 20250818-nios2-adjust-lowmem-bounds-5d2d98af0fa8 > > Best regards, Applied! Queued for v6.18. Thanks, Dinh