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 D6001192B72 for ; Fri, 9 Aug 2024 09:51:44 +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=1723197104; cv=none; b=exkN4uAFQXGh0kBmARq7oPm4CeOij2QCGC3F7PqchMvq9vrGSpvYfjoINrkvfo15vk42Atx/pqP5aKSiS+tFMoKdD7ullN+jcnhIbAUBXPC85FiIMojdL/ASt6dNlC4sqzxQ5SwM6q6HX4IZFRo3r8EbnG7A7hgSM7TipITeGNk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723197104; c=relaxed/simple; bh=yoWTOMYJ7N0gPpdKFp05wGY7L6C18hAglWYv1Er11PM=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=l+enoSHhuj9ETZTED8gPaN9gA78GZeAOO1uAD7wgM6UGldIwPdHRmjpXhnbgUt0OVmNv0Q4rP6PivSBWzoKaSBf67hQj460dV1D/PjDRWu7Z0eo+cacNePAG4azFJsZq/zrsJ04Fnwq5ePYO685eBcStKJrNYKIxD/M3pdCH3OU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 Received: by smtp.kernel.org (Postfix) with ESMTPSA id B8185C4AF0D; Fri, 9 Aug 2024 09:51:41 +0000 (UTC) Date: Fri, 9 Aug 2024 10:51:39 +0100 From: Catalin Marinas To: Jinjie Ruan Cc: Baoquan He , vgoyal@redhat.com, dyoung@redhat.com, paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, chenjiahao16@huawei.com, akpm@linux-foundation.org, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, linux-arm-kernel@lists.infradead.org, Will Deacon Subject: Re: [PATCH -next] crash: Fix riscv64 crash memory reserve dead loop Message-ID: References: <20240802090105.3871929-1-ruanjinjie@huawei.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Thu, Aug 08, 2024 at 03:56:35PM +0800, Jinjie Ruan wrote: > On 2024/8/7 3:34, Catalin Marinas wrote: > > On Tue, Aug 06, 2024 at 08:10:30PM +0100, Catalin Marinas wrote: > >> On Fri, Aug 02, 2024 at 06:11:01PM +0800, Baoquan He wrote: > >>> And I don't like the idea crashkernel=,high failure will fallback to > >>> attempt in low area, so this looks good to me. > >> > >> Well, I kind of liked this behaviour. One can specify ,high as a > >> preference rather than forcing a range. The arm64 land has different > >> platforms with some constrained memory layouts. Such fallback works well > >> as a default command line option shipped with distros without having to > >> guess the SoC memory layout. > > > > I haven't tried but it's possible that this patch also breaks those > > arm64 platforms with all RAM above 4GB when CRASH_ADDR_LOW_MAX is > > memblock_end_of_DRAM(). Here all memory would be low and in the absence > > of no fallback, it fails to allocate. > > > > So, my strong preference would be to re-instate the current behaviour > > and work around the infinite loop in a different way. > > Hi, baoquan, What's your opinion? > > Only this patch should be re-instate or all the 3 dead loop fix patch? Only the riscv64 patch that that removes the ,high reservation fallback to ,low. From this series: https://lore.kernel.org/r/20240719095735.1912878-1-ruanjinjie@huawei.com/ the first two fixes look fine (x86_32). The third one (arm32), not sure why it's in the series called "crash: Fix x86_32 memory reserve dead loop bug". Does it fix a problem on arm32? Anyway, I'm not against it getting merged but I'm not maintaining arm32. If the first two patches could be merged for 6.11, I think the arm32 one is more of a 6.12 material (unless it does fix something). On the riscv64 patch removing the high->low fallback to avoid the infinite loop, I'd rather replace it with something similar to the x86_32 fix in the series above. I suggested something in the main if block but, looking at the x86_32 fix, for consistency, I think it would look better as something like: diff --git a/kernel/crash_reserve.c b/kernel/crash_reserve.c index d3b4cd12bdd1..64d44a52c011 100644 --- a/kernel/crash_reserve.c +++ b/kernel/crash_reserve.c @@ -423,7 +423,8 @@ void __init reserve_crashkernel_generic(char *cmdline, if (high && search_end == CRASH_ADDR_HIGH_MAX) { search_end = CRASH_ADDR_LOW_MAX; search_base = 0; - goto retry; + if (search_end != CRASH_ADDR_HIGH_MAX) + goto retry; } pr_warn("cannot allocate crashkernel (size:0x%llx)\n", crash_size); In summary, just replace the riscv64 fix with something along the lines of the diff above (or pick whatever you prefer that still keeps the fallback). Thanks. -- Catalin